Publisher: AIP   (Total: 27 journals)   [Sort alphabetically]

Showing 1 - 27 of 27 Journals sorted by number of followers
Physics Today     Hybrid Journal   (Followers: 78, SJR: 0.66, CiteScore: 1)
J. of Applied Physics     Hybrid Journal   (Followers: 69, SJR: 0.739, CiteScore: 2)
American J. of Physics     Full-text available via subscription   (Followers: 58, SJR: 0.456, CiteScore: 1)
Physics of Fluids     Hybrid Journal   (Followers: 46, SJR: 1.19, CiteScore: 3)
Applied Physics Letters     Hybrid Journal   (Followers: 44, SJR: 1.382, CiteScore: 3)
J. of Chemical Physics     Hybrid Journal   (Followers: 36, SJR: 1.252, CiteScore: 2)
J. of Mathematical Physics     Hybrid Journal   (Followers: 25, SJR: 0.644, CiteScore: 1)
Review of Scientific Instruments     Hybrid Journal   (Followers: 20, SJR: 0.585, CiteScore: 1)
J. of Laser Applications     Full-text available via subscription   (Followers: 14, SJR: 0.741, CiteScore: 2)
APL Materials     Open Access   (Followers: 12, SJR: 1.63, CiteScore: 4)
Applied Physics Reviews     Hybrid Journal   (Followers: 11, SJR: 4.156, CiteScore: 12)
Physics of Plasmas     Hybrid Journal   (Followers: 10, SJR: 0.576, CiteScore: 1)
J. of Renewable and Sustainable Energy     Hybrid Journal   (Followers: 10, SJR: 0.44, CiteScore: 1)
Acoustics Today     Hybrid Journal   (Followers: 9)
Biomicrofluidics     Open Access   (Followers: 7, SJR: 0.592, CiteScore: 2)
AIP Advances     Open Access   (Followers: 7, SJR: 0.472, CiteScore: 1)
Low Temperature Physics     Hybrid Journal   (Followers: 6, SJR: 0.264, CiteScore: 1)
Structural Dynamics     Open Access   (Followers: 6, SJR: 1.625, CiteScore: 4)
J. of Physical and Chemical Reference Data     Hybrid Journal   (Followers: 4, SJR: 1.046, CiteScore: 3)
Chaos : An Interdisciplinary J. of Nonlinear Science     Hybrid Journal   (Followers: 3, SJR: 0.716, CiteScore: 2)
AIP Conference Proceedings     Full-text available via subscription   (Followers: 2)
Biointerphases     Open Access   (Followers: 1, SJR: 0.558, CiteScore: 2)
Chinese J. of Chemical Physics     Hybrid Journal   (Followers: 1, SJR: 0.24, CiteScore: 1)
Surface Science Spectra     Hybrid Journal   (Followers: 1, SJR: 0.416, CiteScore: 1)
Scilight     Full-text available via subscription  
APL Bioengineering     Open Access  
APL Photonics     Open Access  
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AIP Conference Proceedings
Number of Followers: 2  
 
  Full-text available via subscription Subscription journal
ISSN (Print) 0094-243X - ISSN (Online) 1551-7616
Published by AIP Homepage  [27 journals]
  • Technoeconomic cost analysis of NREL concentrating solar power Gen3 liquid
           pathway

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      Authors: Chad Augustine, Devon Kesseli, Craig Turchi
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The National Renewable Energy Laboratory is leading the liquid (molten salt) power tower pathway for the U.S. Department of Energy's concentrating solar power Gen3 initiative. The Gen3 liquid pathway required updated designs to three major components: the tower and receiver, the thermal energy storage tanks, and the power cycle. We assume a 100 MWe net system output and used the System Advisor Model (SAM) to complete a technoeconomic cost analysis of the Gen3 liquid pathway design and estimate its levelized cost of electricity. This paper summarizes the methodology and results of that analysis.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T03:00:00Z
      DOI: 10.1063/5.0085836
       
  • Simulation, control, and verification of novel closed-chain kinematics

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      Authors: David A. Gross, Benjamin Pelletier, Thai Khong, Alexander Sonn, Derek Schulte, Steve Schell
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Generalized two-axis kinematics have been used to facilitate the rapid design iteration of heliostat hardware in place of the rapid derivation of bespoke equations of motion. Such an approach is incomplete for closed-chain systems and is augmented and verified here for Heliogen's novel cable-driven pitch-roll heliostat. The benefits of such a heliostat design are highlighted and a new field layout parameterization is proposed to take advantage of these opportunities.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T03:00:00Z
      DOI: 10.1063/5.0087180
       
  • Techno-economic evaluation of the performance of an innovative rotary disk
           receiver concept in a CSP power plant

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      Authors: Xabier Rández, Fritz Zaversky, David Astrain
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      This study evaluates the thermal performance of an innovative discs receiver and models its effect in a CSP plant. Energetic and economic results were compared with a foam receiver developed in the European project CAPTure. The study consists of two parts, on the one hand, it treats the simulation of a CFD model of the innovative disk receiver, from which the thermal efficiency versus air outlet temperature curve was obtained, necessary to feed the second part of the study. This thermal efficiency was compared with the performance of a foam receiver. On the other hand, system- level simulations of a CSP multi tower plant are performed in order to obtain the effect of this efficiency-air outlet temperature curve on the overall energetic and economic performance. The study compares the LCOE and the yearly generation of the plant with the innovative discs receiver with that of the foam receiver. Results show the potential in economic and energetic terms of the new receiver in comparison to conventional foam receivers.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T03:00:00Z
      DOI: 10.1063/5.0085715
       
  • Computationally fast analytical ray-tracer for central receiver systems

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      Authors: Pascal Richter, Florian Hövelmann
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      An accurate and computationally fast ray-tracer is the key part for the simulation and optimization of the optical irradiation of a heliostat field layout in a solar central receiver system. Within this work we present an analytical ray-tracer which is fast in runtime while obtaining highly accurate results. The runtime improvement is achieved by a faster integration method that does not require a discretization of the receiver. This allows for discretizing the heliostat surface into smaller cells each having a representative flux function to better account for a variety of optical errors. Our new ray-tracer is implemented on the same C++ platform as other existing ray-tracers, such that reasonable cross validation with direct run-time comparisons are possible. Within a case study we demonstrate that the new convolution method decreases the run-time by a factor of 20 compared to HFLCal, and a factor of three compared a bidirectional Monte-Carlo ray-tracer, while achieving a stable accuracy of 99.98 %.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:59Z
      DOI: 10.1063/5.0085714
       
  • Economic assessment of installed CSP plants as Carnot Batteries: Spanish
           grid market case study

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      Authors: José L. de la Quintana, Andrés Sebastián, Rubén Abbas
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      This study analyzes the possibility of implementing Carnot Batteries in existing concentrating solar power plants taking into account the temporal compatibility of both systems in the Spanish grid market. A techno-economic study has been carried out using the electricity prices hourly evolution over the last five years for the detection of recognizable patterns. This work leads to the conclusion that the operation of the system in Carnot Battery mode generates positive operating profit between the months when the lowest incidence of solar radiation is obtained in the Spanish latitude. Furthermore, it is concluded that the storage capacity of the current CSP plants in Spain coincides with an economic optimal sizing for their operation in Carnot Battery mode.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:59Z
      DOI: 10.1063/5.0085717
       
  • The selection of expansion joint material for high-temperature
           multi-layered thermal energy storage bins

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      Authors: Eldwin Djajadiwinata, Muhammad Sarfraz, Shaker Alaqel, Abdelrahman El-Leathy, Nader S. Saleh, Rageh S. Saeed, Abdulelah Alswaiyd, Hany Al-Ansary, Sheldon Jeter, Syed Danish, Zeyad Al-Suhaibani
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Utilizing an efficient and reliable thermal energy storage (TES) bin in a concentrated solar power (CSP) systems can help to overcome the variability in the thermal energy supply due to the bad weather condition or during the off-sun period. At King Saud University (KSU), Saudi Arabia, a multilayered-wall TES bin has been developed to be used in a solid particle central receiver system. In this system, the multilayered-wall TES bin can reach a very high temperature and experience a thermal cycle. Therefore, the thermal expansion and compression will be significant which can cause cracks on the walls of the TES. One of the important layers used to avoid such a failure is the expansion joint layer. This research work attempts to further investigate various expansion joint materials for the TES bin, additional to the one which has been used in the previous design. Compression tests were conducted to find the suitable expansion joint materials. There were six (6) materials tested, i.e., asphalt, fibre, ceramar, sponge rubber, cork, and wooden fiber. Initially, room temperature compression tests were done. The room temperature tests were done in two stages, i.e., the preliminary stage and the advanced stage. The preliminary stage was a short test without cycling to quickly screen the prospective materials. The advanced stage was done to further test the best materials concluded from the first stage test. This test was done with longer compression holding-time and with cycling. The most promising materials from the room temperature tests were, then, tested at a higher temperature to simulate the real condition under which they will be utilized. The go/no-go criteria were how far the material recovers to its original thickness (referred to as the recovery value) and how fast after the compression it recovers (referred to as the recovery speed). The results showed that, at room temperature, sponge rubber has the highest recovery value and speed. However, at a higher temperature, all the materials have relatively low recovery values with the wooden fiber outperforms the others.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:59Z
      DOI: 10.1063/5.0085835
       
  • An experimental investigation of heat losses during charging the thermal
           storage tank in a particle-based CSP system

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      Authors: Nader S. Saleh, Shaker Alaqel, Eldwin Djajadiwinata, Rageh S. Saeed, Abdulelah Alswaiyd, Hany Al-Ansary, Abdelrahman El-Leathy, Sheldon Jeter, Syed Danish, Zeyad Al-Suhaibani, Said Abdel-Khalik, Muhammad Sarfraz
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      This paper presents results of an exploratory study aimed to investigate heat loss during charging the thermal energy storage (TES) bin with hot solid particles. Tests were performed at the pilot particle-based power tower plant in King Saud University in Riyadh, Saudi Arabia. In this plant, a small TES bin is installed between the particle heating receiver and the particle-to-working-fluid heat exchanger. Two types of experiments, the on-sun test and the steady-state test, were conducted; in each experiment, two cases were considered, namely the empty bin and full bin. Results show that in the case of empty TES bin, the air, entrained as a result of particles falling, can cause a significant temperature drop in the particle side. Moreover, the use of several particle-feeding lines can promote the so-called chimney effect. In the case of full bin, the amount of entrained air was reduced significantly, thus the temperature drop in the particle side was shrunk greatly. However, results also show that the air occupying the empty region (due to the particle’s angle of repose) inside the full bin recorded lower temperature than that of particles which implies that the chimney effect is still present.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:59Z
      DOI: 10.1063/5.0085837
       
  • Selecting a self-sufficient solar system configuration for 24/7,
           year-round, per-demand power supply

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      Authors: Pinchas Doron, Jacob Karni, Alexander Slocum
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      A structured unbiased methodology is applied to identify an optimized 24/7, year-round solar power system, based on the lowest system Levelized Electricity Cost (LEC`) and meeting other fundamental system requirements. The process leads to selection of a hybrid SCR-PV system that includes thermal energy storage and fuel production. Directions for future R&D and upgrading the method are indicated.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:58Z
      DOI: 10.1063/5.0085719
       
  • Actively shaped focusing heliostat

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      Authors: Roger Angel, Ryker Eads, Nick Didato, Matt Rademacher, Nick Emerson, Christian Davila
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      We describe a technology that uses a computer-driven, active servo control to change the shape of a heliostat reflector, in order to keep an image of the solar disc focused on a fixed distant target. The heliostat reflector is made with glass mirrors bent and rigidly attached to a support frame to form an initial specific concave toroidal shape. The different toroidal shapes needed throughout the day to maintain focus, despite the changing angle of the sun, are obtained by bending the frame by means of a truss of stiffening struts behind it. The struts are connected in pairs to a central back structural node, which incorporates linear actuators to change the truss geometry.For a hexagonal reflector, a total of three linear actuators suffice to adjust the amplitudes of the three lowest order orthogonal bending modes of the frame, and thereby to obtain all the different toroidal shapes needed for accurate imaging through the day. A recently constructed 1.6 m2 hexagonal prototype with three actuators has demonstrated this concept by producing sharp solar images throughout the day at a 40 m distant target. The measured flux concentration ranges from 90% to 98% into a square target measuring only 1.44 times the ideal disc diameter.Active heliostats of this type open new possibilities for nighttime solar electricity generation and solar industrial process heat, allowing fields of even relatively small numbers of heliostats to generate higher than current concentrations, as needed for high temperatures and more efficient energy conversion. A design for a scaled up hexagonal heliostat with 48 m2 reflector surface with eight petal mirror segments has been optimized using ANSYS. A 440 m diameter field of 776 of these heliostats would yield 25 MWth at 1,500x concentration by area, averaged over a cylindrical central receiver 2.75 m in height and diameter.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:58Z
      DOI: 10.1063/5.0086409
       
  • Shadowing and blocking factors in heliostats: Comparison between parallel
           and oblique projections

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      Authors: Toufik Arrif, Alberto Sánchez-González, Badreddine Bezza, Abdelfetah Belaid
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      This work reports two projection methods for the calculation of shadowing and blocking in the surrounding heliostat field of a Solar Tower Plant. The first one is the classical parallel projection which is widely used in the literature. The second one is the oblique projection which has been barely addressed in the literature. For the same solar altitude, the frames of two adjacent heliostats are not parallel in reality, and consequently, the projection of the shadowing and blocking areas is not parallel. Compared with raytracing methods, these two projection methods have been developed to reduce the computational cost without affecting efficiency accuracy. Therefore, they are suitable for heliostat field optimization. We have chosen a case study presented by Collado1, that used parallel projection in the calculations. Differences between parallel and oblique approaches are shown. Shading and blocking factors by the more accurate oblique projection are compared with the parallel one. The maximum difference is 0.09% and 1.44%, respectively for parallel and oblique projection in calculating the shading and blocking factor of a circular field of 4550 heliostats.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:58Z
      DOI: 10.1063/5.0085716
       
  • A novel high-efficiency solar thermal power plant featuring electricity
           storage - Ideal for the future power grid with high shares of renewables

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      Authors: Fritz Zaversky, Francisco Cabello, Ana Bernardos, Marcelino Sánchez
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      This paper proposes an innovative hybrid CSP – Compressed Air Energy Storage (CAES) combined cycle power plant configuration that provides very competitive electricity storage technology with long lifetime, which is highly competitive with respect to battery electric storage (BES). The concept initiates a new era of adaptive renewable power plants for optimum power grid management, enabling higher shares of renewables. Due to the fact that cheap off-peak electricity is used to provide the air compression work of the topping Brayton cycle, the overall peak solar-to-electric energy conversion efficiency of the proposed power plant may reach 40%, which roughly doubles the peak efficiency with respect to state-of-the-art CSP technology.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:57Z
      DOI: 10.1063/5.0085718
       
  • Evaluation of solar reference cells on a two-axis tracker using spectral
           measurements

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      Authors: Frank Yignola, Josh Peterson, Rich Kessler, Sean Snider, Afshin Andreas, Aron Habte, Peter Gotseff, Manajit Sengupta, Fotis Mavromatakis
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      A simple model calculating the performance of an IMT solar reference cell is proposed and tested under clear sky periods. One-minute data from EKO spectroradiometers collocated with an IMT reference cell are used for the analysis. Data are obtained at the NREL Solar Radiation Research Laboratory in Golden, Colorado and the UO Solar Radiation Monitoring Laboratory in Eugene, Oregon. The model is also applied and evaluated under cloudy conditions. A match of better than 1% is found between calculated clear sky values and IMT measurements for July, 2020. One- minute cloudy sky comparisons show a much larger variation, but when averaged over one hour, a standard deviation of 4% between the calculated and measured values is found.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:57Z
      DOI: 10.1063/5.0085841
       
  • 100-Gigawatt-hour crushed-rock heat storage for CSP and nuclear

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      Authors: Charles Forsberg, Ali S. Aljefri
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      We are developing 100-GWh heat-storage systems for use with Concentrated Solar Power (CSP) and nuclear reactor systems. Crushed rock fills a container up to 20 m high and 250 m by 250 m with insulated floor, walls and roof structures. Heat is transferred from the heat source to the crushed rock and then to the power cycle using (1) heat transfer oils for lower-temperature power systems to 400°C or (2) nitrate salts for higher-temperature power systems to 600°C. In charging mode, hot heat transfer fluid is sprayed over crushed rock and drains through the rock to the collection pans at the bottom to be reheated. Sections of rock are heated sequentially. In discharge mode cold heat transfer fluid is sprayed over crushed rock and drains through the rock to the collection pan below to deliver hot fluid to the power cycle. This design minimizes the inventory and thus the cost of heat transfer oil or liquid nitrate salt. The large container size minimizes the surface to volume ratio and thus insulation and structural costs. Crushed rock is the lowest-cost storage material. The goal is to drive storage capital costs down to several dollars per KWh of heat.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:57Z
      DOI: 10.1063/5.0085684
       
  • Ray tracing approach for the performance evaluation of bladed and
           flat-plate receiver in central tower systems

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      Authors: Sanjoy Chatterjee, Narayanan Venkatakrishnan
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Optical field design on the ground and the design of receiver system are two challenging tasks in the field of concentrated solar thermal technologies (CSTT). Ray tracing techniques have routinely been used to estimate the power reaching receiver in a given heliostat field. Although the conventional flat receiver has been extensively investigated in terms of efficiency, bladed receiver configurations offer improved efficiency due to better light-trapping ability enabling the flux on individual blades to be increased without exceeding the maximum (peak) limitation. We investigate an optical model of flat receiver and compare its efficiency with a bladed receiver using commercially available ray tracing software. Higher ray tracing efficiency was observed in bladed receiver configuration compared to flat receiver. Additionally, the receiver closest to the ground in bladed receiver configuration shows highest efficiency.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:56Z
      DOI: 10.1063/5.0086896
       
  • Development of a modular concrete heliostat prototype

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      Authors: Patrick Forman, Sebastian Penkert, Andreas Pfahl, Jürgen Schnell, Peter Mark
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The main idea of this contribution is to replace typical steel structures for heliostats by means of concrete due to its low costs. With respect to accuracy demands, a high-performance concrete is used that possesses high compressive and tensile strengths. The collector is designed as a strut-like structure with main radial beams and a central mount to ensure high stiffness. The design exhibits a circular shape to reduce shading. For construction, the concrete collector is dissolved into equal modules derived from symmetry reduction methods enabling a serial production. To show the feasibility, a small-scale prototype with a diameter of 3.2 m and a mirror area of 8 m² is developed that will be built up and qualified at the solar power tower Jülich, Germany. It consists of 4 modules and exhibits a weight of 341 kg.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:56Z
      DOI: 10.1063/5.0086016
       
  • Design of a novel compact single-source high-flux solar simulator

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      Authors: Angus Boswell, Lane Hunter-Leiski, Charles Wetaski, Muhammad Taha Manzoor, Melanie Tetreault-Friend
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      We present the design and development of a novel compact single-source high-flux solar simulator. The simulator will be used to study properties of fluids subjected to radiation-induced natural convection and volumetric heating, and for design optimization of volumetric solar thermal receivers. The simulator incorporates a pre-assembled light source unit with a custom frame made from common off-the-shelf components. The light source unit comprises a 6.5kWe Xenon-Mercury arc lamp coupled with a truncated ellipsoid rear reflector, while the frame is constructed from aluminum extrusions for simple integration of additional optical elements. The novel simulator design features a moveable light source suspended directly above the target plane. The simulator configuration allows for experimental set-ups not possible with traditional configurations, including sensitive or high-temperature experiments during which the sample cannot be manipulated, and experiments which require a variable beam diameter. The footprint of the simulator is 5’ by 5’, allowing the system to integrate into small lab spaces. Finally, a light-attenuating curtain was designed and characterized using a ray tracing model. Key curtain parameters were established, and the influence of the curtain on the flux distribution was characterized.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:55Z
      DOI: 10.1063/5.0085840
       
  • Development and testing of a solar flux heating freeze recovery system for
           molten salt parabolic troughs

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      Authors: Luca Imponenti, Juan Carlos Herruzo, Ryan Shininger, Hank Price, Juan Valverde
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      A major obstacle preventing commercialization of molten salt parabolic trough plants is freeze protection and recovery of the solar field. One of the most common nitrate salt compositions under consideration allows for solar field outlet temperatures up to 565°C and begins solidifying above 240°C. Using molten salt directly in the solar field can significantly reduce thermal energy storage costs and the higher temperature compared to oil heat transfer fluids can power a more efficient power cycle, but the very high freezing point is cause for concern. This work builds on a previous modeling effort investigating different methods for melting Solar Salt frozen in the solar field, which suggested the viability of a novel solar heating method to lower costs of the freeze protection system. In this work higher fidelity models are developed to better investigate the melting process with a more detailed 3D geometry which includes the insulated bellows. The thermal-fluid model of the melting process is updated to include temperature dependent density and data for solid phase properties. In addition, a finite element model is developed to resolve thermal stresses at the point with highest thermal gradients. Results with the new model confirm the viability of using controllable solar flux heating to thaw salt frozen in the solar field without damaging the receiver; however, the presence of non-illuminated sections significantly slows down the melting process. Solar heating simulations with pauses off-sun of 120 and 60 s require 18.5 and 11.9 h to melt salt from a night-time temperature of 10°C with 1000 W m2 DNI, which results in maximum thermal stresses of 48.2 and 53.5 MPa, respectively. Adding 150 W m−1 to the solar heating simulation with a 60 s pause off-sun decreases both the melt time and thermal stresses due to the more uniform heating, suggesting a combined heating method may be the best option.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:55Z
      DOI: 10.1063/5.0087108
       
  • Large HelioPod™ field layout design and optimisation

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      Authors: Tristan Mckechnie, Craig McGregor, Gerhard Venter
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      In this paper a new methodology is developed for the design of optimised HelioPod™ field layouts. The methodology is inspired by pattern based optimization techniques and aims to replicate the benefits of the radial stagger layout for pod fields. The newly developed methodology is compared to an existing heuristic design method and shown to outperform this method.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:55Z
      DOI: 10.1063/5.0085721
       
  • Concentrating solar technology for generation of high temperature
           industrial process heat in South Africa: A pre-feasibility study in
           sustainable hydrogen production

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      Authors: Seranya Moodley, Jaap Hoffmann
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Sustainable methods of hydrogen production are directly dependent on the price of electricity used in driving the water splitting process. There is a limit to the cost reduction that can be achieved by increasing the efficiency of the electrolyser and it is evident to reduce the levelized cost of hydrogen significantly below the limit of the electricity price influence, the introduction of heat into the process is required. This both reduces the electric consumption of the water splitting process as well as allows for the introduction of a cheaper source of energy into the system. Integration with renewable energy sources to meet the thermal and electric demand has the potential to reduce the cost of production of hydrogen. In South Africa, concentrating solar thermal (CST) technology has the potential to provide high quality and quantity process heat required to meet the thermal demand of thermo-chemical water-splitting processes due to a favorable solar resource. CST technology also presents advantages such as increasing the capacity factor of the plant through thermal energy storage, and minimizing plant thermal cycling and variable input loads. Pre-feasibility assessment of the technology suitability to large-scale central hydrogen production, technology maturity rate to allow establishment of the industry within global carbon reduction goals in 2050 and economic viability of equipment lifespan and material suitability to meet central hydrogen production cost target of 2 $/kg was found unfavourable in the current study. A levelized cost of hydrogen through thermochemical water splitting with central receiver solar thermal technology providing both heat and electric energy requirements was found to be 10.49 $/kg with a cycle efficiency of 22.87%. Grid supplied electricity and process heat with central receiver solar thermal technology was found to be 9.56 $/kg with a cycle efficiency of 30.91%.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:55Z
      DOI: 10.1063/5.0085722
       
  • Hydrogen mitigation process testing at Nevada solar one

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      Authors: Greg C. Glatzmaier, Koenraad F. Beckers
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The National Renewable Energy Laboratory (NREL) and Acciona Solar Power (ASP) developed and installed a process that addresses the issue of hydrogen buildup in Acciona’s Nevada Solar One power plant. Our method selectively removes hydrogen from the expansion tanks of the power plant to control hydrogen levels in the circulating heat-transfer fluid (HTF). During previous work, we developed a sensor that measures hydrogen partial pressure in the expansion-tank headspace gas. We demonstrated that our sensor measures hydrogen levels over a wide range of partial pressure from 10 mbar down to 0.003 mbar. More recently, we conceived and developed an integrated process module that performs both hydrogen sensing and separating functions. The sensor/separator measures hydrogen partial pressure in the headspace gas in the same way as our original sensor design. Additionally, the integrated module separates hydrogen from the headspace gas to reduce hydrogen to the level needed to maintain the performance of receivers in the collector field. Laboratory testing at NREL showed that the sensor function had an accuracy of ±7%, and the hydrogen extraction rate for separator function was consistent with our modeling predictions. The primary benefit of this module is its simple design, both in terms of function and incorporation into the HTF subsystem of the power plant. Most recently, NREL and ASP completed installation and initial testing of a mitigation process at ASP’s Nevada Solar One power plant in Boulder City, Nevada. In this paper, we report on the completed installation, initial testing, and plans to bring the process to full automation, so that it can be operated unattended on a daily schedule.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:54Z
      DOI: 10.1063/5.0086416
       
  • Irradiance maps from a shadow camera on a mountain range

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      Authors: Stefan Wilbert, Bijan Nouri, Norbert Kötter-Orthaus, Natalie Hanrieder, Christoph Prahl, Pascal Kuhn, Luis Zarzalejo, Roberto Lázaro
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Spatially and temporally highly resolved direct normal irradiance (DNI) maps of the solar field can be used to significantly improve the operation of concentrating solar power (CSP) plants. Further improvements are expected if DNI nowcasts are also used for the plant operation. Currently, the most widely used method to create spatially resolved DNI nowcasts is based on all sky imagers. All sky imagers take photos of the whole sky above the CSP plant and detect clouds to derive the DNI map. Such all sky imager systems are promising, but for the calculation of DNI maps the cloud height and shape must be determined. Depending on the conditions, these processing steps can be error prone. Shadow cameras avoid these complex tasks. Mounted on an elevated position, they take photos of the ground in which cloud shadows can be detected. The RGB values of the photos and one measurement station in the camera's field of view are used to derive the DNI for each pixel of the photo. So far, a shadow camera system was mounted on a solar tower, covering an area of about 4 km². However, mirror surfaces and ground shaded by structures seen in the images cannot be evaluated with the method. Together with the low spatial extension, this so far excluded the shadow camera approach from the application in utility scale CSP plants. To overcome these limitations, a shadow camera is mounted on a mountain range. The evaluation method is adapted to the large distances between the camera and the ground and the results are compared to ground based DNI measurements. Considering that a simple surveillance camera is used the results are satisfying. The method is promising for tower plants and other solar power plants located close to mountain ranges or high buildings and can also help to provide highly resolved forecasts of global irradiance for areas with distributed solar energy systems.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:54Z
      DOI: 10.1063/5.0085723
       
  • Next-generation concentrating solar power plants: Perspectives on
           international markets

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      Authors: Cara Libby, William Gould
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Decade-long growth in concentrating solar power (CSP) deployment has resulted in over 6,000 MW of operational capacity today. In the past several years, the first utility-scale central receiver CSP systems entered commercial operation, including many with integrated thermal energy storage (TES) capability. Next-generation central receiver systems are targeting operating temperatures above 700°C and use of a closed Brayton power cycle with supercritical CO2 (sCO2) as the working fluid. These systems intend to deliver greater value through improved operating efficiency, dramatic cost reductions, and improved ability to provide grid benefits. EPRI examined international perspectives and preferences surrounding the future role, market, and technical capabilities for CSP. CSP experts from five countries with roles in utility resource planning, government energy policy and regulation, and solar project development participated in in-depth interviews that explored country-specific market needs and desired technology attributes and capabilities that would ensure market relevancy. Topics spanned current and future needs for baseload, intermediate, and peaking power; barriers and incentives for CSP; and support for next-generation central receiver (Gen3 CSP) technologies, among others. Additional insights and examples from the US and other countries are included where appropriate.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:53Z
      DOI: 10.1063/5.0087100
       
  • Development of a 500 °C semi-pilot scale supercritical CO2 power
           cycle test loop

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      Authors: Bongsu Choi, Junhyun Cho, Jongjae Cho, Hyungki Shin, Chulwoo Roh, Beomjoon Lee, Gilbong Lee, Ho-Sang Ra, Gyunchul Hur, Eunseok Wang, Young-Jin Baik
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The supercritical carbon dioxide (sCO2) power cycle has been researched in various fields such as concentrated solar power (CSP), fossil fuel power, and nuclear power due to its high thermal efficiency, compact size, and low levelized cost of electricity (LCOE). In particular, in the case of CSP, while the sCO2 cycle has been studied as an alternative to the steam Rankine cycle, it remains at a low technology readiness level. At the Korea Institute of Energy Research (KIER), researchers have been studied the sCO2 system to demonstrate its operability since 2013. The 500°C semi-pilot scale test loop is the fifth cycle and is a dual recuperated cycle. The target is to run the cycle continuously for 2 h at 500°C and 130 bar while generating over 50 kWe. The main components include a high-temperature turbine A, low-temperature turbine B, compressor, flue gas heater, two recuperators, and a cooler. All these components were fabricated, and the full test loop construction was completed. Prior to the commissioning, turbine B which is an axial impulse-type turbo-generator, was preliminarily tested and a power of 12.6 kWe was successfully generated. In the compressor test, CO2 of 3.72 kg/s was pressurized to 96 bar at 70,000 rpm. For the heater, a pilot burner and main burner were ignited, and CO2 was heated to 140°C using flue gas at 350°C.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:53Z
      DOI: 10.1063/5.0085681
       
  • Enhanced production of C2-hydrocarbons and hydrogen from catalytic methane
           decomposition in a tubular reactor heated by concentrated solar energy

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      Authors: Hiroyuki Kimura, Stéphane Abanades, Satoshi Seo
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      This study focuses on the solar thermo-catalytic methane decomposition for hydrogen and C2-hydrocarbons production in an indirectly-irradiated tubular solar reactor. The proposed concept is based on a two-step process encompassing the CH4 decomposition into C2-hydrocarbons and hydrogen at high temperatures, followed by the decomposition of C2-hydrocarbons into solid carbon and hydrogen at lower temperatures (both steps can be catalyzed using metal catalysts). Methane decomposition represents an attractive approach for CO2-free hydrogen production using concentrated solar energy as the high-temperature process heat source. A series of solar experiments were conducted to investigate the effect of the addition of gas quenching operation at the downstream of the heating section in the reactor for the production of C2-hydrocarbons and hydrogen from methane at high-temperature (1,400 °C). The results showed a slight improvement of C2H2 yield in the case without catalyst but CH4 conversion and H2 yield decreased significantly in this case. Conversely, a significant improvement of C2H2 yield was observed when adding catalyst (W strips) without reducing the CH4 conversion.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:53Z
      DOI: 10.1063/5.0086250
       
  • Matrix and control design of fixed-bed regenerators for a multi-tower
           decoupled advanced solar combined cycle

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      Authors: Saioa Herrero López, Susana López Pérez, Jonathon McGuire
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      A fixed-bed regenerative heat exchanger has been developed as a system for enabling the thermohydraulic connection to be made between a volumetric solar receiver (non-pressurized air circuit) and a Brayton turbine (a pressurized air circuit) in the context of the CAPTure project. The design of the ceramic beds is addressed in terms of selecting ceramic block geometries and matrix sizing. The control strategy for the regenerative system is also developed, thus establishing the proper sequence for connection changes to enable the turbine to operate continuously. Both designs are approached and verified via simulation, for which detailed, dynamic bed and complete system models are developed.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:52Z
      DOI: 10.1063/5.0086373
       
  • Oil testing for intense use in CSP applications

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      Authors: Emiliana Mansi, Salvatore Sau, Irena Balog, Alessia Cemmi, Marco Ciotti, Natale Corsaro, Giampaolo Caputo, Francesco Filippi, Fabio Panza, Nicolò Ratto, Andrea Simonetti, Annarita Spadoni, Giuliano Tiranti, Anna Chiara Tizzoni, Maria Cristina Annesini
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The aim of this work is to characterize an aromatic thermal oil against its maximum working temperatures with a preliminary laboratory scale oil stability characterization, to study the oil behavior under thermal stress. At this purpose, a dedicated laboratory scale set-up was built-up to undergo an oil sample to thermal stress tests. A mixture of C13-C20 alkyl substitute benzene was chosen as a representative aromatic oil to be studied.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:52Z
      DOI: 10.1063/5.0086253
       
  • Numerical heat transfer modelling of a centrifugal solar particle receiver

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      Authors: Serdar Hicdurmaz, Evan F. Johnson, Johannes Grobbel, Lars Amsbeck, Reiner Buck, Bernhard Hoffschmidt
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Solar particle receivers promise higher operating temperatures compared to molten salt-based receivers. The Discrete Element Method (DEM) tool LIGGGHTS is used to simulate the particle motion in a centrifugal solar particle receiver. A separate thermal model is developed in MATLAB, which uses the particle positions calculated with the DEM simulation. Heat transfer at the particle scale is accounted for with models of particle-particle conduction, particle-fluid- particle conduction, and a newly developed short-range radiation model. Radiation between large internal surfaces of the receiver are modeled with a view factor based long-range radiation model, and concentrated incident radiation is modeled with the Monte Carlo method. A thermal simulation for a lab-scale receiver is run for a relevant set of operational parameters, with key results being the temperature distribution and thermal efficiency of the receiver.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:52Z
      DOI: 10.1063/5.0086375
       
  • Modeling the thermal behavior of solar salt in electrical resistance
           heaters for the application in PV-CSP hybrid power plants

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      Authors: Zahra Mahdi, Phani Srujan Merige, Ricardo Alexander Chico Caminos, Pascal Schmitz, Ulf Herrmann, Cristiano Teixeira Boura, Mark Schmitz, Hans Gielen, Yibekal Gedle, Jürgen Dersch
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Concentrated Solar Power (CSP) systems are able to store energy cost-effectively in their integrated thermal energy storage (TES). By intelligently combining Photovoltaics (PV) systems with CSP, a further cost reduction of solar power plants is expected, as well as an increase in dispatchability and flexibility of power generation. PV-powered Resistance Heaters (RH) can be deployed to raise the temperature of the molten salt hot storage from 385 °C up to 565 °C in a Parabolic Trough Collector (PTC) plant. To avoid freezing and decomposition of molten salt, the temperature distribution in the electrical resistance heater is investigated in the present study. For this purpose, a RH has been modeled and CFD simulations have been performed. The simulation results show that the hottest regions occur on the electric rod surface behind the last baffle. A technical optimization was performed by adjusting three parameters: Shell-baffle clearance, electric rod-baffle clearance and number of baffles. After the technical optimization was carried out, the temperature difference between the maximum temperature and the average outlet temperature of the salt is within the acceptable limits, thus critical salt decomposition has been avoided. Additionally, the CFD simulations results were analyzed and compared with results obtained with a one-dimensional model in Modelica.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:51Z
      DOI: 10.1063/5.0086268
       
  • Next-CSP concept with particle receiver applied to a 150 MWe solar tower

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      Authors: Frédéric Siros, Benoît Valentin, Bo Liu, Jan Baeyens, Gilles Flamant
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The current benchmark for CSP is the molten salt tower. The next generation of CSP plant should keep the general architecture of the current benchmark – namely the molten salt tower with its direct storage – but should operate at higher temperatures in order to downsize its solar field through higher efficiency. Solid particles are the best candidate today to replace the molten salt as storage medium. They are used as both storage medium and heat transfer fluid that works as an in-tube upward bubbling fluidized bed in the solar receiver.Next-CSP is a project funded by the European Union’s H2020 program that aims at developing a new concept of particle solar receiver and validating it with a 1.2 MWe demonstration plant. The project also includes the study of a future utility-scale plant based on the concept in order to assess its technical and economic feasibility. This paper outlines the preliminary design of such a 150 MWe Next-CSP plant. Cost estimates were made with reasonable uncertainties to make design choices but are not dealt with in this paper.The plant is designed as a peaker that generates power during the evening. Due to inherent limitations of the concept, the solar receiver is a cavity one with a limited thermal output, which makes a multi-tower configuration mandatory. Our plant has six towers, each one with one receiver. Bucket elevators were chosen to lift the particles from ground level to the receivers. The layout of the whole solar island was optimized to minimize the cumulated length of the network that horizontally conveys the particles between the storage system and the six towers. The chosen layout, named “Vertical Star”, allows for a cumulated length of 4.0 km, which is still very challenging in terms of Capex and thermal losses. Continuous-flow conveyors and proper design limit the thermal losses to 5%.The power cycle is an externally-heated gas turbine operated in combined cycle. Whilst the bottoming steam cycle is standard, the gas turbine features a double reheat in order to achieve a combined cycle efficiency approaching 50%. The heat exchangers that provide the heat from the particles to the gas turbine are numerous (ten) and bulky.To conclude, the deployment of a utility-scale Next-CSP plant can realistically be envisioned; however, some technical challenges must be dealt with carefully, especially the thermal losses of the solar receiver and the particle conveying network.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:51Z
      DOI: 10.1063/5.0086301
       
  • Initial validation of an advanced heliostat characterization system based
           on cameras and light detectors

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      Authors: Adrián Peña-Lapuente, Íñigo Les, Amaia Mutuberria, Marcelino Sánchez, Carlos Heras, Íñigo Salinas, Marina Sevilla, David Izquierdo
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The design of the commercial Solar Power Tower Plants erected during the last years has been strongly influenced by the need of increasing the output power of the receiver to reach cost-effective plants. This trend has led to large heliostat fields with a vast number of long-distance heliostats that cannot be accurately characterized by the state- of-the-art methodology. Besides, the trend in heliostat design during the last decade has been the reduction of the heliostat size. This reduces, in the same way, the flux density produced by each heliostat individually, which makes it even harder to characterize the heliostat in a precise way. In order to surpass the state-of-the-art capabilities, a novel technique and an advanced measuring system was developed to characterize heliostat reflected beams. This system can accurately measure the power density distribution of any heliostat independently of its size or distance by its direct measurement using an array of opto-electronic detectors with a novel scanner-based procedure, in which the reflected beam drifts over the system due to the Sun movement while the heliostat remains immobile. In this context, this article presents the development status of the prototype built to demonstrate all the capacities that this innovative technique has. In addition, the results obtained during the initial tests performed as a proof of concept of the technique are presented, which shows really promising results in terms of measurement quality and potential to succeed in reaching high-quality characterization for both distant and small heliostats. Moreover, the development of a novel capability for the presented technique is presented, which provides the ability to characterize the heliostat surface slope by using a set of cameras attached to the characterization system and taking advantage of its scanning procedure.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:51Z
      DOI: 10.1063/5.0085728
       
  • Lessons learned designing a 50MW baseload CSP, PV, BESS, and gas hybrid

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      Authors: Brian Menzies, Luke Hardiman
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      This paper presents the initial findings from production modelling of a hybrid renewable energy plant situated in Mount Isa, Qld Australia. This opportunity required the plant to provide reliable baseload generation within a highly constrained mini-grid setting, and at a cost lower than that projected for gas generated electricity in the region. Oversizing the PV and the addition of a BESS allowed the PV to provide baseload power during the day while the inclusion of a modular CSP plant with 14.5 hours TES allowed for dispatchable solar energy to be utilised to generate through the night. The final configuration of the plant resulted in 83% of the energy being sourced from renewable technologies while successfully meeting reliability requirements at a cost that is competitive for the region.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:50Z
      DOI: 10.1063/5.0089017
       
  • Practical challenges to calibrate a heliostat with a multi-copter

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      Authors: Schalk J. Lombard, Willie J. Smit
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Heliostat calibration is very time-consuming. It takes several months to calibrate the heliostat-field in a concentrated solar power (CSP) and thermal (CST) plant. Since a particular heliostat cannot be calibrated often, it has to keep its calibration accuracy for several months. Therefore, heliostats are manufactured to be very robust and sturdy, which makes the installation costly. A possible solution to the issue of calibration time is to change the calibration technique. The proposed calibration technique makes use of a multi-copter to calibrate the heliostat. In theory, a multi-copter can calibrate more than one heliostat at a time and have more calibration time per day than the current conventional method of calibration. This would results in a significant decrease in the duration of the calibration process.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:50Z
      DOI: 10.1063/5.0085695
       
  • How can deep learning be used to improve the heliostat field calibration,
           even with small data sets' - A transfer learning comparison study

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      Authors: Max Pargmann, Daniel Maldonado Quinto
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      A precise and reliable alignment of the two-axis heliostat tracking is of great importance for an efficient operation of solar power towers. In order to minimize the tracking error of heliostats, especially in large plants, it is essential to recalibrate the heliostat control unit regularly. Conventional calibration methods with regression can meet the requirements of frequent and regular use, but they cannot adequately account for the many factors that influence alignment. Deep learning algorithms have made remarkable progress in recent years and have the potential to reduce the number of calibrations over time while reducing tracking errors. However, neural networks are still rarely used for such purposes, because such algorithms usually require an extremely large amount of data to map the individual heliostat errors. We present a comparison of different pre-train studies for neural networks to reduce the amount of data per heliostat which are needed to improve the accuracy compared to a state-of-the-art method by applying supervised as well as unsupervised pretraining.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:50Z
      DOI: 10.1063/5.0085731
       
  • Holistic optimisation of modular field design including heliostats,
           receivers, towers, HTF piping and operations

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      Authors: Bruce Leslie, Kurt Drewes
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      This paper examines the optimisation of a modular tower field CSP plant enabled by the use of sodium as the heat transfer fluid (HTF). It considers how the optimisation differs from a central tower field optimisation. The paper assesses the effect of the number of modular fields, field size, field aspect ratio, HTF piping optimisation, heliostat design, solar array optimisation, receiver sizing, and cleaning constraints on the whole plant operational and cost efficiency. The iterative techno-economic study has demonstrated the importance of allowing multiple aspects of component design, solar array morphology, manufacturing technique and material, manufacturing and installation cost, and efficient operations to interact fully, and the ways in which these interactions can result in accepted optimisation wisdoms being contradicted.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:50Z
      DOI: 10.1063/5.0089018
       
  • Solar optical performance of SiC receiver tubes

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      Authors: Kristen Frey, Eric Barringer, Nathan Schroeder, Clifford K. Ho
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      As part of a DOE Small Business Innovative Research (SBIR) project, CTP explored options to enhance the solar optical properties of its solar receiver tube. Sandia National Laboratories (Sandia) working with CTP, performed high-flux solar simulator tests on several receiver-tube specimens. The results demonstrated the excellent durability and optical performance of SiOC composite receiver tubes at 800°C surface temperatures.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:49Z
      DOI: 10.1063/5.0086424
       
  • Technical assessment of Brayton cycle heat pumps for the integration in
           hybrid PV-CSP power plants

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      Authors: Zahra Mahdi, Jürgen Dersch, Pascal Schmitz, Simon Dieckmann, Ricardo Alexander Chico Caminos, Cristiano Teixeira Boura, Ulf Herrmann, Christian Schwager, Mark Schmitz, Hans Gielen, Yibekal Gedle, Rauno Büscher
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The hybridization of Concentrated Solar Power (CSP) and Photovoltaics (PV) systems is a promising approach to reduce costs of solar power plants, while increasing dispatchability and flexibility of power generation. High temperature heat pumps (HT HP) can be utilized to boost the salt temperature in the thermal energy storage (TES) of a Parabolic Trough Collector (PTC) system from 385 °C up to 565 °C. A PV field can supply the power for the HT HP, thus effectively storing the PV power as thermal energy. Besides cost-efficiently storing energy from the PV field, the power block efficiency of the overall system is improved due to the higher steam parameters. This paper presents a technical assessment of Brayton cycle heat pumps to be integrated in hybrid PV-CSP power plants. As a first step, a theoretical analysis was carried out to find the most suitable working fluid. The analysis included the fluids Air, Argon (Ar), Nitrogen (N2) and Carbon dioxide (CO2). N2 has been chosen as the optimal working fluid for the system. After the selection of the ideal working medium, different concepts for the arrangement of a HT HP in a PV-CSP hybrid power plant were developed and simulated in EBSILON®Professional. The concepts were evaluated technically by comparing the number of components required, pressure losses and coefficient of performance (COP).
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:49Z
      DOI: 10.1063/5.0086269
       
  • Estimating orientations of tracking heliostats using circumsolar radiance

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      Authors: Alexander Sonn, Harel Dor, Jian Ma, Tori Cook, Steve Schell, Christian Gregory
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Accurately tracking heliostats typically requires obtaining and using feedback to improve the aim. It is possible to obtain this feedback while tracking a heliostat to the receiver by using measurements of the circumsolar radiance reflected near the receiver to estimate the mirror orientation. It is beneficial to map the radiance of the circumsolar region and incorporate these maps when estimating mirror orientations. We present an implementation of such a system and discuss our results.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:49Z
      DOI: 10.1063/5.0087117
       
  • Proposal and sizing of a molten Salt-to-sCO2 heat exchanger in
           supercritical solar thermal power plants

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      Authors: María José Montes, José Ignacio Linares, Rubén Abbas, Alexis Cantizano, Rubén Barbero, José Porras
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Solar Thermal Power Plants (STPPs), based on supercritical CO2 (sCO2) cycles, seem to be a promising alternative to increase the global solar-to-electric efficiency. The most conventional scheme for this technology is a molten salt (MS) central receiver, working at high temperature (above 700°C), coupled to the sCO2 cycle. For this scheme it is proposed a new design of the source heat exchanger that transfers the thermal energy from the molten salt to the CO2: the Compact Honeycomb Heat Exchanger (CHHE), in which the molten salt goes through a larger circular duct that is surrounded by 6 smaller trapezoidal ducts, through which the sCO2 circulates. This paper is focused in the thermal model of this new heat exchanger, and a thermo- economic optimization for a selected supercritical STPP.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:49Z
      DOI: 10.1063/5.0085730
       
  • System-level comparison of sodium and salt systems in support of the Gen3
           liquids pathway

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      Authors: Armando Fontalvo, Salvatore Guccione, Ye Wang, Shuang Wang, Zebedee Kee, Charles-Alexis Asselineau, Daniel Potter, Felix Venn, Janna Martinek, Craig Turchi, Joe Coventry, John Pye
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      This paper presents the comparison of the annual performance and the Levelised Cost of Energy (LCOE) of two high- temperature solar power tower configurations using a 565MWth chloride salt receiver and a 540 MWth liquid sodium receiver. Each power tower consists of a sodium or salt receiver, a 175 m high concrete tower, and a two-tank chloride salt system for thermal energy storage (TES). The power plants were simulated using SolarTherm to estimate their energy per year, capacity factor, and LCOE. The simulation was verified against the System Advisor Model (SAM), showing that the LCOE calculation differences are within ±1.0%. Results showed that the sodium-receiver system yields 69.60 USD/MWh real LCOE, versus 78.55 USD/MWh for the chloride salt system. Results also showed that sodium wins here due to a smaller and more efficient receiver, enabled by higher flux limits and reduced field size, leading to less mirror reflective area and site improvement cost.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:48Z
      DOI: 10.1063/5.0087911
       
  • Numerical performance evaluation of the Synhelion absorbing gas solar
           receiver under different operating conditions

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      Authors: Simone A. Zavattoni, Davide Montorfano, Philipp Good, Gianluca Ambrosetti, Maurizio C. Barbato
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The thermochemical process of syngas production, exploiting concentrated solar power, requires thermal energy at very high temperature, in the order of 1000-1500 °C, well beyond the maximum operating temperature of actual commercial receivers. The absorbing gas solar receiver, proposed by Synhelion SA, represents a breakthrough in the point focus solar technology allowing to operate at temperature levels higher than 1500 °C. This innovative cavity-type receiver exploits thermal radiation, as major heat transfer mechanism, for directly heating the gaseous heat transfer fluid (water vapor or carbon dioxide). Given the complexity of the physical phenomena taking place into the receiver, a CFD-based approach was followed to accurately replicate its thermo-fluid dynamics behavior under different operating conditions. In detail, a total of three CFD simulations campaigns, assuming the receiver operating at ambient pressure or at 10 bars, were performed with the aim of evaluating the effect of important parameters, such as heat transfer fluid entrance angle, gravity and realistic concentrated solar flux distribution into the cavity, on the receiver performance. An incoming concentrated solar flux on the aperture of 1.2 MW/m2 (corresponding to 600 kW/m2 on the absorptive surfaces) was assumed as reference leading to a total input power of 120 MW and 240 kW in the case of unpressurized and pressurized receiver respectively. According to the results obtained, gravity resulted to be the parameter with major influence followed by realistic concentrated solar flux distribution and heat transfer fluid entrance angle. However, a minimum receiver thermal efficiency of 66%, at about 1600 °C outflow temperature, was observed under the worst operating conditions considered indicating the reliability and robustness of this innovative receiver deign.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:48Z
      DOI: 10.1063/5.0085733
       
  • Conversion of boehmite to higher alumina phases by direct irradiation with
           concentrated light: Numerical modelling and experimental verification

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      Authors: Konstantinos E. Kakosimos, Navaira Fathima, Ma’moun Al-Rawashdeh
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Solar energy conversion to chemicals and fuels receives progressively more attention. Many of the possible conversion routes incorporate particles or could be transformed into particle-phase reactions, with one of these promising routes being aerosol reactors directly illuminated with concentrating light. Directly irradiated particles in aerosol phase can combine the advantages of fast heat and mass transfer rates with higher optical efficiencies compared to indirect solar reactors. Therefore, this study utilized mathematical models and qualitative experiments to demonstrate the potential of such reactors and processes using the conversion of aluminum hydroxide particles (Boehmite or gibbsite) to higher Alumina phases. In particular, the numerical simulations showed the prospect of fine tuning a concentrated light driven aerosol (particle) process to achieve higher selectivity of specific products by taking advantage of the very high heat transfer rates and details of the reaction mechanism. This was also verified with complementary experiments of an immobilized bed of particles exposed to short duration concentrated light pulse.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:48Z
      DOI: 10.1063/5.0085732
       
  • Inductive projection planning: Putting CSP in the picture

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      Authors: Javier Bonilla, Luis Crespo
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The progressive contribution of renewables is key to decarbonize electricity systems. However, high shares of intermittent renewables remain a worldwide concern. Least Cost Capacity Expansion models are heavily led by short- sighted cost criteria and they do not take into account the feedback on the hourly electricity markets influencing investments. Their outcomes are often unrealistic and cannot come true with the current market rules, as they would require huge hidden subsidies because the captured price by non-dispatchable renewables would be often below the market price. Inductive approaches – based on actual hourly production from renewables and assigning the expected cost trends to each one of the technologies – would yield more realistic, actionable solutions. The aim of this paper is to present a planning approach for the new installed capacity, Inductive Projection Planning (IPP), an advanced tool that optimizes with respect to multiple objectives, has been developed using the Spanish case as an example. The necessity of CSP for a true energy transition in shown, avoiding excessive fossil-fueled backup generation.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:47Z
      DOI: 10.1063/5.0085735
       
  • Exergy analysis of the impact of a heat exchanger on performance of an
           integrated sodium-salt CSP plant

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      Authors: Meige Zheng, Salvatore Guccione, Armando Fontalvo, Joe Coventry, John Pye
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      High-temperature receivers are critical for third-generation (Gen3) Concentrating Solar Power (CSP) technology to achieve high system efficiencies, and play the role of converting concentrated sunlight into heat. In this paper, two CSP systems with different working fluids in the receiver are examined in order to achieve identical supply of heat to the power block: a direct high-temperature chloride salt system and an indirect high-temperature sodium receiver with an associated heat exchanger to heat the same chloride salt. The presented numerical model indicates that the indirect sodium-salt system has a 4.37% higher exergy efficiency than the direct chloride salt system. The exergy destruction in the added sodium-salt heat exchanger was only 0.54%, which did not outweigh the performance benefits gained from using a sodium receiver, when compared to the direct salt case with no heat exchanger. Even at lower DNIs, the better heat-transfer characteristics of the sodium are responsible for its improved performance compared to salt in the receivers.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:47Z
      DOI: 10.1063/5.0087912
       
  • Dynamic simulation of a 50MW solar power tower system for peak load
           regulation

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      Authors: Qiang Zhang, Kaijun Jiang, Xiaoze Du, Ershu Xu, Lijun Yang
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      In spite of the discontinuous nature of solar energy, concentrated solar power (CSP) plant with thermal energy can not only stabilize output but also be operated as a peak load regulation plant in a multi-energy system. This work demonstrates the dynamic characteristics of the key heat transfer components and thermal transport processes of a solar power tower (SPT) plant with thermal energy storage, which is operated under the disturbances of external environment and electricity demand. A 50MW commercial power tower plant is chosen as the study object. Detailed systematic dynamic models based on two modelling method of essential sub-systems are developed, implemented, and integrated into TRNSYS to improve the reliability of simulation as well as the prevision accuracy. The model is completed with a control strategy that regulates the water level in the evaporator efficiently. System-level simulation is conducted by two time scales, during a couple of minutes, and on a couple of hours. It is shown that the model can provide theoretical reference data for the unit operating characteristic analysis, predict the trend of the plant thermal characteristics. The thermal transport characteristics in the steam generation system and steam turbine have been revealed, which is useful for the study of regulatory mechanisms for a peak-shaving plant.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:47Z
      DOI: 10.1063/5.0085853
       
  • Development of a micro heliostat and optical qualification assessment with
           a 3D laser scanning method

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      Authors: Ricardo Alexander Chico Caminos, Pascal Schmitz, Vikrama Atti, Zahra Mahdi, Cristiano Teixeira Boura, Johannes Christoph Sattler, Ulf Herrmann, Patrick Hilger, Simon Dieckmann
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The Solar-Institut Jülich (SIJ) and the companies Hilger GmbH and Heliokon GmbH from Germany have developed a small-scale cost-effective heliostat, called “micro heliostat”. Micro heliostats can be deployed in small-scale concentrated solar power (CSP) plants to concentrate the sun's radiation for electricity generation, space or domestic water heating or industrial process heat. In contrast to conventional heliostats, the special feature of a micro heliostat is that it consists of dozens of parallel-moving, interconnected, rotatable mirror facets. The mirror facets array is fixed inside a box-shaped module and is protected from weathering and wind forces by a transparent glass cover. The choice of the building materials for the box, tracking mechanism and mirrors is largely dependent on the selected production process and the intended application of the micro heliostat. Special attention was paid to the material of the tracking mechanism as this has a direct influence on the accuracy of the micro heliostat. The choice of materials for the mirror support structure and the tracking mechanism is made in favor of plastic molded parts. A qualification assessment method has been developed by the SIJ in which a 3D laser scanner is used in combination with a coordinate measuring machine (CMM). For the validation of this assessment method, a single mirror facet was scanned and the slope deviation was computed.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:47Z
      DOI: 10.1063/5.0086262
       
  • Innovative 1000K sodium loop for qualification of new materials for
           applications in CSP field

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      Authors: Alexandru Onea, Wolfgang Hering, Sven Ulrich, Michael Rieth, Alfons Weisenburger, Jens Reiser, Stephan Lenk, Thomas Röbert, Steffen Vielhaber, Siegfried Baumgärtner, Rainer Ziegler, Robert Stieglitz
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The present paper describes the 1000K sodium loop developed at the Karlsruhe Institute of Technology for creep fatigue and corrosion/erosion investigations of new materials for applications in the concentrating solar power plants. The construction of the high temperature loops is motivated also by the lack of experimental data for steels in flowing sodium at temperatures above ∼650°C, as revealed by the literature review. The study discusses the loop operation procedures and the safety measures considered. Some of the experimental results obtained so far are presented, namely the loop operations at maximal specified temperature, at maximal specified flow rate, the calibration of the sodium flowmeter and the dynamic flow conditions in the loop. The new materials proposed at KIT for the receiver are briefly presented.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:46Z
      DOI: 10.1063/5.0087110
       
  • Harvesting optimal operation strategies from historical data for solar
           thermal power plants using reinforcement learning

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      Authors: Zhichen Zeng, Dong Ni
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Operation strategy optimization for concentrating solar power (CSP) plants has been a long-studied topic in solar energy. In our work, an effective and systematic approach has been developed to harvest optimal operation strategies for CSP plants via reinforcement learning (RL). Our goal is to find the optimal strategy, which instructs the operation of different key operating variables of CSP plants in order to maximize daily power generation under a given solar irradiation series. Key variables are extracted through data mining techniques, and Deep Q-Network (DQN) is applied to find the optimal solution to the problem. A case study based on a 10MW central tower receiver solar thermal plant’s operating data is carried out, which shows great improvement in power generation through our proposed method.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:46Z
      DOI: 10.1063/5.0085691
       
  • Supercritical CO2 heat pumps and power cycles for concentrating solar
           power

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      Authors: Joshua D. McTigue, Pau Farres-Antunez, Ty Neises, Alexander White
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Pumped Thermal Energy Storage (PTES) is a promising technology for electricity storage applications. An electrically driven heat pump moves energy from a cold space to a hot space, thereby creating hot and cold thermal storage. The temperature difference between the hot and cold storage is later used to drive a heat engine and return electricity to the grid. In this article, supercritical carbon dioxide (sCO2) is chosen as the working fluid for PTES, and results are compared to ‘conventional’ systems that use nitrogen. Molten salts are used for the hot storage which means that a CSP plant with thermal storage and an sCO2 power cycle could potentially be hybridized with PTES by the addition of a heat pump. This article describes some of the benefits of this combined system which can provide renewable power generation and energy management services. Two methods by which an sCO2 heat pump can be combined with an sCO2 power cycle for CSP are described and techno-economic results are presented. Results indicate that these systems can achieve reasonable technical performance, but that costs are currently high.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:45Z
      DOI: 10.1063/5.0090002
       
  • Deriving in-field light transmittance in a tower CSP plant

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      Authors: Eyal Freud, Morag Am-Shallem, Rotem Hayut
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      A considerable fraction of the solar energy that “fuels” a tower CSP plant is lost between the heliostats and the receiver due to scattering and absorption by atmospheric gases and aerosols. Measuring this effect in the field is challenging, but quantifying it is important in the planning phase of the plant as well as during operations and performance assessment. BrightSource have developed the DAST system to derive the transmittance of the solar energy in real time and operates it at the 121 MW Ashalim tower CSP plant in Israel. The system consists of an integrating nephelometer and an aerosol monitor and it accounts for additional physical factors to convert the raw measurements to transmittance data. The DAST system is portable and modular, it can run online or offline, it operates in all weather conditions – day or night and it requires very little maintenance. The uncertainty in the derived transmittance values is typically below ∼2%, and they are in-line with the measurements of a long path transmissometer.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:44Z
      DOI: 10.1063/5.0086191
       
  • Modeling thermal transients of bulk particle lifting systems with CFD
           simulations

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      Authors: Matthew Cleal, Clifford K. Ho
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Computational Fluid Dynamics modeling of two different high-temperature particle lifting systems was done in order to be able to capture the thermal behavior of these systems. The two lifting mechanism modeled were a closed bucket elevator that carries the particles up a shaft with a conveyor belt of buckets, and a skip hoist that goes through a cycle of loading, lifting, unloading, and lowering. Both of the modeled systems were subject to a validation process, where the bucket elevator was compared to IR images taken of a real bucket elevator in use under high temperature conditions, and the skip hoist was compared to a 1-D MATLAB model using the heat equation. Both models showed reasonable validation results, and therefore an insulation thickness study was done on both models in order to show the capability of using Computational Fluid Dynamics tools for analysis on these types of systems as a way to inform design decisions. The results were able to show the relationship between increased insulation and lower particle temperature loss of the systems and was able to do so for both steady state and transient results.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:44Z
      DOI: 10.1063/5.0086070
       
  • Receiver design and On-Sun testing for G3P3-USA

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      Authors: Clifford K. Ho, Nathaniel R. Schroeder, Hendrik F. Laubscher, Lindsey Yue, Brantley Mills, Reid Shaeffer, Joshua M. Christian, Kevin J. Albrecht
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      This paper summarizes the evolution of the Gen 3 Particle Pilot Plant (G3P3) receiver design with the goal of reducing heat losses and increasing thermal efficiencies. New features that were investigated included aperture covers and shrouds, active airflow, multistage catch-and-release devices (stairs), and optimization of receiver cavity geometry. Simulations and ground-based testing showed that a reduced receiver volume and aperture shroud could reduce advective heat losses by ∼40 – 50%, and stairs could increase opacity and reduce backwall temperatures. The reduced volume receiver and stairs were selected for on-sun testing, and receiver efficiencies up to 80 – 90% were achieved in the current test campaign. The receiver thermal efficiency generally increased as a function of incident power and particle mass flow rates. In addition, particle outlet temperatures were maintained to within ±10 °C of a prescribed setpoint temperature up to ∼700 °C using a PID controller that adjusted the particle mass flow rate into the receiver in response to the measured particle outlet temperatures.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:44Z
      DOI: 10.1063/5.0086071
       
  • The development of a modular level cost model and its application in
           conceptual design particle lift system for a commercial scale solid
           particle concentrated solar power plant

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      Authors: Kenzo Repole, Sheldon Jeter
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      This paper outlines the development and application of a novel modular-based cost model which can be used in heavy industry cost. The flexibility of application examined where key characteristics of components are used to determine the component cost. The cost model is applied to the critical component particle transport system of a commercial scale solid particle concentrated solar power tower.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:43Z
      DOI: 10.1063/5.0085936
       
  • The modeling and simulation of an elevated temperature particle lift used
           in a commercial-scale solid particle concentrated solar power plant

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      Authors: Kenzo Repole, Sheldon Jeter
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      This paper outlines the development of the modeling and simulation of an elevated temperature particle lift intended to transport solid particles from the lower temperature storage bin to the top of the commercial-scale solid particle concentrated solar power tower. Traditional industry spreadsheet modeling is used as a starting point for the development of a complex non-linear design optimization model and a physics-based dynamic model that has the ability to simulate failures and analyze the particle response to such failures.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:43Z
      DOI: 10.1063/5.0085937
       
  • The transient thermal model for the application of an elevated temperature
           particle lift bucket elevator system in an experimental solid particle
           concentrated solar power plant

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      Authors: Kenzo Repole, Sheldon Jeter, Joshua Christian
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      This paper outlines the development of a transient thermal model of a critical component bucket elevator for use in transporting elevated temperature solid particulates to the top of a solid particle concentrated solar power tower. The lumped thermal capacitance approach is used. The model is used to analyze and optimize the internal and external insulation and to determine the sensitivity of the different design parameters to the overall design.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:43Z
      DOI: 10.1063/5.0085938
       
  • Transient thermal modeling for the optimization of an elevated temperature
           particle lift hoist system in a solid particle concentrated solar power
           plant

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      Authors: Kenzo Repole, Sheldon Jeter
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      This paper outlines the development of a preliminary a thermal transient lump capacitance model for a hoist based solid particle lift for a CSP tower. The CSP tower is a conceptual commercial-scale CSP, and the LCM analyzes the temperature and heat loss of the skip components during an 8-hour operating period and a subsequent 16-hour downtime. This LCM model is preliminary but has the ability to include more HSL components in the future. The conceptual CSP design is a preliminary design used for the development of this simulation and not a finalized design.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:43Z
      DOI: 10.1063/5.0085939
       
  • Narrow-channel fluidized beds for particle-sCO2 heat exchangers in next
           generation CPS plants

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      Authors: Jesse R. Fosheim, Xavier Hernandez, Jeremy Abraham, Azariah Thompson, Bradley Jesteadt, Gregory S. Jackson
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Transferring heat into and out of inert oxide particles in cost-effective, volumetrically efficient heat exchangers remains a principal challenge to implementing particle-based thermal energy storage (TES) in concentrating solar power (CSP) plants with efficient high-temperature supercritical-CO2 (sCO2) Brayton cycles. Engineered alumina-silica particles offer a robust storage media for temperatures well above 700°C. To date, primary particle-sCO2 heat exchangers rely on moving packed beds, which require large surface areas and volumes of expensive Ni-based alloys due to low overall heat transfer coefficients typically less than 300 W m-2 K−1. The limiting thermal resistance at the particle-wall interface can be reduced greatly with bubbling fluidization such that the overall heat transfer coefficients increase above 600 W m−2 K−1. Bubbling fluidized beds of net-downward flowing particles in narrow channels provides an effective method of adopting moving packed bed plate designs while greatly reducing the required surface area and thereby the size and costs of particle-sCO2 heat exchangers. The present work explores experimentally in a 0.25 x 0.10 x 0.018 m narrow-channel fluidized bed the influence of operating conditions on particle-wall heat transfer. Heat transfer measurements with alumina-silica particles (CARBOBEAD CP 40/100 with Sauter mean diameter of 260 µm) demonstrate that low superficial gas velocities as low as 125% of the minimum fluidization velocity greatly enhance particle-wall heat transfer while maintaining bed solid volume fractions above 40%. Particle-wall heat transfer increases with bed temperature due to increases in gas thermal conductivity and increased radiative exchange at higher temperatures. In agreement with past studies, a shallow peak in particle-wall heat transfer occurs at intermediate gas velocities due to the tradeoff of greater particle mixing and reduced solid volume fraction with increasing gas velocities. A new correlation for particle-wall heat transfer coefficients fitted to the test data provides a basis for identifying operating conditions for particle-sCO2 heat exchangers to achieve particle-wall heat transfer coefficients above 1000 W m−2 K−1 and overall heat transfer coefficients above 700 W m−2 K−1 with gas-to-particle mass flow ratios below 2%. The high heat transfer coefficients in narrow-channel fluidized beds can enable smaller, cost-effective particle heat exchangers for full-scale particle-based TES in next-generation CSP plants.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:43Z
      DOI: 10.1063/5.0085934
       
  • Using DNI forecasts provided by all sky imager to improve control of
           parabolic trough solar fields

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      Authors: Tim Kotzab, Tobias Hirsch, Bijan Nouri, Zeyad Yasser, Daniel Angulo Duque
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The solar field of a parabolic trough power plant is a complex thermal and hydraulic system. It is used to bring the heat transfer fluid (HTF) up to the desired temperature. The mass flow for the entire solar field is usually controlled from the plant control room. In the ideal case, the controller will adjust the mass flow so that the desired temperature is reached and all collector in the solar field are in full focus. Under transient conditions like a cloud passing through, different temperatures of the HTF can occur in the solar field. For example, the area not covered by a cloud can become hotter whereas temperatures in the area with cloud cover drop. In case the mass flow is adapted to the average irradiance level in the field, this scenario can lead to significant defocusing of those collector rows seeing high DNI but suffering from reduced mass flow. State of the art solar field controllers can use information on current DNI derived from one or a few pyrheliometers distributed over the solar field. Information on DNI distribution or an appropriate average DNI are thus not available. Recent developments in all sky imager (ASI) systems provide such spatially resolved DNI information and open the way for new control approaches. In this study, an irradiance forecasting system is used based on all sky imagers (ASI) to provide spatially resolved DNI maps of the whole solar field. With the ASI system, the controller can access information about the spatial DNI distribution and thus has knowledge about individual clouds in the solar field. In this paper, a model based approach to improve the feed forward control of the mass flow is investigated The detailed model used by the controller represents the current state of the solar field using most recent sensor data from the real solar field. With the forecasts of the ASI system as input, several simulations are performed to determine a suitable mass flow for the upcoming minutes. Under cloudy conditions, the new system shows advantages compared to a reference controller using only the DNI information from the elapsed time step. The investigation are carried out with ideal forecast and forecasts including uncertainties. For a test set of 27 days, the new control concept is able to reduce the number of emergency defocusing events by 9% under ideal forecasts and 5.7% when considering uncertainties. The average focus state of the field is increased by about 0,25%.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:42Z
      DOI: 10.1063/5.0086235
       
  • Development progress of the CentRec® particle receiver technology

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      Authors: Matti Lubkoll, Miriam Ebert, Lars Amsbeck, Alexander Hirt, Cathy Frantz, Jens Rheinländer, Reiner Buck
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The centrifugal particle receiver technology (CentRec®) is predicted to contribute significantly to reduction in levelized cost of electricity I heat (LCOE I LCOH) for concentrating solar power (CSP) and concentrating solar thermal (CST) applications. Main drivers are derived from the benefit offered from solid particles as heat transfer medium (HTM) and storage medium which are reduced receiver cost, increased operating temperature range and lower cost for the HTF itself. Previously, the CentRec® receiver was tested at the Solar Tower Ji.lich under significant part load due to optical restrictions of the facility. The results confirmed the expectation into receiver performance and motivated further projects to improve systems understanding as well as full load operational experience. This paper provides an overview over the currently ongoing projects aimed at improving the understanding of the CentRec® receiver through operation in a lab- environment at the DLR’s Synlight facility and a test campaign at the National Solar Thermal Test Facility (NSTTF) of the Sandia National Laboratories. Initial results from a study of increasing the receiver size are shown. Lastly, two new commercial scale CentRec® installations are introduced. These include a full test loop at the DLR’s new Multi Focus Tower in Ji.lich, Germany, and a complete plant being developed and built as a technology demonstrator in Foggia, Italy.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:42Z
      DOI: 10.1063/5.0086510
       
  • Manufacturing cost analysis of advanced parabolic trough collector

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      Authors: Parthiv Kurup, Stephen Glynn, Sertaç Akar
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The research team performed a detailed bottom-up manufacturing cost estimate for an advanced parabolic trough design — the Solar Dynamics Sunbeam-MT (Sunbeam Mid-Term). This includes all components for manufacturing and assembly in a manufacturing facility (e.g. space frame and arms), and the purchased parts (e.g. mirrors and receiver tubes). Estimates of the construction and assembly activities have been made to then determine an estimated installed cost. Prior analysis has already undertaken detailed bottom-up manufacturing, assembly, and construction analysis for the Ultimate Trough from schlaich bergermann partner (sbp), and this work updates the solar field cost estimates based on a similar aperture area as the SunBeam-MT. For this analysis, the Ultimate Trough is considered the commercial parabolic trough and the Sunbeam-MT as the advanced parabolic trough. For similarity, both the Sunbeam-MT and the Ultimate Trough have been modelled with a solar field with approximately 800,000 square meters (m2) in aperture area —the equivalent of a large CSP plant. The analysis has found a potential installed cost estimate of the Sunbeam-MT could be $120/m2 but must be built at scale to confirm this estimate. Compared to prior analysis, the commercial Ultimate Trough using U.S. conditions, has reduced in installed cost from $178/m2 to $152/m2. Both designs could be even cheaper with Chinese steel.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:41Z
      DOI: 10.1063/5.0085663
       
  • Proposal and assessment of a novel multigeneration system based on a
           supercritical CO2 Brayton cycle driven by a solar power tower plant

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      Authors: Kasra Mohammadi, Kody Powell
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Supercritical carbon dioxide (s-CO2) Brayton power cycles have been found as a promising candidate for integration with solar power tower plants. Waste heat recovery from s-CO2 Brayton power cycles is a very attractive way for generating multiple useful products. In this work, a novel multigeneration concept is proposed based on an s-CO2 recompression power cycle, driven by a solar power tower, to generate electricity, freshwater, cooling, and hot water for domestic applications concurrently. In the proposed system, the waste energy rejected from a s-CO2 recompression cycle with a 100 MWe capacity is recovered by a multi-effect distillation (MED) plant, a half-effect water-lithium bromide (H2O- LiBr) absorption chiller, and a CO2−water heat exchanger for the generation of freshwater, cooling, and hot water. The thermodynamic analysis results show that the minimum and maximum pressures of the s-CO2 recompression cycle that give the highest thermodynamic efficiency are 84 bar and 270 bar, respectively. For these pressures, if the mass flow of the heat source is split equally between the MED plant and absorption chiller and the system operates at full load condition, 1,366 m3/day freshwater and of 3,263 kW cooling effect can be generated. Also, 258 kg/s hot water at 55 °C can be generated for domestic applications. The study results demonstrate that the proposed hybrid multigeneration system is an attractive concept to generate multiple useful products and supply the growing demand of the residential sector in a clean manner.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:41Z
      DOI: 10.1063/5.0089228
       
  • Solar mirror control by image analysis

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      Authors: Daniela Fontani, Paola Sansoni, David Jafrancesco, Gianluca Marotta, Franco Francini
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The control of the profile on the surface of heliostats is crucial because the mirror can be imperfectly manufactured, and the distribution of solar irradiation on the receiver is sensitive to the curvature of the surface of the heliostat. In practice, irregularities in the surface of the heliostat introduce aberrations that contribute to enlarge the spot on the receiver and the resulting energetic losses depend on the collection characteristics of the solar plant. Since the solar field can be formed by thousands of mirrors, it is essential to have a quick and economical control method to be used during manufacturing operations and successively also in the field during installation. The proposed method of optical control is based on techniques of image analysis. It assesses the heliostat surface quality by means of the examination of the acquired image in comparison with a reference image. This on-site optical control could be applied on various mirror types. The application of this profile control requires only a photographic camera and a screen with a calibrated pattern. The main advantages are ease of application, low-cost equipment, and simplicity of processing.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:41Z
      DOI: 10.1063/5.0085783
       
  • Permitting for a Gen 3 pilot-scale sodium and molten salt system

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      Authors: Dimitri Madden, Kenneth Armijo, Rip Winckel
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The development of a Generation 3 Liquid-Pathway, Pilot-scale sodium and molten chloride salt concentrating solar power system at Sandia National Laboratories requires extensive permitting to ensure code and environmental safety & health compliance for nominal, safe operation. This includes permitting for National Environmental Policy Act, U.S. Airforce approvals, and abiding by the National Fire Protection Association Life Safety Code. This work also details the failure modes effects analysis procedures to address design engineering and administration controls for technical risks. To facilitate permitting and safety procedures, staged sodium spray and pool fire variants were demonstrated. Soda ash extinguishing agents were utilized to demonstrate fire mitigation by Fire Department personnel. For this work, temperature data was measured for characterizing sodium fire temperatures and the zone of influence to provide PPE level information to emergency response personnel.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:41Z
      DOI: 10.1063/5.0085662
       
  • Design considerations for commercial scale particle-based thermal energy
           storage systems

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      Authors: Jeremy N. Sment, Timothy Harvey, Kevin J. Albrecht, Clifford K. Ho, Murphy Davidson, Matthew Lambert, Bradley Bateman
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Particle-based heat transfer materials used in concentrating solar power systems benefit from gravity-fed arrangements such as vertically integrated components inside the receiver tower which can eliminate the need for conveyance machinery. However, the amount of particles required for commercial scale systems near 100 MWe can require towers with very thick walls that must be built with high-strength concrete. Cost models for particle-based receiver towers with internal particle storage are being developed in this work and compared to well-established cost models that have been used to estimate tower costs for molten salt systems with external storage tanks. New cost models were developed to accommodate the high-temperature applications required for CSP. Further research is needed to directly compare costs between tower-integrated and external storage. For now, a method is proposed to superimpose increased storage costs with existing molten salt CSP towers. For instances where suitable materials are unavailable or do not meet the structural requirements, ground based storage bins must be used in concert with mechanical conveyance systems. Ground based storage vessels have been shown to be consistent with low thermal energy storage cost and heat loss goals. Ground based storage vessels are well-established in industry.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:40Z
      DOI: 10.1063/5.0086995
       
  • Analysis of an integrated CSP-PV hybrid power plant

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      Authors: Yibekal Gedle, Mark Schmitz, Hans Gielen, Pascal Schmitz, Ulf Herrmann, Cristiano Teixeira Boura, Zahra Mahdi, Ricardo Alexander Chico Caminos, Jürgen Dersch
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      In the past, CSP and PV have been seen as competing technologies. Despite massive reductions in the electricity generation costs of CSP plants, PV power generation is - at least during sunshine hours - significantly cheaper. If electricity is required not only during the daytime, but around the clock, CSP with its inherent thermal energy storage gets an advantage in terms of LEC. There are a few examples of projects in which CSP plants and PV plants have been co-located, meaning that they feed into the same grid connection point and ideally optimize their operation strategy to yield an overall benefit. In the past eight years, TSK Flagsol has developed a plant concept, which merges both solar technologies into one highly Integrated CSP-PV-Hybrid (ICPH) power plant. Here, unlike in simply co-located concepts, as analyzed e.g. in [1] – [4], excess PV power that would have to be dumped is used in electric molten salt heaters to increase the storage temperature, improving storage and conversion efficiency. The authors demonstrate the electricity cost sensitivity to sub- system sizing for various market scenarios, and compare the resulting optimized ICPH plants with co-located hybrid plants. Independent of the three feed-in tariffs that have been assumed, the ICPH plant shows an electricity cost advantage of almost 20% while maintaining a high degree of flexibility in power dispatch as it is characteristic for CSP power plants. As all components of such an innovative concept are well proven, the system is ready for commercial market implementation. A first project is already contracted and in early engineering execution.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:39Z
      DOI: 10.1063/5.0086236
       
  • Interpolation vector formulas for reflection and refraction of metasurface

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      Authors: Minghuan Guo, Zhifeng Wang
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Metasurfaces have an artificial nanostructured interface with a subwavelength thickness that manipulates light by spatially arranging the meta-atoms which are the fundamental building blocks of the metasurface. The anomalous reflection and refraction of light from metasurfaces are modeled by the generalized laws of reflection and refraction. Such laws indicate that the transmitted and reflected light beams can be bent in arbitrary directions in their respective half-space depending on the direction and magnitude of the interfacial phase gradient, as well as the refractive indices of the surrounding media. Since matrix computations or vector analyses are quite powerful tools for simulations of light propagation through and the flux distribution over an optical surface by ray tracing, this paper provides a set of general formulas for the anomalous reflection and refraction vectors of the re-emitted light developed from the generalized laws of refraction and reflection which are similar to the concise formulas for reflection and refraction vectors governed by Snell’s law. The vector formulas are functions of the incidence vector, normal vector, and angle parameters of reflection and refraction. The fundamental angular interpolation formula with angles of azimuth and altitude and the rotational angular interpolation formula defined with radial angle and rotation angle to express the unit vectors of the generalized refraction and reflection are used to analyze metasurface refraction and reflection. The new vector formulas should be good tools for optical simulations and designs of planar metasurface solar concentrators in addition to the traditional solar concentrators.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:39Z
      DOI: 10.1063/5.0085702
       
  • Bi-objective optimization of sectorial cleaning policy for the solar
           fields of concentrating solar tower plants

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      Authors: Huy Truong-Ba, Michael E. Cholette, Giovanni Picotti, Giampaolo Manzolini, Ruizi Wang, Theodore A. Steinberg
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The reduction of energy production due to heliostat soiling causes generation losses and therefore reduces the contribution and competitiveness of CSP. The optimal cleaning plan for CSP plants must strike the proper balance between the cost for cleaning activities and revenue losses due to a reduced power production. However, uncertainty in future soiling rates, weather conditions, and electricity sale prices (e.g. due to electricity markets, uncertainty in future purchasing agreements) significantly complicate the cleaning optimization. To address these challenges, a bi-objective simulation- optimization approach is developed to optimize the cleaning policy to simultaneously minimize cleaning costs and expected generation losses in the presence of stochastic weather, dust. The outcome of the proposed approach is the optimal number of cleaning trucks and periodic cleaning schedule for non-dominating solutions (Pareto front), which may be used to study the sensitivity of the cleaning schedule to variations in electricity prices. The approach is applied to a case study for a CSP plant located in Woomera, South Australia. The results show that for electricity sale prices between 40-100 AUD/MWh, the optimal number of trucks is 3 and the total cleaning costs are sensitive to the number of trucks purchased, but not to the cleaning frequency. However, as electricity prices increase above 300 AUD/MWh, the total costs become quite sensitive to the cleaning frequency. Finally, a comparison of the simulation-optimization approach and a (simpler) deterministic optimization indicates that the latter approach is suitable for most practical electricity prices.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:39Z
      DOI: 10.1063/5.0085664
       
  • Enhancement of SunDial optical performance handling cosine and end losses

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      Authors: Rubén Abbas, María J. Montes, Javier Cano, Luis F. González-Portillo, Andrés Sebastián, Javier Muñoz-Antón, Antonio Rovira, Jose M. Martínez-Val
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      A new low-cost collector has been conceived for solar heat for industrial processes: the SunDial. This collector seeks cost reduction by means of an innovative design that must carefully address the important effects of cosine and end losses. An in-house Monte Carlo Ray Tracing code is used to asses these effects for different configurations: one only field where as wide as long (8 m) or two parallel fields 4 m wide and 8 m long, so that the total reflecting surface is the maintained. In addition, these configurations might be tilted or not. It results that a low tilt of the field might help to reduce importantly cosine losses, whereas in order to reduce end losses fields with higher length/width ratio are required. It is demonstrated that, for primary mirrors length of 8 m, the receiver length required in order to limit end losses to 10% of the impinging energy is between 8 m (two narrow fields tilted 10 deg) to 11 m (one wide horizontal field). This study leads to a design methodology that will be used in the construction of two prototypes that will be built for two different end-users in the framework of the H2020 project ASTEP (GA 884411).
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:39Z
      DOI: 10.1063/5.0085667
       
  • Preliminary exploration of simulation and control of supercritical CO2
           solar thermal power generation system

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      Authors: Feng Hu, Zhifeng Wang
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      In order to solve the basic problem of the supercritical carbon dioxide (S-CO2) Brayton cycle integrated with solar power tower (SPT) station which used solid particle solar receiver (SPSR), a new extremum-seeking control method was applied by manipulating the particle and S-CO2 mass inventory in the integrated system. By designing different system operation modes and corresponding control logic, then using this control method to carry on the dynamic simulation. The results show that power generation in summer and winter solstice by extremum-seeking control is improved by 2.1% and 1.6%, respectively. The results could be references for control strategies as well as the safe operation of the system.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:38Z
      DOI: 10.1063/5.0086637
       
  • A fast tool for receiver life estimation and design

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      Authors: Mark C. Messner, Bipul Barua
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      This paper describes a software tool for predicting the service life of a tubular panel solar receiver operating at elevated temperatures. The current version of the tool, available at https://github.com/Argonne-National-Laboratory/srlife as open-source software, provides full 1D, 2D, or 3D thermal and structural analysis and creep-fatigue service life prediction for a single material, Alloy 740H. Future version will include an expanded material library as well as heuristics designed to reduce the cost of the receiver analysis. The goal for this package is to become a part of a software stack, including solar field and thermohydraulic simulations, for optimizing receiver designs to meet service life and economic targets. These design and optimization frameworks could be crucial in producing viable high temperature receiver designs, operating at outlet temperatures targeting high efficiency energy conversion and storage systems.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:38Z
      DOI: 10.1063/5.0085669
       
  • Solar field experiences from Hami solar tower project

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      Authors: Thomas Keck, Joaquin Gracia, Iban Eizaguirre, Dengke Sun, Markus Balz, Jesus Iriondo
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The innovative and award-winning Stellio heliostat, so far only known from prototypes and pre-series with promising technical data, is being applied in a commercial solar tower project for the first time. While the partners in the Stellio Consortium have comprehensive know-how in CSP technology, the heliostat includes several novel solutions and the companies on the client side had little experience in this field. The implementation of the parts production, the heliostat assembly and installation and the commissioning are therefore a challenge, with the question being whether the outstanding quality of Stellio can be maintained in series production.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:38Z
      DOI: 10.1063/5.0086590
       
  • Techno-economic analysis of CSP incorporating sCO2 brayton power cycles:
           Trade-off between cost and performance

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      Authors: Dario Alfani, Ty Neises, Marco Astolfi, Marco Binotti, Paolo Silva
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Concentrating solar power (CSP) plants, thanks to the implementation of cost-competitive thermal energy storage, represent a dispatchable zero-emission alternative to traditional fossil fuel power plants. Next generation solar towers are expected to adopt high temperature receivers (>700°C) coupled to sCO2-based power blocks, which optimal design is generally pushed towards the maximum cycle efficiency, often neglecting the economic impact with the justification that the main share of the capital cost is represented by the heliostat field. As result, the scientific literature lacks in comprehensive studies on techno-economic evaluation of CSP+sCO2 power plants addressing the important correlation that exists between system cost and performances. This work provides a preliminary techno-economic analysis of a solar power tower comparing four different cycle configurations for the sCO2 power block. Results have been reported on a Pareto front, highlighting the tradeoff between the plant investment cost and the solar-to-electricity plant efficiency. The trends of the optimization variables and cycle results have been reported to give useful insights about proper assumptions for the sCO2 power block design. The recompressed cycle with intercooling resulted as the most promising configuration and it has been further analyzed through a comparison of different solutions on the Pareto front. The cost breakdown of the sCO2 power block has been reported to highlight which components have the greatest impact on the overall plant cost and how they vary along the optimal solutions front. Eventually, the optimization has been repeated introducing a correlation to compute the turbomachinery isentropic efficiencies, to investigate their effect on the techno- economic analysis.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:37Z
      DOI: 10.1063/5.0086353
       
  • Particle curtain temperature estimation through imaging techniques

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      Authors: Jesus D. Ortega, Clifford K. Ho, Guillermo Anaya, Peter Vorobieff, Gowtham Mohan
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The particle temperature measurements in gravity- and wind-driven flows present a unique challenge due to the flow’s transient and stochastic nature. While attempts to estimate the bulk particle temperature have been conducted using contact and non-contact methods, a definitive and practical solution is yet to be found. This work focuses on a novel non- contact method using a high-speed IR camera and a visible-light camera (Nikon D3500) to accomplish this indirect particle temperature measurement. The thermograms and image sets collected by the cameras allow for the measurement of the apparent particle temperature and the opacity of a particle plume. An in-house post-processing code based on Radiation law theory allows the calculation of the true particle temperature from the apparent temperature obtained from the thermograms. The particle temperature data are compared with the empirical model of the bulk particle temperature yielding agreement with the experimental measurements.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:37Z
      DOI: 10.1063/5.0086080
       
  • Molten salt vs. liquid sodium receiver selection using the analytic
           hierarchy process

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      Authors: Craig S. Turchi, Cara Libby, John Pye, Joe Coventry
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      An international team led by NREL analyzed the favorability of two alternative liquid receiver designs for a 700+ °C receiver under the Gen3 CSP Liquid Pathway project. The competing liquid heat transfer fluids were a ternary chloride salt and liquid-metal sodium. The team applied a facilitated analytic hierarchy process (AHP) to arrive at a recommended alternative and set a path forward for the project. The AHP criteria were formulated, weighted, and scored by the project leadership team and technical advisory committee consisting of energy industry and CSP experts. The six- month process culminated with a two-day workshop where the sodium alternative was deemed to have both a significantly higher benefit (19.3%) and a lower LCOE (11.4%), with only a slightly higher risk (∼3%) than the salt alternative. Consequently, a sodium-receiver design was selected for the Liquid Pathway project, where it will be used to charge a two- tank chloride salt thermal energy storage system.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:37Z
      DOI: 10.1063/5.0087043
       
  • High-performance stellio heliostat for high temperature application

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      Authors: Thomas Keck, Vanessa Schönfelder, Bernd Zwingmann, Fabian Gross, Markus Balz, Frederic Siros, Gilles Flamant
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      High-temperature energy conversion processes and the corresponding high surface temperatures of receivers increase thermal losses. This makes high-performance heliostats with increased optical and tracking quality interesting. Several improvement measures were investigated for the Stellio heliostat (Figure 1). Performance gains and cost effects were examined for each measure and for a combination of all measures. LCoE changes have been calculated to assess cost- effectiveness.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:37Z
      DOI: 10.1063/5.0086592
       
  • QDec-M-Line: A geometric quality control system to assess fully assembled
           parabolic trough modules in series production

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      Authors: Steffen Ulmer, Benjamin Brix, Henning Koch, Andreas Kämpgen
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      A new inline measurement system for automatic quality assurance of the concentrator shape of parabolic trough modules in series production has been developed. The applied deflectometry measurement technique is based on the iterative reflection of an illuminated movable pattern in the mirror surface and its distortion due to mirror surface deviations. The movable pattern can be realized conveniently by making use of a gantry crane typically utilized in parabolic trough module production workshops. The measurement system was built and extensively tested on laboratory scale. All relevant effects on the slope measurement accuracy, reliability and dependency on harsh ambient conditions were thoroughly analyzed. All required features for the upscaling to full parabolic trough module size and for flexible adaption to different geometries are available. The here presented progress in the development of the system and the results of the validation measurements demonstrate its readiness for an industrial scale implementation.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:36Z
      DOI: 10.1063/5.0085706
       
  • Hydrogen monitoring and control in the heat transfer fluid of parabolic
           trough plants

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      Authors: Christian Jung, Carsten Spenke
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      In this study hydrogen concentrations in the heat transfer fluid (HTF) of parabolic trough systems were analyzed and hydrogen control by venting was practically tested in several plants. Concentrations between 10 and 800 µmol/kg and decreases of hydrogen by venting between 10 - 75% were found. A model consideration is presented that clearly demonstrates the impact of equilibrating HTF from the solar field with the fluid in vessels on hydrogen concentration. Concentrations could be reduced more than 80% in the solar field if equilibrium of the gas with gas spaces in vessels was achieved. Hydrogen formation rates of used HTF with up to nine years of service life were checked with lab tests. These indicate increasing hydrogen formation of up to eightfold compared to unused fluid which gives rise to re-consider recommendations of maximum tolerable concentrations of low and high boilers in used eutectic mixtures of biphenyl and diphenyl oxide.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:36Z
      DOI: 10.1063/5.0085825
       
  • Effect of the cyclic heating (aging) on the solar absorptance and specific
           heat of particulate materials

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      Authors: Rageh S. Saeed, Abdulelah Alswaiyd, Hany Al-Ansary, Abdelrahman El-Leathy, Sheldon Jeter, Shaker Alaqel, Nader S. Saleh, Eldwin Djajadiwinata, Zeyad Al-Suhaibani, Syed Danish, Zeyad Almutairi
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Using solid particles as a heat transfer media (HTM) in concentrated solar power applications gained growing attention lately. Unlike molten salt, solid particles offer high operating temperatures (greater than 1000°C), no freezing issues, abundantly availabile, high thermal energy storage capacity, low-cost, non-corrosive, and applicability of direct irradiation. Comprehensive knowledge of thermophysical and optical properties of solid particles is essential to ensure an effective harnessing of solar energy. The most important considerations when selecting solid particles include (1) thermophysical and optical properties, (2) thermal resistance, (3) crack resistance (4) satisfactory health and safety risks (5) availablity, and low-cost. It is also imperative to consider optical and thermophysical characteristics that might change from what they were as received after cyclic heating for a long time. Therefore, the knowledge of the thermal performance of particulate materials becomes significant before using them as HTM. In this study, some particulate materials have been chosen to study their feasibility to be used as heat transfer and storage media for the particle-based central receiver tower system. These particulate materials include red sand, white sand, ilmenite and carbobead CP. The cyclic heating was performed on the particulate materials for 500 hours at 1200°C. Weighted solar absorbtance and specific heat have been measured for the candidate particulates as received and after cyclic heating (aging) for a specified duration of time.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:35Z
      DOI: 10.1063/5.0085828
       
  • Solar-driven indirect calcination for thermochemical energy storage

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      Authors: Carlos Ortiz, Juan Valverde, Carlos Tejada, Andrés Carro, Ricardo Chacartegui, José Manuel Valverde, Luis Perez-Maqueda
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      A novel integrated model is used to evaluate the technical feasibility of a large scale Concentrating Solar Power (CSP) plant with thermochemical energy storage based on the Calcium-Looping (CaCO3/CaO) process. Instead of using a solar particle receiver to carry out the calcination of limestone, as the usual solution considered in previous literature, this work proposes an indirect calcination system based on using a pressurized Heat Transfer Fluid (HTF) heated up inside a tubed volumetric cavity receiver, to heat indirectly the particles for calcination to take place in an Entrained Flow (EF) reactor. After the reactor, the HTF follows a typical closed combined cycle path for power production before entering again in the receiver. On the other hand, the CaO particles and CO2 are stored for power production under demand. Results show that full calcination of 10 kg/s can be achieved in a 51 m length and 2.5 m diameter downer reactor from an HTF releasing 17.2 MWth at temperatures higher than 1100°C. This opens a promising research line for the development of systems based on materials calcination from renewable energies.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:35Z
      DOI: 10.1063/5.0085705
       
  • Laboratory prototype of an innovative radial flow packed bed thermal
           energy storage

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      Authors: Silvia Trevisan, Wujun Wang, Rafael Guédez, Björn Laumert
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      This work presents a laboratory scale 50kWhth prototype of an innovative radial flow packed bed thermal energy storage. The proposed storage has an inward radial heat transfer fluid flow during charge and a reverted fluid flow, by means of a valve arrangement, during discharge. The storage unit is equipped with differential pressure gauges, mass flow controller and 50 K-thermocouples to accurately measure the thermodynamic behavior of the unit. In order to assess the performance of the proposed thermal energy storage design two specific indicators have been introduced and defined, namely: the temperature uniformity, and the hydrodynamic uniformity. The results of preliminary CFD studies show a maximum temperature deviation of 20°C along the storage axial direction and uniformity indexes higher than 90%.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:35Z
      DOI: 10.1063/5.0086004
       
  • Effect of solar field aiming strategies on the fatigue life in molten salt
           external central receivers

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      Authors: Richard Rangel, David Acosta, Jesús García, Marco Sanjuan, Rodrigo Barraza, Habib Zambrano
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The influence of two operations modes in the solar field of a molten-salt power plant was investigated to evaluate how the receiver pipes’ fatigue life changes. Temporal and spatial DNI variation from the WobaS system were integrated with STRAL to obtain the energy flux that heats the working fluid. The temperature distribution over the pipe was obtained by solving a steady-state 3D partial differential equation, validated with a literature model with a 0.1% deviation. The fatigue analysis is based on the elastic behavior assumption. So, the rainflow counting methodology was implemented to consider the irregular sets of equivalent stresses the receiver pipe faced over the transient period. An estimation of the cycles to failure was obtained, and neither operation mode caused fatigue failure before 106 cycles. Still, the controlled aiming point strategy was able to gain an average of 378 MWth over the Solar Two operation mode, where the molten salt would be redirected to the cold tank.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:34Z
      DOI: 10.1063/5.0085673
       
  • Adoption of CO2 blended with C6F6 as working fluid in CSP plants

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      Authors: Giampaolo Manzolini, Marco Binotti, Ettore Morosini, David Sanchez, Francesco Crespi, Gioele Di Marcoberdino, Paolo Iora, Costante Invernizzi
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The adoption of CO2-based mixtures as power block working fluid for CSP plant can turn supercritical CO2 cycles into efficient transcritical cycles even at high ambient temperature, with significant performance improvement and potential power block cost reduction. In this work, the use of CO2+C6F6 mixture as working fluid for a power cycle coupled with a solar tower is analyzed. Two different cycle maximum temperatures (550°C and 650°C) are considered and for both configurations the overall plant design is performed. The yearly energy yield is computed with hourly data and the LCOE is minimized varying storage and cycle recuperator sizes. Results show comparable results for the innovative working fluid and for the sCO2 cycles.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:34Z
      DOI: 10.1063/5.0086520
       
  • Performance of a CPC inserted in a high vacuum envelope

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      Authors: Carmine D’ Alessandro, Davide De Maio, Daniela De Luca, Marilena Musto, Emiliano Di Gennaro, Roberto Russo
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Evacuated flat thermal systems equipped with a Compound Parabolic Concentrator (CPC) represent a solar thermal architecture useful to meet the growing world demand for mid-temperature heating. The performance of such a system could be improved by coating the inner side of the encapsulating glass with a selective InfraRed (IR) mirror. The underlying physical mechanism is the cold-side external photon recycling, which allows to recover the power radiated by the absorber and, consequently, to increase the solar thermal efficiency. By means of a thermal model and numerical simulations, here we demonstrate how the mirror sensibly influences the panel performance: despite a transmittance drop in solar wavelengths that affects the efficiency below 250 °C, efficiency increases are achieved at higher temperatures.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:34Z
      DOI: 10.1063/5.0086369
       
  • Developments in solar heat from concentrating solar systems

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      Authors: Dirk Krüger, Bärbel Epp, Tobias Hirsch, Martina Neises-von Puttkamer
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Industrial heat applications are a significant market for concentrating solar technologies. Currently, concentrating collector technologies are offered by a number of suppliers. This publication gives an overview on the installations which have been built recently in terms of capacity, application and country. Several examples show combinations with storage, different heat transfer media and a large collector field for district heating. Facilitating financing is possible by ESCOs (Energy Service Companies) and collector certification according to ISO9806.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:34Z
      DOI: 10.1063/5.0085794
       
  • Novel design of the solar disinfectant closet (device) for inactivation of
           COVID-19 virus

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      Authors: Atul A. Sagade, Rodrigo Palma-Behnke
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Solar drying is one of the important application of out of several applications of solar thermal technologies. Solar drying is generally preferred for the drying of different agricultural products and several designs of such dryers are developed and investigated around the globe. However, the solar dehydration/disinfection of the cloths/utensils (clothes drying rack/device) and development of appropriate designs for the same is one of the neglected aspect. Such designs of “solar cloth dehydrators and/or devices” may play an important role in the humid and cloudy weather conditions. More importantly, in the present pandemic of COVID 19, solar dehydrators/disinfectors can be a crucial device for disinfection of cloths and other utensils. Thus, the present work is aimed to design, develop and investigate the novel design of Solar Disinfectant Closet (SDC)/Solar Disinfection Device (SDD) for inactivation of COVID-19 Virus (SARS-COV-2). A primary small prototype of SDC/SDD made of metallic structure is designed and fabricated which can be used during day as well as night. The present design of SDC/SDD is manufactured taking into account the heat inactivation protocol of 5- log viral load reduction (56°C-30min and 60°C-60min) and can be modified to follow the protocol 6-log viral load reduction (92°C -15min). The present experiments discusses the disinfection of stainless steel utensils (SSUs) using the proposed device. The primary results depicts that the novel design of SDC/SDD can reach a temperature of 70°C within 30 minutes and able to dehydrate/disinfect the rated load of cloths/utensils in short span of 70 to 90 minutes. It is proposed that the same device can be used for the inactivation for the different crucial viruses like Tuberculosis, Influenza etc.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:33Z
      DOI: 10.1063/5.0085676
       
  • Optimized solar absorber coating for a new concentrating solar collector
           under high vacuum

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      Authors: Davide De Maio, Carmine D'Alessandro, Antonio Caldarelli, Marilena Musto, Roberto Russo
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      A compound parabolic concentrator (CPC) inserted in a flat high vacuum envelope is a novel architecture of solar thermal collectors suitable for mid-temperature applications (200 °C - 400 °C). This novel thermal panel uses very low concentration factors and in commerce there is a lack of selective absorbing coatings properly designed for this purpose. In the present work a multilayered coating has been numerically simulated and its thicknesses have been optimized to increase the overall solar-to-thermal efficiency of the device. It consists of Cr2O3 − Cr - Cr2O3 multilayer deposited on a copper substrate and covered with an SiO2 Anti-Reflective (AR) coating. In order to effectively maximize the thermal conversion efficiency, the absorber infrared emission has been taken in the right consideration with respect to solar absorption. The comparison with the adoption of a commercial coating reveals a sensible improvement in the overall thermal efficiency, increasing the working temperature up to 400 °C.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:33Z
      DOI: 10.1063/5.0086368
       
  • Design and modeling of a three-dimensional compound parabolic
           concentrator(3D-CPC) of a 10 kWe solar tower plant

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      Authors: Ababacar Ibrahima, Elhadji Ibrahima Cissé, Mohamed Ngom, Baye Alioune Ndiogou, Mohamed S. Adjibade
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      This work presents the design and analysis of the optical performance of a 3D-CPC of a 10 kWe solar micro- tower in the Sahelian zone. The tower consists of a field of 60 heliostats of 2 m2 and a receiver with a CPC of height equal to 18 m and inclined at an angle of 45 °. The CPC is dimensioned from an opening radius corresponding to the radius of concentrated solar flux of the heliostats field. This work presents on the one hand a method to model the 3D-CPC from its characteristics and on the other hand an approach to incorporate a complex geometry like the 3D-CPC in Monte Carlo ray tracer Soltrace. The simulation results show that the optical performance of the tower improves with the presence of the CPC which increases the solar flux at the receiver entrance while reducing the opening area of said receiver. The average concentration ratio of 3D-CPC is equal to 4.7.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:33Z
      DOI: 10.1063/5.0086127
       
  • Wash vehicle fleet sizing for contingency planning against dust storms

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      Authors: Alexander Zolan, Mark Mehos
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Wash vehicles containing either high- or low-pressure water sprayers, a collection of rotating brushes, or a combination of these, are frequently utilized in concentrating solar power (CSP) plants to maintain a high level of optical efficiency in the solar field. In recent years, multiple modeling approaches have been developed to obtain fleet sizes and mirror-washing schedules that optimize the tradeoff of vehicle capital and use costs and labor versus lost revenues due to soiling. These planning models cover normal operating conditions well but do not consider rare events such as dust storms which can cause a significant reduction in receiver productivity, or shut down operations until most or all of the solar field’s mirrors have been cleaned. To that end, we propose a methodology that evaluates whether additional capital should be deployed to hedge against these events by weighing the net present value of the expected benefits against the capital costs. The output of this method is a breakeven frequency, a metric we sue to determine whether an additional vehicle should be purchased to address the contingency of dust storms by comparing it to the expected annual storm frequency We develop a small collection of case studies using commercial-scale CSP tower plants and obtain breakeven frequencies that mostly fall between 0.1 and 1.0 storms per year, depending on the existing fleet size and storm severity.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:32Z
      DOI: 10.1063/5.0085675
       
  • Accelerated aiming strategy in central receiver systems using integer
           linear programming

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      Authors: Pascal Richter, Nils Speetzen
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Aiming strategies are used to distribute the heat flux on the receiver surface with the aim to maximize the mass flow of the heat transfer fluid in the receiver tubes while avoiding thermal overloading. The optimization problem is modeled as an integer program (IP) to provide deterministic solutions. To improve the runtime, several accelerations are investigated as the grouping of heliostats to reduce the size of the optimization problem. In a case study we show that an optimal solution can be found within seconds while maintaining high accuracy.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:31Z
      DOI: 10.1063/5.0085711
       
  • Stowing strategy for a heliostat field based on wind speed and direction

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      Authors: Matthew Emes, Azadeh Jafari, Mike Collins, Stefan Wilbert, Luis Zarzalejo, Silvan Siegrist, Maziar Arjomandi
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      This paper investigates a stowing strategy of a heliostat field based on wind speed and direction, in terms of the potential benefit of additional energy collection through the partial stowing of heliostats within an azimuth angle range with reduced operating wind loads. Correlations of one-minute wind speed and DNI at a heliostat field site with the operating wind loads, based on the azimuth-elevation tracking angles of individual heliostats, were used to assess the increased operating time and collected thermal energy by the field. The results show that more than 23% of heliostats in the sector of the field with operating wind loads that are smaller than 50% of the stow loads can continue to operate during a high-wind period (e.g. 10 m/s). Adopting a stow strategy based on wind direction can increase the annual operating time of the heliostat field by 6% with increasing stow design wind speed from 6 m/s to 12 m/s. Furthermore, the stowing strategy based on wind direction to allow heliostats to continue to operate at wind speeds exceeding 10 m/s can achieve an additional 280 MWh of thermal energy collected by the heliostat field operation during time periods that would conventionally stow the entire field with 24 GWh of annual thermal energy captured.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:31Z
      DOI: 10.1063/5.0085677
       
  • Using concentrated solar energy in a biomass gasification to produce
           hydrogen

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      Authors: Shahid H. Ansari, Jianqi Shen, Xinying Liu
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Biomass gasification is an endothermic process which can be used to produce hydrogen (H2). This study presents a simulation model using ASPEN Plus® to design biomass gasification process with water gas shift reaction (WGSR) to obtain maximum H2. This was done by optimizing the process conditions via. modeling to understand the fundamental of the gasification process. Gibbs free minimization and thermodynamics equilibrium approach was used to find out best operating conditions for H2 production. After conditioning of syngas, WGSR at 200°C was introduced to produce H2 as an alternative fuel. Both steam and CO2 as gasification agents were investigated. The effect of temperature and flowrate of steam and CO2 were optimized in such a way so that no solid carbon produced in the syngas. Higher temperature is favorable while temperature higher than 800°C has an adverse effect on H2 yield. The aim of present study is to determine H2 production per kg of biomass feed and H2 productivity per MWth solar-thermal energy input to the gasification system.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:31Z
      DOI: 10.1063/5.0085710
       
  • Assessment of Ti3SiC2 MAX phase as a structural material for high
           temperature receivers

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      Authors: Bipul Barua, Mark C. Messner, Dileep Singh
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Designing next generation concentrated solar power plant solar receivers with current metallic alloys is extremely challenging due to high creep damage accumulation under high temperature operating conditions. New structural materials with high creep resistance must be sought to achieve a desired design life of 30 years to recover the plant capital cost. MAX Phase materials are known to exhibit high creep resistance as well as high fracture toughness and therefore could be a viable option for high temperature receiver designs. This work assesses Ti3SiC2 MAX Phase as a potential candidate for high temperature receivers through evaluating the creep-rupture life of a reference molten salt receiver. Assessments are made for two different grain sizes – a fine-grained (3-5 µm) and a coarse-grained (∼ 30 µm) Ti3SiC2 MAX Phase. Results indicate a design life of several tens of years can be achieved for the reference receiver using Ti3SiC2 MAX Phase compared to less than a year design life using a high temperature nickel based alloy A740H.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:30Z
      DOI: 10.1063/5.0085952
       
  • On-sun experiments on the world’s first deployed gas-turbine
           particle-based power tower facility at King Saud University

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      Authors: Shaker Alaqel, Eldwin Djajadiwinata, Nader S. Saleh, Rageh S. Saeed, Abdulelah Alswaiyd, Hany Al-Ansary, Abdelrahman El-Leathy, Sheldon Jeter, Syed Danish, Zeyad Al-Suhaibani, Said Abdel-Khalik
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The current paper presents experimental observations on the particle-based integrated gas turbine-solar heating system located on the campus of King Saud University in Riyadh, Saudi Arabia. The system was built to achieve three primary outcomes: (1) use the concentrated solar energy to raise the particle temperature to more than 600°C. (2) achieve a significant solar contribution, which can help in limiting fossil fuel consumption. (3) demonstrate the ability to store the thermal energy in the solid particles for later use. However, only two objectives have been fulfilled; due to some deficiencies and limitations in the current system, the first objective has been successfully fulfilled while the second is partially fulfilled. The paper outlines the system deficiencies and the imperative recommendations towards efficient execution of the system. The system deficiencies mentioned above include the heat loss on PHR due to exposure to the wind, particle agglomeration tendency on some regions of the PHR, heat loss while charging the thermal energy storage, and heat loss during particle circulation. However, despite all deficiencies above, the system was able to bring the particle temperature (red sand particles) to more than 600°C. Furthermore, the results show that harnessing solar energy is possible if such deficiencies were overcome. In general, the results are encouraging, and additional precautions are currently added to the system to push the particle temperature even higher and achieve higher solar contribution.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:30Z
      DOI: 10.1063/5.0085831
       
  • Heliostat innovation in detail to reach challenging cost target

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      Authors: Andreas Pfahl, Hicham Bouzekri, Abdelali Djdiaa, Daniel Benitez, Vincent Nettelroth, Jens Rheinländer, Andreas Krause
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      To be able to achieve the challenging cost targets for heliostat fields, several innovations in detail for a carousel type heliostat were developed. The resulting cost reduction and local content are estimated. First conclusions from a Moroccan-German project that aims to increase the local added value of heliostat production are drawn.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:30Z
      DOI: 10.1063/5.0086922
       
  • Low-cost movable heliostat

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      Authors: Andreas Pfahl, Amadeus Rong
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Movable heliostats avoid the rail systems of rotating heliostat fields. They can be realized cost effectively by modifying low-cost carousel type heliostats. The cost for the modifications is estimated and compared to the savings resulting from the higher efficiency.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:30Z
      DOI: 10.1063/5.0086923
       
  • Particle-to-sCO2 heat exchanger experimental test station design and
           construction

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      Authors: Hendrik F. Laubscher, Kevin J. Albrecht
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Design and construction of a particle-to-sCO2 heat exchanger test station is described in this paper. The purpose of this test station is to make steady-state measurements of thermal performance with sCO2 as the working fluid. While the test station was initially constructed to test a 20 kW heat exchanger developed under the Gen3 Particle pilot plant (G3P3) project, it also was designed to accommodate testing of other heat exchanger configurations. Improvements for this test station design is based on lessons learned from prior heat exchanger testing. Maximum pressure and temperature ratings are based on the desire to use primarily stainless steel in the construction to reduce cost and lead time of components. Construction of the test station was completed and commissioning and initial testing took place during the October to November 2020 timeframe.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:29Z
      DOI: 10.1063/5.0085954
       
  • Compact system for fast on-line geometry characterization of facets for
           solar concentrators

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      Authors: B. Ahmed Chekh, Jesús Fernández-Reche, Loreto Valenzuela, Cristobal Villasante, Gorka Kortaberria, Diego Pulido-Iparraguirre
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      This paper presents an alternative in process quality control inspection system for facets (mirrors) of an optical concentrator. The knowledge of the geometrical shape of these optical surfaces is crucial to ensure a suitable performance of the solar collector. Currently close-range photogrammetry or deflectometry techniques are available to measure the geometry of solar reflectors, where the measurement preparation and processing times are important limitations for high ratio production quality control. The alternative inspection solution depicted in this paper is the application of an inline control system of solar reflectors based on the autocollimation principle which has been conceived in Tekniker. This system has been adapted to measure linear Fresnel reflectors (LFR) in this project. In the work carried out a measurement of a set of linear Fresnel reflector units facets have been performed to validate the implementation of the autocollimators cell in the Plataforma Solar de Almeria (CIEMAT-PSA). Differences in the mrad order between the current photogrammetric approach and the proposed autocollimator based cell solution are obtained, validating the suitability and feasibility of this system for the facet inspection with high production rates.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:29Z
      DOI: 10.1063/5.0086360
       
  • A thermal model for a CPC-Type double-pass solar air heater

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      Authors: Irving A. Chávez-Bermúdez, Naghelli Ortega-Avila, Eduardo Venegas-Reyes
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The double-pass solar air heater consists of a linear CPC with a flat receiver, where the air circulates counterflow through the cavity formed by the absorber plate, the cover, and the reflectors to preheat the fluid and then incorporate it into the receiver duct. This research's objective was to demonstrate that the CPC-type double-pass heater's thermal performance is better than a conventional or single-pass CPC heater. In this sense, two one-dimensional steady- state thermal models were developed, one for each CPC-type heater. The heat transfer equations were solved in the cover, the cavity, the absorber plate, and the receiving duct, using the numerical method of control volumes. Both models were evaluated for a truncated concentrator, with a mass flow range of 0.0013 kg/s to 0.1050 kg/s, setting the global solar irradiance at 950 W/m2, the wind speed 3 m/s, and the ambient temperature and the inlet temperature of the fluid at 33 °C. In all the cases analyzed, the double pass heater provides higher outlet air temperature and instantaneous efficiency than the conventional ones, with improvements until 9.4% and 73.1%, respectively. In the double pass air heater, the air temperature at the concentrator outlet was 88.4 °C (with laminar flow in the receiving duct) to 37.8 °C (with turbulent flow), instantaneous efficiency was 7.3% to 59.0%. Based on the results obtained, it is concluded that the CPC-type double pass solar air heater allows the profiteering of the heat lost by the receiver from the pre-circulation of air through the cavity.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:29Z
      DOI: 10.1063/5.0086083
       
  • LIDAR for heliostat optical error assessment

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      Authors: Charles Q. Little, Daniel E. Small, Julius Yellowhair
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      This project extends Sandia’s experience in Light Detection And Ranging (LiDAR) to gain an understanding of the abilities and limits of using 3D laser scanning to capture the relative canting angles between heliostat mirror surfaces in 3D space to an accuracy sufficient to measure canting errors. To the authors’ knowledge, this approach has never been developed or implemented for this purpose. The goal is to be able to automatically perform a 3D scan, retrieve the data, and use computational geometry and a-priori mechanical knowledge of the heliostats (facet arrangement and size) to filter and isolate the facets, and fit planar models to the facet surfaces. FARO FocusS70 laser range scanners are used, which provide a dense data coverage of the scan area in the form of a 3D point-cloud. Each point has the 3D coordinates of the surface position illuminated by the device as it scans the laser beam over an area, both in azimuth and elevation. These scans can contain millions of points in total. The initial plan was to primarily use the back side of the heliostat to capture the mirror (the back side being opaque). It was not expected to capture high-quality data from the reflective front side. The discovery that the front side did, indeed, yield surface data was surprising. This is a function of the soiling, or collected dust, on the mirror surface. Typical point counts on the mirror facets are seen to be between 10k – 100k points per facet, depending on the facet area and the scan point density. By collecting facet surface points, the data can be used to calculate an individual planar fit per facet, the normals of which correlate directly with the facet pointing angle. Comparisons with neighboring facets yield the canting angles. The process includes software which automatically: 1) controls the LiDAR scanner and downloads the resultant scan data, 2) isolates the heliostat data from the full scan, 3) filters the points associated with each individual facet, and 4) calculates the planar fit and relative canting angles for each facet. The goal of this work has been to develop this system to measure heliostat canting errors to less than 0.25 mrad accuracy, with processing time under 5 minutes per heliostat. A future goal is to place this or a comparable sensor on an autonomous platform, along with the software system, to collect and analyze heliostats in the field for tracking and canting errors in real time. This work complements Sandia’s strategic thrust in autonomy for CSP collector systems.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:29Z
      DOI: 10.1063/5.0087691
       
  • Towards a design framework for non-metallic concentrating solar power
           components

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      Authors: Mark C. Messner, Bipul Barua, Dileep Singh
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      This paper describes a framework for the design of non-metallic concentrating solar power components. The next generation of solar receivers may be required to withstand material temperatures in excess of 800( in order to increase energy conversion and storage efficiency. At these temperatures, even high temperature Ni-based alloys may not provide practical, economic designs. Ceramics and other non-metallic materials have the required strength at these temperatures, but component design approaches for these materials must consider a different set of failure modes and mechanisms, when compared to metals. This paper outlines existing, applicable design methods and provides a draft set of discriminatory categorization tests aimed at placing non-metallic materials in categories with well-established existing design methods. However, the paper notes the existence of a category of high temperature materials – brittle or quasi-brittle materials with time-dependent strength – where there are no well-established design rules. A statistical design process for these types of materials is outlined here, though developing this outline into a practical design method will require substantial additional work.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:28Z
      DOI: 10.1063/5.0085670
       
  • Techno-economic analysis of hybrid supercritical CO2 based molten salt
           tower CSP-PV

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      Authors: Silvia Trevisan, Rafael Guédez, Björn Laumert
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The present work performs a techno-economic analysis of a hybrid CSP – PV plant composed of a molten salt tower CSP running a supercritical CO2 power unit and a PV field. The two plants are connected in parallel, behind the meter. The PV unit produces power during daylight. The CSP plant stores thermal energy during the day to enable stable production during cloudy periods and enlarges the plant capacity factor while producing during the night. The plant performances have been evaluated in terms of capacity factor, thermal energy storage utilization factor, capital expenditure, and Levelised Cost of Electricity. The influence of plant solar multiple, storage size, supercritical CO2 nominal size, PV relative nominal size, receiver thermal efficiency, CO2 power unit, and PV cost assumptions has been assessed through different sensitivity analyses. The results show that it is worth hybridizing the system, indeed the PV unit can provide low-cost renewable power during the day, while the CSP unit can provide a cheap storage technology. Plant configurations leading to a Levelised Cost of Electricity lower than 70 $/MWhe can be identified already at relatively low nominal power size, 15 MWe. The receiver thermal efficiency is shown to be a highly important assumption, highlighting the need for further component development.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:28Z
      DOI: 10.1063/5.0086002
       
  • An efficient method for aiming heliostats using ray-tracing

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      Authors: Shuang Wang, Charles-Alexis Asselineau, John Pye, Joe Coventry
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      In a solar power tower plant, the role of the heliostat aiming strategy is to control the radiative flux distribution at the receiver surface to avoid thermally induced damage, while minimising spillage losses. Flux limitations arise from factors including the heat transfer fluid stability limits, and thermo-mechanical stress limits in receiver pipes. To accurately determine receiver flux distributions, ray-tracing is preferred, although it is more computationally expensive than convolution-based methods. In this study, we introduce a new parameterisation of heliostat aim-point locations that significantly reduces the number of parameters to determine. The new aiming model enables efficient use of ray-tracing to optimise the aiming strategy and, together with receiver thermal and mechanical models, is able to closely match the flux distribution to local values of allowable flux on the receiver. A reference case with a surround field and a cylindrical external receiver compatible with the Gen3 Liquid Pathway project is presented to test the capability of the method developed in this study.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:28Z
      DOI: 10.1063/5.0085672
       
  • Solar-aided calcination of limestone: First modeling of the SOLCEMENT
           process

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      Authors: Athanassios Nikolakopoulos, Theodore Steriotis, Georgia Charalambopoulou, George Karagiannakis, Dimitrios Dimitrakis, Athanasios G. Konstandopoulos, Vasileios Michalis, Marios Katsiotis
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Cement production is one of the most energy intensive industrial processes, accounting for approximately 5% of the total CO2 emissions worldwide; about 2/3 of such emissions are due to limestone calcination. The SOLCEMENT process pertains to the use of concentrated solar radiation for limestone calcination in cement plants. The process employs also a thermochemical storage reactor (TSR) integrated into the conventional solids preheating system, to partially compensate for the intermittent nature of sunlight, by enabling the transfer of stored solar energy to night operation thereby reducing the use of fossil fuels. In addition to fossil fuels replacement during daytime, the partial solarization of limestone calcination has the potential of CO2 recovery produced by the chemical reaction in pure form. A first detailed flowsheet of the integrated process is presented and reveals the possibility to transfer daily 28-52 MWh of solar energy between day and night operations for a 2.4 kt/day limestone calcination capacity cement plant. The study adopts a Process Systems Engineering approach which involves process modeling and optimization of design and operating parameters, towards maximization of solids’ temperature (up to 850 °C) after preheating, as well as optimal loading and use of the TSR (up to 6 MW). Four operating scenarios were considered, and show that the process performance scales with the temperature of the calciner flue gases, saving 52 MWh for 1000 °C, which accounts for ∼6% of the total required energy during non-solar operation (∼856 MWh).
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:28Z
      DOI: 10.1063/5.0085791
       
  • SWIPH, SAM wrapper for industrial process heat models

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      Authors: Miguel Frasquet, Juan Aramburo, Manuel Silva
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Since January 2017, SAM includes models for simulating concentrating collectors in industrial process heat applications (IPH). These IPH models are based on the more complex Concentrated Solar Power (CSP) models already available in SAM. Adapting the inputs of the IPH models to represent real industrial applications is difficult and often leads to convergence errors. SWIPH is a decision support tool that simplifies the entry of input variables needed in SAM's IPH models. In addition to providing default values for the industry sector selected, SWIPH uses supervised classification algorithms to predict if the combination of inputs introduced by the user leads to a converge error. When that is the case, it suggests the closest set of input variables that produces a valid simulation. SWIPH is able to predict with 94% accuracy whether the given inputs will produce a valid simulation or on the other hand, what kind of error would it raise.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:28Z
      DOI: 10.1063/5.0086121
       
  • Development of an aerial imaging system for heliostat canting assessments

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      Authors: Julius Yellowhair, Pavlos A. Apostolopoulos, Daniel E. Small, David Novick, Micah Mann
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The heliostat collector field is the front-end of large solar power tower plants. Any negative performance impacts on the collector field will propagate down the stream of subsystems, which can negatively impact energy production and financial revenues. An underperforming collector field will provide insufficient solar flux to the receiver resulting in the receiver running at below capacity and not producing the thermal energy required for thermal storage and to run the power block at optimum efficiency. It is prudent to have an optimally operating collector field especially for future Gen3+ plants. The performance of a deployed collector field can be impacted by mirror quality (surface and shape), mirror canting errors, tracking errors, and soiling. Any of these error sources can exist during installation and further degrade over time and, if left unattended, can drastically reduce the overall performance of the plant. Concentrating solar power (CSP) plant operators require information about the collector field performance to quickly respond with corrections, if needed, and maintain optimum plant performance. This type of fast response is especially critical for future Gen3+ plants, which require high collector field performance consistently. However, power tower operators have struggled with finding or developing the right tools to assess and subsequently fix canting errors on in-field heliostats efficiently and accurately. Sandia National Laboratories National Solar Thermal Test Facility (NSTTF) is developing an aerial imaging system to evaluate facet canting quality on in-situ and offline heliostats. The imaging system is mounted on an unmanned aerial system (UAS) to collect images of targets structures in reflection. Image processing on the collected images is then performed to get estimates of the heliostat canting errors. The initial work is to develop the system definition that achieves the required measurement sensitivities, which is on the order of 0.25-0.5 mrad for canting errors. The goal of the system is to measure heliostat canting errors to
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:27Z
      DOI: 10.1063/5.0087057
       
  • Concentrating solar systems in moderate climates

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      Authors: Dirk Krüger, Stephan Fischer, Tobias Hirsch, Javier Iñigo Labairu
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The general perception for the application of solar concentrating collectors in moderate climates as in Central Europe and similar areas in the world, is that their energy yield is not sufficient. Clearly, the Direct Normal Irradiation (DNI) of 1000 kWh/(m² *a) is significantly lower than in sunny areas where it amounts to 2000 kWh/(m² *a) or even more. Nevertheless, if compared with stationary collectors, line focusing collectors can deliver heat at a comparable level but at higher operation temperatures. Simulations with two different tools were performed to calculate the annual energy yield from parabolic trough collectors for temperatures between 50 and 100°C, to benchmark with stationary collectors, which are commercially successful. For a variety of moderate sites worldwide parabolic trough collectors deliver the same amount of heat as stationary collectors at operation temperatures around 75°C. The amount of costs are still difficult to obtain for parabolic trough collectors. For solar plants installed and commissioned, costs for efficient collectors are reported 230 to 300 €/m² for field sizes of 10.000 m². Troughs can already be competitive at operation temperatures below 100°C. Thus if stationary collectors are successful in a market, there is the opportunity for parabolic trough collectors to succeed at least for solar field sizes from several 100 m² upwards.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:27Z
      DOI: 10.1063/5.0085792
       
  • Integrating solar heat in energy micro-grids for small scale productive
           communities

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      Authors: Manuel Pérez, José L. Torres, José D. Álvarez, Juan D. Gil, Magdalena Barnetche, Natalia Osorio, María T. Cerda
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The current efforts to implement renewable sources for community-driven solutions for energy supply in traditional population settlements having limited access to energy distribution networks are mainly based on systems devoted to fulfilling the electricity demands. However, in addition to the above, many productive activities located at those settlements could also benefit from the current advances in solar thermal energy collectors' designs aimed at providing modular and reliable heat sources for micro-industries. Accordingly, this work describes the results of a study for the integration of solar heat in five small-scale productive activities in isolated settlements from Spain, Mexico, and Chile. The study has been carried out in the framework of the MICROPROD-SOLAR project, which intends to promote and support the use of solar heat for productive processes in small-scale micro-factories, farms and other productive centers located in areas where, due to geographical, economic or environmental constraints, the access to energy is limited. The analyzed cases correspond to the following sectors: traditional beverages, milk and cheese processing and greenhouse heating. They were selected as a first reference for a techno-economic assessment to support stakeholders and end-users' specific initiatives. Simulations with a specific tool have been carried out to evaluate both the reachable solar fraction and the payback period, in each of the case studies showing favorable results in almost all the cases for the possible integration of a solar heat system.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:27Z
      DOI: 10.1063/5.0086727
       
  • Investigation of MgCl2/graphite foam thermal energy storage system with
           internally supported plate-fin flow channels

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      Authors: Wenhua Yu, Dileep Singh, David M. France, Saroj Bhatta, Jim Nash
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      An innovative thermal energy storage system that combines the advantages of the phase-change material/graphite foam latent-heat thermal energy storage medium and the internally supported plate-fin cell architecture heat transfer fluid flow channel was developed. In this study, experimental investigations were conducted on the test module designed and optimized based the full-scale thermal energy storage system. Specifically, the performance of the thermal energy storage system was measured for charging and discharging behaviors through experimental testing, the effect of thermal cycling was determined through repeated charging and discharging testing, the influence of the interface between the phase-change material/graphite foam composite and the surface of the heat transfer fluid flow channels resulting from any gaps and/or degradation was investigated, and the experimental data was compared to the numerical simulation results. The experimental data was found to be in reasonable agreement with the numerical simulation results.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:27Z
      DOI: 10.1063/5.0085671
       
  • Annual performance assessment of a 50 MWe commercial solar tower plant
           with improved open volumetric receiver

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      Authors: Peter Schwarzbözl, Stefano Giuliano, Kareem Noureldin, Till Doerbeck, Aina Rosselló, Johannes Schrüfer
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Central receiver systems with open volumetric air receiver and packed bed thermal storage are an alternative to the currently deployed salt and steam receiver plants. The air receiver technology is being tested as a complete system at the 1 MWe test and demonstration plant Solar Tower Jülich since 2009 and shows high robustness and availability. Recent developments focused on increasing the thermal receiver efficiency. Changing the receiver geometry to a cavity type and further structural improvements resulted in an efficiency increase to above 85%, as experiments and CFD simulation models show. The high dynamic flexibility could be further enhanced. A commercial reference plant with 50 MWe power level was defined for a potential location in South Africa. An LCOE analysis based on an annual performance simulation was conducted for several design and operational alternatives. Under good conditions, results show LCOE values below 90 €/MWh for the single 50 MWe standard unit. Higher power levels can be reached by multiplying such standard units, leading to further cost savings.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:26Z
      DOI: 10.1063/5.0085758
       
  • Solar extractive metallurgy for the production of Mg and Zn from
           carbothermal reduction of MgO and ZnO at low pressure in a solar
           thermochemical reactor

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      Authors: Srirat Chuayboon, Stéphane Abanades
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Solar thermochemical pyro-metallurgical process is an attractive prospect for the sustainable conversion of both metal oxides and sunlight into value-added chemicals. In this work, a comparative study of carbothermal reduction of ZnO and MgO was performed in a 1.5 kWth directly-irradiated solar reactor utilizing concentrated sunlight. Important operating parameters were studied during the experiments including the type of carbon reducing agent (activated charcoal and carbon black) in batch and continuous operating modes under both reduced (0.11-0.40 bar) and atmospheric (0.90 bar) pressures in the operating temperature range of 600-1600°C, demonstrating the solar reactor flexibility, reliability, and robustness. As a result, regarding batch tests, a decrease in the total pressure promoted the conversion of ZnO and MgO above 78% and 99%, respectively, which in turn increased Zn and Mg yields. Nevertheless, an increase in the CO2 with decreasing total pressure was observed, especially in the case of ZnO reduction, due to reduced gas residence time. In contrast, CO2 yield remained negligible in the case of MgO. Regarding continuous tests, an increase of gas production yields as well as reaction extent through the increase of reactant feeding rate was highlighted. Employing activated charcoal showed higher conversion of both ZnO and MgO, resulting from the higher available specific surface area for chemical reactions. Finally, high-purity Zn and Mg content in the solar-produced powders were achieved.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:26Z
      DOI: 10.1063/5.0085638
       
  • Techno-economic analysis of solar thermochemical fuel production:
           Sensitivity and uncertainty

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      Authors: Christoph Falter, Andreas Sizmann
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The techno-economic performance of the solar thermochemical pathway is analyzed with a specific focus on sensitivity and uncertainty of the production costs of jet fuel. A baseline plant design located in Albuquerque, NM, USA, is chosen, due to the favorable direct normal irradiation of 2700 kWh/(m2 y). This irradiation level enables a relatively small size of the solar concentrator, which reduces the investment costs. At a thermochemical energy conversion efficiency of 19% and specific costs of the heliostats of 50 €/m2 and of carbon dioxide air capture of 100 €/t, the fuel production costs are 1.34 €real/L jet fuel. In a sensitivity study, the most influential parameters are found to be the weighted average cost of capital, the heliostat field cost, the cost of CO2 air capture, and the solar irradiation at the plant location. Five parameters are further varied in an uncertainty analysis according to assumed input probability density functions. The resulting production cost distribution has a 90% confidence interval of 1.09-1.47 €real/L with a mean value of 1.27 €real/L.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:26Z
      DOI: 10.1063/5.0085637
       
  • Steady state criteria for parabolic trough receiver heat loss measurements

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      Authors: Johannes Pernpeintner, Björn Schiricke
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Heat loss of parabolic trough receivers is measured in the laboratory at Steady State. Criteria for the Steady State shall ensure sufficient stabilization of the measurands without being excessive. The IEC TS 62862-3-3:2020 provides such criteria. This paper presents a model for the assessment of Steady State criteria in heat loss tests. Assuming constant heating power, lumped heat capacity and linearized heat loss, the model shows, that the IEC TS 62862-3-3 allows for significant deviations at low temperatures and large heat capacity. For the investigated configuration of low heat loss and large heat capacity, the model shows allowed deviations of 12.6 K at 100 °C, 5.5 K at 200 °C and 2.5 K at 300 °C. The paper discusses the weaknesses of Steady State criteria in the IEC TS 62862-3-3 and proposes to clarify the meaning of ±0.5 K and ±1% and, to expand the stabilization period to 60 minutes for measurements below 300 °C and to limit the scope of the standard to measurements> 240 °C.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:25Z
      DOI: 10.1063/5.0085918
       
  • Ceramic proppant dust generation in falling particle receiver applications

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      Authors: Nathan Schroeder, Clifford K. Ho
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Falling particle receivers have the potential to increase the maximum operating temperature of CSP systems by directly heating a solid particle heat transfer fluid. Particle abrasion in FPR systems can generate dust which can escape out of open receiver designs. The characterization and capture of this dust can help mitigate health risks and increase the optical and thermal efficiency of the receiver. Particle fines were generated and captured by fluidizing a bed of nominally sized particles and filtering out the entrained particulate from the air exiting the bed. Particle fine size distribution, composition, and rate of generation was found for a specific mass of fluidized particles using optical microscopy, SEM, XRD, and aerosol sampling equipment to better inform dust filtration in falling particle receiver systems.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:25Z
      DOI: 10.1063/5.0085639
       
  • Validation of a low-cost camera for Scalable HeliOstat calibRation sysTem
           (SHORT)

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      Authors: Iñigo Les, Adrian Peña-Lapuente, Marcelino Sanchez, David Olasolo, Cristobal Villasante, Raul Enrique, Jesús Fernandez-Reche
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Current commercial solar tower power plants have bet to increase the thermal storage capacity and the electrical power in order to reduce generation costs, leading to solar fields with thousands of heliostats which must be calibrated to ensure the tracking accuracy, reduce the spillage, enhance the reliability and, thus, increase the energy production. The state-of-the-art of heliostat calibration methods, the so-called camera target-method, cannot face that amount of heliostats in a reasonable time and fails when applied to distant heliostats. This work presents a calibration system based on low-cost cameras mounted on heliostats that observe artificial lights distributed around the solar field. The method can calibrate the whole heliostat field in a single night without interfering with the operation of the plant and without incurring additional costs. The calibration relies on finding the actual kinematic model of the heliostats so that the heliostat orientation is accurately characterized for whatever given heliostat angles allowing precise control over the heliostat orientation, and hence, their aim point. The method has been successfully tested at the Plataforma Solar de Almeria showing heliostat orientation accuracy below 0.5 mrad that would lead to sun tracking accuracy better than 1 mrad.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:24Z
      DOI: 10.1063/5.0085764
       
  • Influence of soiling on CSP mirrors in a mountain climate in Morroco

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      Authors: Abdelouahed Chbihi, Sofia Boukheir, Sanae Naamane, Mustapha Mouadine, My Hafid Bouhamidi
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Concentrated Solar Power (CSP) technology has known a huge evolution in the last decades. Reflector is one of the most strategic components in CSP plant and soiling is one of the most deleterious parameters that should deeply understood during the choice of the plant localization. The main aim of this analysis is to evaluate the impact of soiling on reflectors’ reflectance in a mountain climate as Morocco is launching a new CSP plant in Midelt region (Middle Atlas mountain). Through this analysis, it is shown that correlation of climate parameters like precipitations and wind is the key to enhance the understanding of the behavior of soiling in a mountain region. Up to 57% reflectance loss is recorded during summer periods while not less than 10% reflectance is registered during all periods of analysis.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:24Z
      DOI: 10.1063/5.0085640
       
  • Thermal stability of silica for application in thermal energy storage

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      Authors: Patrick Davenport, Zhiwen Ma, William Nation, Jason Schirck, Aaron Morris, Matthew Lambert
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Thermal energy storage (TES) systems have enabled concentrating solar power (CSP) to remain competitive in the modern energy mix by providing economical load shifting grid services and firming up intermittent solar resource. Free from siting constraints, TES also shows promise as an economical alternative to traditional pumped-storage hydropower (PSH) and compressed air energy storage (CAES). As potential thermal energy storage media, some solid particles demonstrate stability over wide temperature ranges which allows for increased sensible energy storage density and is essential in achieving low-cost storage. Silica sand, in the form of α-quartz, is one such candidate. This work presents a brief review of relevant silica thermophysical properties and further investigates the thermal stability of silica particles as a candidate TES media by subjecting them to two different thermal tests: (1) a 500-hour thermal treatment at 1200°C under varied atmospheres; and (2) cycling 25, 50, and 100 times between 300°C and 1200°C. For both tests, particle stability is examined by means of pre- and post-treatment Mie scattering. An additional XRD analysis is conducted for the 500-hour treatment in air. Results indicate limited changes in both particle distribution and crystallographic structure which is promising for the application as solid particle media for thermal energy storage.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:24Z
      DOI: 10.1063/5.0085641
       
  • Analysis of a chloride molten salt pump and tank interface for
           high-temperature operation

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      Authors: Derrick Charley, Kenneth M. Armijo, Hector Mendoza
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      In this investigation, heat transfer analysis of cold and hot pump-tank interfaces for a 2 MWth pilot-scale system is assessed using a developed computational fluid dynamics (CFD) model using ANSYS Fluent. A DOE Generation 3 concentrating solar power (CSP) ternary chloride molten salt mixture is used as the working fluid of each system and evaluated at different temperatures and pressures. In this CFD model work an analysis was performed for a pump assembly at the interface between the test loop and a storage tank. The model was developed for three scenarios with molten salt inlet temperatures set at 500 °C, 720 °C, and 730 °C. The real-world complex geometry was simplified and evaluated as a two- dimensional model with the purpose of estimating overall heat transfer and velocity profiles for the respective system configurations. Preliminary results indicate that pump field insulation absorbs most of the heat from radiating from the molten salt region at a max temperature of 39.48 °C and that heat transfer within the N2 ullage gas region is primarily due to natural convection and radiation.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:23Z
      DOI: 10.1063/5.0085642
       
  • Hybrid CSP-PV plants with integrated thermal storage

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      Authors: Klaus-Jürgen Riffelmann, Gerhard Weinrebe, Markus Balz
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      With the cost of solar electricity generated by photovoltaic (PV) systems dropping, the integration of PV into concentrating solar power (CSP) plants is under active consideration. PV systems are more economical in providing electricity directly to the grid during sunshine hours, whereas the main advantage of CSP plants is the availability of economical large thermal storage (TES), especially when molten salt is used as heat transfer and storage fluid. Several options to combine the strengths of the two technologies are evaluated in this paper, including: a small PV plant designed to supply the CSP plant's own consumption; hybrid CSP-PV plants where the CSP plant is mainly used to charge the storage while the PV system delivers electricity to the grid during the daytime and optionally charges the storage by means of electrical heaters (“eTES”); and finally a PV only system that provides electricity during daytime and additionally charges the thermal storage by electrical heaters. The different hybrid operation strategies are evaluated for a typical plant located in Southern Spain with mediocre direct solar irradiation. A sensitivity study on the impact of a high DNI CSP location like South Africa and an advantageous feed-in tariff at night on the plant's economics is presented.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:23Z
      DOI: 10.1063/5.0086610
       
  • RAISELIFE project extends the lifetime of functional CSP materials

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      Authors: Florian Sutter, Yaniv Binyamin, Theda Zoschke, Aránzazu Fernández-García, Sanae Naamane, Mathias Galetz, Reine Reoyo-Prats, Francisco Javier Pérez-Trujillo, Alina Aglüro, Francesco Orioli, Javier Piron, Daniel Mandler, Anne Attout, Simon Caron, Johannes Wette, Ricardo Sánchez, Angel Morales, Christina Hildebrant
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The RAISELIFE project was conducted from April 2016 until March 2020 and was funded within the H2020 program of the European Commission (Grant 686008). The project aimed at developing novel materials with extended lifetime and performance for parabolic-trough and solar tower CSP plants and thereby reducing electricity generation costs. In order to assess the expected durability of the novel materials, improved accelerated aging and qualification methods simulating in-service conditions in different climates were developed. The project brought together a broad consortium formed of industry partners, SMEs and research institutes of the CSP and material science sector. This paper summarizes the main developments and takeaways from the RAISELIFE project.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:22Z
      DOI: 10.1063/5.0085763
       
  • Vapor transport analysis of a chloride molten salt flow control valve

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      Authors: Kenneth M. Armijo, Hector Mendoza, Jeffrey Parish
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      This investigation explores thermal-fluid flow phenomena in a proportional flow control valve (FCV) within a 2 in. ID high-temperature piping transport system. The FCVs are critical components to ensure flexible nominal operation of a 2 MWth concentrating solar power (CSP) pilot-scale system in present development at Sandia National Laboratories (SNL). A computational fluid dynamics (CFD) / finite element analysis (FEA) model was developed in ANSYS that investigates multifluid phase-change transport within various sections of an FCV to explore plating and subsequent thermal-mechanical stress challenges that can exist with operations as high as 730°C. Results from the thermal-fluid model in development suggest salt vapor phase change in the N2 gas purge lines as low as approximately 476°C, which can have a negative impact on valve reliability.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:21Z
      DOI: 10.1063/5.0085644
       
  • First measurements from Mexican solarimetric network and its comparison
           with the NSRDB

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      Authors: Adriana E. González-Cabrera, David Riveros-Rosas, Teresa Martinez-Gonzalez, Mauro G. Valdés-Barrón, Héctor R. Estévez-Pérez, Roberto Bonifaz-Alfonzo
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The success of renewable energy projects depends on proper technical and financial planning. This requires the availability of accurate information on the energy resources that can be used by the electric power generation industry. In the case of solar energy in Mexico, different satellite models have been applied throughout the country. However, until a few years ago, there was no solarimetric information with sufficient precision to evaluate these models. Furthermore, variations in altitude and the great variety of climates throughout the territory complicate the measurement of any element of the climate, especially solar radiation. This work makes a comparison between solar irradiance data measured by the Mexican Solarimetric Network (RESOLMEX; Red Solarimétrica Mexicana) and the corresponding irradiance data from the National Solar Radiation Database (NSRDB). We select horizontal global irradiance for the comparison, the root mean square error (RMSE) and Bias error (MBE) were calculated. Despite the climatic differences, both datasets show a good agreement between several stations throughout an annual cycle.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:21Z
      DOI: 10.1063/5.0085645
       
  • Comparison of the representativeness of solar radiation type of days from
           the viewpoint of the production of parabolic trough and central receiver
           plants

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      Authors: Sara Moreno-Tejera, Paola Jiménez-Valero, Elena Pérez-Aparicio, Isidoro Lillo-Bravo, Manuel A. Silva-Pérez
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The classification of days according to the solar radiation features is one of the tools frequently used for the solar resource assessment, modelling or forecasting. Recent studies discuss the appropriate classification method or number of types of days, but these studies usually don't take into account, at least in an explicit way, the relation between the types of days and the yield of solar plants. In this work, we compare the representativeness of the types of days defined by two classification methods from the viewpoint of the production of a Central Receiver (CR) and a Parabolic Trough (PT) solar plant. The selected classification methods are based on the daily solar radiation features: energy, variability and temporal distribution. So, in a first step, the days of a period of 16 years of measurements recorded in Seville (Spain) are classified by these two methods. In a second step, the daily gross productions of both CSP plants are estimated using System Advisor Model program. Then, the representativeness of the types of days of each classification method is evaluated according to the production of the CR and the PT plant by means of a methodology based on the clear sky yield index or kp index. Finally, the ARE and the annual relative RMSE and the MAE for the plants and classification methods analyzed are compared. Then, we can conclude, that the representativeness of the types of days of a classification method has a certain dependence on the plant that depends on the classification method applied.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:21Z
      DOI: 10.1063/5.0085768
       
  • Committee: SolarPACES 2020 – 26th International Conference on
           Concentrating Solar Power and Chemical Energy Systems

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      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.

      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:20Z
      DOI: 10.1063/12.0010307
       
  • Introduction to a direct irradiated transparent tube particle receiver

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      Authors: Stefan Niederwestberg, Falko Schneider, Cristiano Boura, Ulf Herrmann
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      New materials often lead to innovations and advantages in technical applications. This also applies to the particle receiver proposed in this work that deploys high-temperature and scratch resistant transparent ceramics. With this receiver design, particles are heated through direct-contact concentrated solar irradiance while flowing downwards through tubular transparent ceramics from top to bottom. In this paper, the developed particle receiver as well as advantages and disadvantages are described. Investigations on the particle heat-up characteristics from solar irradiance were carried out with DEM simulations which indicate that particle temperatures can reach up to 1200 K. Additionally, a simulation model was set up for investigating the dynamic behavior. A test receiver at laboratory scale has been designed and is currently being built. In upcoming tests, the receiver test rig will be used to validate the simulation results. The design and the measurement equipment is described in this work.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:20Z
      DOI: 10.1063/5.0086735
       
  • Solar thermochemical energy storage in elemental sulphur: Design,
           development and construction of a lab-scale sulphuric acid splitting
           reactor powered by hot ceramic particles

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      Authors: Vamshi Krishna Thanda, Dennis Thomey, Lutz Mevißen, Hiroki Noguchi, Christos Agrafiotis, Martin Roeb, Christian Sattler
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      A proof of concept sulphuric acid splitting/decomposition prototype driven by hot bauxite particles is designed and developed. The lab-scale test reactor is a novel counter-current flow shell-and-tube heat exchanger with particles on the shell side and sulphuric acid on the tube side with mass flow rates of 10 kg/h and 2 kg/h, respectively. A one-dimensional heat transfer model was developed based on correlations of the flow boiling heat transfer coefficient and particle bed heat transfer coefficient for sizing the shell-and-tube heat exchanger. A detailed study was carried out in order to choose suitable materials especially in the sulphuric acid inlet and evaporation section. A new concept of an electrically heated, continuously operated particle heating system was designed and developed to provide the splitting reactor with hot particles. Different cases were studied using a finite element method (FEM) analysis to qualify the particle heater and examine its thermo-mechanical stability.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:20Z
      DOI: 10.1063/5.0085888
       
  • Theoretical and experimental studies of dual-media thermal energy storage
           with liquid metal

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      Authors: Klarissa Niedermeier, Franziska Mueller-Trefzer, Markus Daubner, Luca Marocco, Alfons Weisenburger, Thomas Wetzel
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Liquid metals have remarkable heat transport capabilities and are, thus, promising heat transfer fluids in thermal receivers in solar thermal electricity systems with high heat loads, such as central receiver systems. For thermal energy storage, a dual-media storage system with solid filler material is proposed. This configuration increases the storage capacity and decreases the storage material costs compared with a direct two-tank system. It also improves the storage performance, when comparing with a single-tank thermocline system without filler. Theoretical results show that the discharge efficiencies are highest for the largest storage heights and higher for heavy metals (lead and lead-bismuth eutectic) compared with sodium, both due to the decreased axial heat conduction and thus, minimized degradation of the thermocline. At the Karlsruhe Liquid Metal Laboratory (KALLA) at the Karlsruhe Institute of Technology (KIT) a lab-scale prototype of a dual-media storage system with filler material and lead-bismuth eutectic (LBE) as the heat transfer fluid is currently taken into operation. The first results without filler material show a good agreement between the theoretical model and the experimental results. In parallel, the compatibility of filler material candidates with LBE is investigated by storing the material in stagnant LBE for several weeks at 500°C and afterwards examining the filler material with a scanning electron microscope (SEM). The results indicate that ceramics are the most promising candidates.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:20Z
      DOI: 10.1063/5.0085881
       
  • UV degradation of primary mirrors in outdoor exposure and accelerated
           aging

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      Authors: Francisco Buendía-Martínez, Aránzazu Fernández-García, Johannes Wette, Florian Sutter, Loreto Valenzuela
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Concentrating solar thermal (CST) energy plays a fundamental role in the energetic transition which is facing our society. The energy generation of these systems hugely depends on the optical behavior of the reflectors. CST plants are installed in zones where the solar irradiance is very high. As it is well known, UV radiation is a main degradation mechanism for some materials. The possible weathering of the solar reflectors provoked by this environmental agent could be fundamental to decide the feasibility of a CST plant in a certain location. In this work, the degradation provoked by UV radiation in a series of different silvered-glass solar reflectors was deeply studied. For that purpose, seven reflector types were exposed for three years in countries of high interest for CST plants such as Chile, Spain and Morocco. An UV aging test based on fluorescent lamps was carried out to reproduce the degradation mechanism observed outdoor. Finally, the acceleration factors between the outdoor sites and the UV test were obtained.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:19Z
      DOI: 10.1063/5.0091462
       
  • Photogrammetry analysis of a vacuum-membrane solar dish using elliptical
           television antennas

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      Authors: Jonathan K. Swanepoel, Casey Roosendaal, Willem G. le Roux
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The design of a solar dish usually involves the complex trade-off between cost and optical quality. The use of off-the-shelf elliptical television antennas in a vacuum-membrane solar dish array is investigated in this paper, in an effort to reduce the cost of solar concentration. Each facet comprised a 50-µm-thick Mylar sheet membrane, stretched and sealed over the elliptical rim of an off-the-shelf satellite television antenna, forming a narrow cavity in which a vacuum could be drawn to pull the Mylar sheet into a concave shape. The shape of the facet concavity was investigated using photogrammetry. An elliptic paraboloid and a hemi-ellipsoid were fitted to the photogrammetry results, and it was determined that both fits could be used to represent the concave shape. The investigation allowed for the concave shape to be modelled in a ray tracing analysis, where the flux map was compared with the result from a lunar flux mapping analysis. Comparison of the intercept factor trends showed that further investigation into quantifying the contributions of individual facet alignment errors should be performed to further improve the model. With improvements in individual facet alignment, the use of off-the-shelf elliptical television antennas in a vacuum-membrane solar dish array can be a viable solution to reduce the cost of solar concentration.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:19Z
      DOI: 10.1063/5.0087025
       
  • Mayenite-supported CaO for thermochemical storage applications: Ageing
           time effect over conversion

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      Authors: Michela Lanchi, Annarita Spadoni, Salvatore Sau, Anna Chiara Tizzoni, Francesca Varsano, Natale Corsaro, Luca Turchetti, Raffaele Liberatore, Anna De Girolamo Del Mauro, Tiziano Delise, Emiliana Mansi, Maria Anna Murmura, Maria Cristina Annesini
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Thermo Chemical Storage systems (TCS) are gaining an increasing interest in the field of long term-thermal energy storage, thanks to their potential applicability in the Concentrated Solar Power technology to increase the electricity generation flexibility, and in different energy sectors operating at medium/high temperature levels, including the industrial one, to optimize the heat recovery and accumulation. As for the high temperature (HT) applications, research is currently focused on oxides and hydroxides-based as well as carbonates-based ones. The latter have been mainly proposed in the literature as CaO/CaCO3 system, initially applied to CO2 capture technologies. However, in order to overcome the intrinsic ciclability limitation observed for natural dolomite and limestone, synthetic sorbents have been recently developed, like the calcium oxide supported on Mayenite (Ca12Al14O33), which has also been investigated by ENEA, showing a significant durability. Despite a fast reaction kinetics and a high conversion extent (up to 80-90% in long isothermal conditions), both in carbonation and calcination steps, this material has shown interaction with air moisture and ambient CO2, affecting the reproducibility of the tests. The objective of the present work is to assess the ambient air stability of the CaO/Mayenite system, to verify the need of pre-treatment processes. At this purpose, CaO/Mayenite powder was synthesized, morphologically characterized and tested thermogravimetrically at different ageing level, namely 30 days and 60 day. The experimental campaign confirms that carbonation conversion remarkably enhances after 30 days of ambient air exposure, while it remains unvaried for further ageing times as a consequence of material properties stabilization. This result indicates that an initial air exposure of about 1 month is sufficient to guarantee a substantial reproducibility of the material performances and no energy consuming pre-treatments are required to stabilize the material response.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:19Z
      DOI: 10.1063/5.0085760
       
  • Influence of solar heat sources on packed bed TES performances

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      Authors: Aubin Touzo, Regis Olives, Guilhem Dejean, Doan Pham Minh, Mouna El Hafi, Xavier Py
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The influence of solar constraints is investigated on the Eco-Stock®, a commercial packed bed developed by the company Eco-Tech Ceram (1.9 MWhth at 525°C). The first test takes into account the simulated solar power variation along the day. Power variation has a minor impact on the packed bed performance, with a 3% decrease on the yield at 0.8 of cutoff temperature. Numerical results match the experiment, proving the model to handle properly power variation. The second test takes into account intermittencies, due to potential clouds. The stand-by phases had a major impact, reducing the yield by 13% at 0.8 of cutoff temperature, due to heat losses and both axial and radial stratification.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:19Z
      DOI: 10.1063/5.0093521
       
  • Computational fluid dynamic investigations on a small-scale liquid sodium
           loop

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      Authors: Joachim Fuchs, Frederik Arbeiter, Michael Böttcher, Wolfgang Hering, Heiko Neuberger, Robert Stieglitz
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Liquid metal heat transfer systems are a technically attractive option to increase the efficiency of CSP plants. Sodium as heat transfer medium is promising especially due to high heat transfer rates. In this paper, basic considerations are made to match the requirements of a small-scale loop with sodium as heat transfer medium. The setup of the test facility KArlsruhe ReceIver test FAcility (KARIFA) to heat up this loop with a 20 kW IR laser is described. The loop is planned as an integrated design using an additive manufacturing process. Different technologies like selective laser melting (SLM) are established processes to realize an integrated design and to bring together components in one part. Some variations must be implemented to adapt these processes to liquid metal loops. The high heat fluxes also demand a flow simulation to ensure an efficient and safe operation. A Reynolds-averaged Navier-Stokes (RANS) steady state simulation was performed to show the surface and duct temperatures as well as dimensionless values to analyse the characteristics of the sodium flow.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:18Z
      DOI: 10.1063/5.0086617
       
  • High-temperature thermal properties of particles in consideration for
           thermal storage in concentrated solar power systems

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      Authors: Jeff Maskalunas, Greg Nellis, Mark Anderson
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Particles, specifically sands, may be an alternative pathway for Thermal Energy Storage (TES) in high-temperature Concentrated Solar Power (CSP) in place of using solar salts. As seen in testing for this research, these particles have greater thermal stability at higher temperatures than solar salts while still being relatively inexpensive. This work explores the high-temperature static thermal properties, such as bulk conductivity and heat capacity, of various particles. Future work will use these properties to study the dynamic characteristics of sand including the heat transfer coefficients for high-temperature, packed-bed particle flow. To this end, this paper also describes an experimental facility that is being fabricated in order to accomplish these flowing particles tests.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:18Z
      DOI: 10.1063/5.0085803
       
  • Transient thermal performance of high-temperature particle storage bins

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      Authors: Kaden Plewe, Jeremy N. Sment, Mario J. Martinez, Clifford K. Ho, Dongmei Chen
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The design, modeling, and integration of high-temperature particle storage bins is a critical component of Gen. 3 concentrated solar power (CSP). Particle storage bins control the temperature and flow rates throughout the particle circulatory system, so having a fundamental understanding of their transient thermal behavior is highly advantageous for the design and multi-level control of future CSP systems. This paper provides contributions to this understanding by presenting a semi-analytic method for modeling the transient thermal behavior of bulk particle bins. The model is verified with experiments and a baseline CFD model and then used to make conclusions about the dominant heat transfer modes in bulk particle bins and the general transient thermal performance of related systems.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:18Z
      DOI: 10.1063/5.0085649
       
  • Design of a novel CSP/MED desalination system

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      Authors: Christopher Sansom, Kumar Patchigolla, Kranthi Jonnalagadda, Peter King
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      We describe the design of a large-scale thermal desalination demonstrator unit for use in arid locations with a medium-to-high DNI. Most of thermal energy is provided by a conventional parabolic trough field, in the case of the demonstrator this being 4MWt. The desalination sub-system comprises a 3-effect MED, the first stage of which is a large 20 m diameter glass and steel-structured geodesic and transparent dome. The thermal energy is supplemented by direct sunlight transmitted through the dome and by an arc of small heliostats which focus yet more sunlight onto the dome itself. The prototype is under construction at Neom in KSA.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:17Z
      DOI: 10.1063/5.0085769
       
  • Implementation of the heliosat 2 model in Mexico from GOES 13
           satellités images

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      Authors: David Riveros-Rosas, María. E Sánchez-Diaz, Víctor M. Velasco-Herrera, Adriana E. González-Cabrera, Mauro Valdés-Barrón, Luis F. Zarzalejo
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The use of satellite images for local evaluation of the solar resource represents a more accurate method than interpolation of surface data measured in broad regions (Rigollier et al. 2004). This work presents the first results of the implementation and adequacy of the Heliosat 2 model, for use with images of the GOES13 satellite (Rigollier et al. 2004) (Albarelo et al. 2015) for the case of Mexico. With the model, the results of daily radiation averages monthly were obtained for a full annual cycle. The results also show an average annual relative error, between modeled and measured data, acceptable and comparable with previous works in other regions in the world.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:17Z
      DOI: 10.1063/5.0085648
       
  • Performance of alloy 600 in flowing commercial Cl salt at
           600°-750°C

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      Authors: Bruce A. Pint, J. Matthew Kurley, Dino Sulejmanovic
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      For the next generation of concentrating solar power (CSP) plants, K-Mg-Na chloride salts are being explored as a potential higher temperature thermal storage medium. However, there are concerns about compatibility of structural alloys with the salt. To move beyond simple static pot compatibility experiments while a pumped salt loop is being constructed, thermal convection loops were constructed from ∼16wt.%Cr Ni-based alloy 600 and operated for 100-1000 h with peak temperatures of 700° and 750°C. These experiments indicated that alloy 600 was compatible up to 700°C with purified (i.e. low O2-) or dried (low H2O) industrial-sourced Mg-K-Na chloride salt with
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:16Z
      DOI: 10.1063/5.0085929
       
  • Renewable thermal hybridization framework for industrial process heat
           applications

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      Authors: Sertaç Akar, Parthiv Kurup, Josh McTigue, Matt Boyd
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Solar industrial process heat (SIPH) technologies, such as concentrating solar power collectors, could economically replace the steam or heat needs at many industrial sites by providing high-temperature heat transfer fluids (HTFs) such as pressurized water, synthetic-oil, or direct steam. Renewable thermal energy systems (RTES) could be hybridized with different renewable options e.g., flat plate collectors with parabolic trough collectors, or combined with existing heat supplies (e.g., fossil fuels), to give options for targeted SIPH applications, industrial decarbonization and the reduction of fuel consumption. Hybrid solutions and thermal energy storage will be important for the dispatch of heat at optimal times needed by the demand side of the buildings and industrial applications. At present, there is no integrated modeling tool for hybrid RTES, and this paper highlights the development of a renewable thermal hybridization framework for IPH use that is built from existing tools like System Advisor Model. The long-term vision for the framework (through significant further research) is to develop a coupled hybrid energy generation and cost analysis tool, where the tool could help the user in determining the most suitable and cost-effective technologies for their applications. Ongoing work will look to add costs for RTES options and further refinement on the selection of suitable technologies. This future tool could calculate the levelized cost of heat of various RTES hybrid options, by taking the user's solar resource, fuel costs, industrial heat demand profile, available land, and other factors into account to determine the applicability into their process.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:16Z
      DOI: 10.1063/5.0085805
       
  • DNI day-ahead forecasting with confidence factor

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      Authors: Zeyad Yasser, Daniel Angulo, Mark Schmitz, Marion Schroedter-Homscheidt
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      TSK Flagsol Engineering GmbH through a cooperation with the DLR (the German Aerospace Center) and sponsored by the German Federal Ministry of Economics and Technology (BMWi) has developed a DNI day-ahead forecasting algorithm with a confidence factor for the operation of CSP power plants. This algorithm is integrated into the weather and energy production forecasting system CSP-FoSyS. CSP-FoSyS is both a meteorological and an electrical and thermal power forecast system based on satellite data, numerical weather prediction model and cloud cameras.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:16Z
      DOI: 10.1063/5.0086345
       
  • Status update of the SolarPACES heliostat testing activities

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      Authors: Marc Röger, Kristina Blume, Tim Schlichting, Mike Collins
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Power tower or central receiver systems use hundreds to ten thousands of two-axis tracking mirrors, so called heliostats, which reflect and focus the sunlight onto a receiver on top of a tower during the day. As basis for a well performing heliostat field, a single heliostat has to perform “correctly”. In order to describe and measure the performance of a single heliostat, the SolarPACES Guideline for Heliostat Performance Testing has been developed by a group of R&D and industry experts during the last years. However, at the end, the performance of the whole field, which means the superposition and interaction of all heliostats determines the energy collected in the aperture of a solar central receiver. For that reason, a second guideline is currently outlined, the SolarPACES Guideline for Heliostat Field Performance Testing. Both guidelines aim to be commonly agreed protocols between R&D centers and industry in the field of heliostat performance testing. Recently, a third guideline activity has been started to improve and unify heliostat wind load design methods. The once finalized guidelines (or their concepts) should be included in international standards (e.g. IEC) and used by national organizations like DKE, AENOR, ASME, ASTM. This paper gives an update of the state of the three guidelines being developed in the SolarPACES task III-heliostat working group.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:15Z
      DOI: 10.1063/5.0087037
       
  • Basic engineering of a high performance molten salt tower receiver system

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      Authors: Cathy Frantz, Matthias Binder, Konrad Busch, Miriam Ebert, Andreas Heinrich, Nadine Kaczmarkiewicz, Bärbel Schlögl-Knothe, Tobias Kunze, Christian Schuhbauer, Markus Stetka, Christian Schwager, Michael Spiegel, Cristiano Teixeira Boura, Thomas Bauer, Alexander Bonk, Stefan Eisen, Bernhard Funck
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The production of dispatchable renewable energy will be one of the most important key factors of the future energy supply. Concentrated solar power (CSP) plants operated with molten salt as heat transfer and storage media are one opportunity to meet this challenge. Due to the high concentration factor of the solar tower technology the maximum process temperature can be further increased which ultimately decreases the levelized costs of electricity of the technology (LCOE). The development of an improved tubular molten salt receiver for the next generation of molten salt solar tower plants is the aim of this work. The receiver is designed for a receiver outlet temperature up to 600 °C. Together with a complete molten salt system, the receiver will be integrated into the Multi-Focus-Tower (MFT) in Jülich (Germany). The paper describes the basic engineering of the receiver, the molten salt tower system and a laboratory corrosion setup.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:14Z
      DOI: 10.1063/5.0085895
       
  • Blossaim, a deterministic aiming strategy for circular aperture receivers

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      Authors: Derwalt J. Erasmus, Alberto Sánchez-González, Theodor W. von Backström
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Small heliostats tend to produce a sharp peak flux on a receiver aperture if they are all aimed at a single point. Several receiver concepts have circular receiver apertures and polar heliostat fields. It is of interest to flatten the flux distribution on such receivers to achieve a more homogeneous receiver surface temperature for improved thermal absorption and reduced thermal stress. A new implementation of an existing aiming strategy methodology is presented in this paper for a circular receiver with a polar heliostat field. This implementation is investigated using a convolution- projection flux modelling approach and compared with a baseline of single point aiming. The aiming strategy implementation reduces the peak flux magnitude from single point aiming by 66% and leads to a substantially uniform flux distribution on the aperture while incurring a 17.1% lower field optical efficiency on an aperture with a diameter of 1 m. The optical efficiency cost can be improved to a reduction (from single point aiming) of only 2% by slightly extending the aperture diameter for the same aiming points. The implementation deterministically arranges the aiming points of the heliostats to produce a flux distribution that is robust to a changing field optical efficiency distribution with solar time.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:14Z
      DOI: 10.1063/5.0085654
       
  • Thermomechanical modeling of counter-flow packed-bed particle-to-sCO2 heat
           exchangers

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      Authors: Nicolas A. DeLovato, Kevin Albrecht, Clifford Ho
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      An area of high interest for the next generation of concentrating solar power is the coupling of high temperature particle receivers with high efficiency supercritical carbon dioxide (sCO2) power cycles. This integration relies heavily on the realization of a particle-to-sCO2 heat exchanger design that can meet performance and cost targets. This work presents the thermomechanical modeling of a 1 MWt counter-flow particle-to-sCO2 heat exchanger via finite element analysis. Particle flow, temperature profiles, and stress profiles are all solved for by the model and used to determine several major performance metrics for the heat exchanger. These predictions include the thermal performance, sizing, and start-up procedure of a counter-flow heat exchanger design for its use in the Generation 3 Particle Pilot Plant for concentrating solar power. The model predicts an overall heat transfer coefficient of 434.47 W/m2-K for the heat exchanger design investigated here, a sizable improvement over previous designs [1]. The model also determined the optimal start-up procedure constant ramp up of the particle inlet temperature which induced less stress within the heat exchanger than a ramp of the particle flow rate. Several key factors on the performance of the heat exchanger were found during this modeling and are discussed.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:13Z
      DOI: 10.1063/5.0089334
       
  • Novel solar tracking system for large spherical concentrators

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      Authors: Cristobal Villasante, David Olasolo, Saioa Herrero, Iñigo Pagola, Adrian Peña, Gorka Kortaberria, Eneko Gomez-Acedo, Ana Bernardos
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Spherical concentrators can have significant economic advantages over parabolic concentrators. Much of its economic interest is based on the possibility of using fixed solar fields and therefore using relatively cheap conventional construction methods to support the mirrors that comprise the reflective surface. They are also known as SRTA (Stationary Reflector/Tracking Absorber) systems. By contrast, it is necessary to move the receiver in a wide range of positions. This presents a challenge and places high demands not only on the tracking system itself but also on the supporting structure of the receiver. This becomes increasingly critical the larger the concentrator is. This article presents refers to a new modular plant configuration and in particular, it presents, a novel solar tracking system aided by a large-scale measuring approach that limits these drawbacks and could be efficiently implemented in large SRTA systems. The novelty of the concept lies both in the configuration of the solar plant and in the tracking and measurement solutions implemented, which are described in detail in this article.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:13Z
      DOI: 10.1063/5.0085897
       
  • Design & demonstration of a 10-meter metallic reflector-based Fresnel
           lens, with lower focal point fixed to the ground

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      Authors: Ayman Al-Maaitah
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The innovative Fresnel-based reflective solar concentrator with a fixed focal point to the ground is presented in this work. The conceptual design of the tracking system allowing for the fixed focal point and the reflector rings design is explained to achieve the main advantage of this ring-array concentrator. The concept of no-shading, no blocking, no escaping, and even distribution of solar flux at the focal area is explained. A real system of 10 m in diameter is designed, simulated, constructed, and tested. Based on the simulation an intercept factor of 91% is achieved based on the aperture area. The concentration and simulated flux at the focal area are shown. Preliminary testing of the real prototype shows satisfactory agreement between simulation from one side and real performance from the other side. The fixed focal area with respect to the ground is proven at the same location as the design within limits of 10 mm. The focal area diameter measured is close to that of the simulation within 15mm limits. The flux distribution shape in real testing qualitatively reflects that of the simulation. Finally, high temperatures over 1000°C were reached at the focal area within 2 minutes of concentrating the solar radiation on the focal area.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:13Z
      DOI: 10.1063/5.0085658
       
  • FluxSPT: Tool for heliostat field aiming and flux mapping in solar power
           tower plants

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      Authors: Alberto Sánchez-González, María Reyes Rodríguez-Sánchez, Domingo Santana
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      FluxSPT is a software tool for the characterization of heliostat fields. A GUI-based version of this tool is available for free download, which requires the installation of Matlab Runtime, freely available too. FluxSPT generates the flux maps on central receivers from a heliostat field, considering its optical losses. The optical model is based on the convolution-projection method, previously validated by the authors. Symmetric flux distributions respect to the receiver midplane are computed using either the single or the multi-aiming strategy. For the multiaiming strategy, a single parameter (k aiming factor) is utilized to spread aimpoints and control the allowed peak flux and spillage.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:13Z
      DOI: 10.1063/5.0085656
       
  • A two-stage method for measuring the heliostat offset

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      Authors: Wilko Jessen, Marc Röger, Christoph Prahl, Robert Pitz-Paal
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The conventional method of initial heliostat calibration by sequentially pointing the heliostats one by one onto a target is a very slow process. The use of unmanned airborne vehicles (UAVs) is a possible approach to developing a less time consuming procedure for the initial setup of the field control system and elimination of offset in light beam pointing. This paper presents a UAV based method for measuring the heliostat offset in two stages. The first stage, preliminary and less accurate, creates a three-dimensional model of the mirror facet corners in order to estimate the heliostat orientation. The estimated orientation from the first stage is a prerequisite for the second stage of measurement, in which the highly accurate heliostat orientation is derived from deflectometrically measuring the mirror shape. While work is still ongoing to fully implement the final steps of the second stage, the measuring principles has been demonstrated and partially validated for the first stage.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:12Z
      DOI: 10.1063/5.0087036
       
  • Comparison of advanced parameter identification methods for linear Fresnel
           collectors in application to measurement data

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      Authors: Peter Schöttl, Alaric C. Montenon, Costas Papanicolas, Stephen Perry, Anna Heimsath
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Modeling of the Linear Fresnel collectors in a real environment using standardized, state-of-the-art approaches is still inaccurate, yet it is crucial for robust loop control and collector yield assessment. Two advanced parameter identification methodologies – ParaID by Fraunhofer ISE and RealTrackEff by the Cyprus Institute – are compared in terms of the underlying equations, which extend ISO 9806. Both approaches are then applied to a Linear Fresnel collector research facility at the Cyprus Institute, for which a database of more than 50 measurement days is available, including reflectometric measurements. For both methods, several variations with increasing complexity are tested and the quality of the resulting fit in terms of outlet temperature is studied. Both methods take into account soiling/cleanliness and non- linear collector behavior. While ParaID focuses on the identification of the IAMs in a real environment, the method by the Cyprus Institute links the efficiency to non-linear tracking effects. Real collector characteristics like varying cleanliness and asymmetric collector behavior are found to have a strong impact on the collector performance and the identified parameters. For the ParaID approach, additional results regarding confidence intervals based on Bootstrapping and regarding identified Incidence Angle Modifiers are presented.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:12Z
      DOI: 10.1063/5.0085892
       
  • Dynamic thermal analysis of an external cylindrical receiver in an
           object-oriented modelling paradigm

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      Authors: Giovanni Picotti, Michael E. Cholette, Francesco Casella, Marco Binotti, Theodore A. Steinberg, Giampaolo Manzolini
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The components exposed to the highest temperature and heat fluxes in Solar Tower plants are the tubes of the panels composing the central receiver. Their structural integrity is weakened due to fatigue and creep phenomena, likely worsened by a corrosive environment, and their solar power harvesting performance suffers from diminished absorptance of their coating. This paper describes a 2D dynamic thermal model of the tubes of a central receiver, developed following an Object-Oriented modelling paradigm, and applies the model to assess the impact of degradation phenomena such as corrosion, coating deterioration, and soiling of heliostats. The model is verified against steady-state data available in literature both on overall receiver metal maximum temperature, HTF outlet temperature and absorbed heat, and on detailed circumferential analysis of the metal external temperature for a specific tube. The dynamic behavior of the receiver is also assessed, with focus on the impact of cloud events and the induced thermal transients.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:12Z
      DOI: 10.1063/5.0085650
       
  • MOSAIC: The first prototype of a semi-Fresnel spherical concentrator

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      Authors: Iñigo Pagola, Adrián Peña-Lapuente, Marcelino Sánchez, Ana Bernardos, Cristóbal Villasante, Emilio Puche, David Ramírez, Josep Ubach
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The MOSAIC concept is based on a fixed concentrator and a moving receiver which significantly reduce the moving parts and therefore the cost. The whole concept is based on the optics of spherical mirrors. A spherical mirror reflects the rays along a focal line which is determined by the center of the sphere and the sun position. Some Concentrated Solar Power (CSP) systems based on this concept have been proposed in the literature and there are some experiences of pilot plants. All the previous prototypes are based on a solar bowl of a single curvature radius. However, MOSAIC is the first concept that is based on a semi-Fresnel concentrator with several radii of curvature. As part of the MOSAIC Horizon 2020 project, a prototype of fixed semi-Fresnel concentrator and moving receiver with a novel tracking system has been designed and is being built in Spain. This semi-Fresnel approach is the result of the techno- economic optimization to maximize the collection of solar energy while reducing the construction and installation cost. This article gathers the development of the solar field for the new concept of the solar field, the challenges found during the design phase and how all this information is used to erect a real scale prototype.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:11Z
      DOI: 10.1063/5.0085891
       
  • Design of a heliostat field and liquid sodium cylindrical receiver for the
           Gen3 liquids pathway

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      Authors: Charles-Alexis Asselineau, William Logie, John Pye, Felix Venn, Shuang Wang, Joe Coventry
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      This study describes the design of a surround heliostat field and liquid sodium cylindrical receiver operating between 520 °C and 740 °C, compatible with the DOE Gen3 liquid pathway. The design methodology is detailed including the determination of the field layout and receiver dimension, aiming strategy and associated thermomechanical stress limitations using a combination of ray-tracing, an energy, mass and momentum balance based on finite differences, and a finite-element thermo-elastic stress model. Overall, it is found that a CSP system based on a liquid sodium cylindrical receiver can provide an annual field and receiver efficiency of 44.9% while operating safely with regards to flux limitations at temperatures compatible with a high-efficiency supercritical CO2 cycle. These findings, focused on receiver-field interaction, will be useful for the upcoming design of a full system with optimized LCOE.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:11Z
      DOI: 10.1063/5.0085740
       
  • Operation optimization of an array of receiver-reactors for solar fuel
           production

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      Authors: Johannes Grobbel, Martin Fabian Sollich, Daniel Maldonado Quinto, Alon Lidor, Christian Sattler
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      In many concepts for the solar thermochemical production of fuels in a large scale, it is planned to place an array of receiver-reactors on a single solar tower. We investigate how each of these reactors needs to be operated and how the available power of the heliostat field should be distributed to the respective receiver-reactors to obtain maximum amount of solar fuel. Therefore, we developed a model for a single receiver-reactor, which is then used to analyze the single reactor operation. Based on that we present a heuristic which tries to maximize the hydrogen produced by an array of receiver-reactors for a given solar power. As our results are preliminary, we give an outlook on ongoing and future work in the end.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:11Z
      DOI: 10.1063/5.0085738
       
  • Comparison of promising materials for filling thermocline tanks as thermal
           energy storage of a CSP plant applying air as HTF

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      Authors: Francisco Cabello Nuñez, Fritz Zaversky
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      This work focuses on the comparison between different filler materials which can be used in the thermal storage system of an air CSP plant. In order to carry out this analysis, a packed-bed model of filler material has been developed, this model has been successfully validated against experimental data provided by external bibliography. Then, this model has been used to size the storage system for the different filler materials stated in this study. An iterative process has been carried out, varying the size of the storage system until the discharge time of the storage when the convergence solution has been reached is equal to the 11 hours of storage required by the plant. Once the storage system has been sized for the different filler materials, an estimation of the cost for each solution has been done. The results suggest than the steel-making slag is the filler material which leads to the cheapest thermal storage system.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:11Z
      DOI: 10.1063/5.0085736
       
  • Deep decarbonization of the European power sector calls for dispatchable
           CSP

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      Authors: Gustav Resch, Franziska Schöniger, Christoph Kleinschmitt, Katja Franke, Richard Thonig, Johan Lilliestam
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Concentrating Solar Power (CSP) offers flexible and decarbonized power generation and is one of the few dispatchable renewable technologies able to generate renewable electricity on demand. Today (2018) CSP contributes only 5TWh to the European power generation, but it has the potential to become one of the key pillars for European decarbonization pathways. In this paper we investigate how factors and pivotal policy decisions leading to different futures and associated CSP deployment in Europe in the years up to 2050. In a second step we characterize the scenarios with their associated system cost and the costs of support policies. We show that the role of CSP in Europe critically depends on political developments and the success or failure of policies outside renewable power. In particular, the uptake of CSP depends on the overall decarbonization ambition, the degree of cross border trade of renewable electricity and is enabled by the presence of strong grid interconnection between Southern and Norther European Member States as well as by future electricity demand growth. The presence of other baseload technologies, prominently nuclear power in France, reduce the role and need for CSP. Assuming favorable technological development, we find a strong role for CSP in Europe in all modeled scenarios: contributing between 100TWh to 300TWh of electricity to a future European power system. This would require increasing the current European CSP fleet by a factor of 20 to 60 in the next 30 years. To achieve this financial support between € 0.4-2 billion per year into CSP would be needed, representing only a small share of overall support needs for power-system transformation. Cooperation of Member States could further help to reduce this cost.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:10Z
      DOI: 10.1063/5.0086710
       
  • Dry cooler contribution to LCOE in a sCO2 power cycle for CSP

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      Authors: Kelsi Katcher, Abhay Patil
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      In order to maintain viability as a future power-generating technology, concentrating solar power (CSP) must reduce its levelized cost of electricity (LCOE). One component of solving this problem is reducing the cost of the power block while simultaneously increasing the efficiency of the thermodynamic cycle. One disruptive technology that has the promise to accomplish this is supercritical CO2 (sCO2) based power cycles. These cycles are conceptually similar to steam cycles; however, they have substantially smaller turbomachinery at equivalent power while also delivering more efficiency at turbine inlet temperatures of 500-700°C.Previous work has thoroughly investigated the sCO2 turbomachinery design and its impact on power cycle performance and LCOE. However, the precooler (upstream of the first stage compressor) has received significantly less attention. The pr-cooler design is not trivial because minimizing the compressor inlet temperature and temperature variation are critical to cycle performance. Compressor performance and cycle efficiency vary significantly with low-side temperature. Also, operating with a compressor inlet temperature away from the design point (above or below) significantly degrades cycle efficiency. Because CSP plants are generally planned for installation in remote, arid areas where water is scarce, dry cooling is required. The current state-of-the-art dry cooling technology consist of large bays of finned tubes, cooled by fan-driven air in cross flow. The fan-driven air allows for low power consumption and low operating cost. However, the cross-flow configuration results in low thermal effectiveness and maldistribution of air throughout the tube banks. This requires the interface area between streams to be very large, meaning very large installations incurring large capital cost. It has been found that improvements to the dry cooler technology can further reduce the power block contribution to LCOE.This study investigated the impact of the precooler on the LCOE for a CSP facility utilizing a sCO2 recompression Brayton cycle. This paper presents the high-level sensitivity studies used to determine the best path forward for reducing the precooler’s contribution to LCOE. The sensitivity study included investigation of the cooler performance (approach temperature), CO2-side pressure drop, air-side pressure drop, air-supply power consumption, and cooler system capital cost. Results of the study show that utilizing a dry cooler with a high effectiveness (achieved at higher heat exchanger capital cost) and low air-side power consumption levels produced the lowest LCOE contribution. Applying more advanced heat exchanger technologies will be required to reach the higher heat transfer effectiveness values, while maintaining reasonable capital cost values.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:10Z
      DOI: 10.1063/5.0086039
       
  • Start-up time and thermal losses of a particle solar receiver under
           transient operating conditions

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      Authors: Muhammad Mujahid Rafique
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      A refractory-lined particle receiver has been analyzed during its start-up under transient operating conditions. The influence of solar resource variability on the start-up time and overall thermal losses associated with particle receivers has been investigated using real-time minutely variability of solar resource on a clear sky and cloudy day. New insight is provided on the role of the refractory lining thickness on receiver's start-up time and thermal losses.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:10Z
      DOI: 10.1063/5.0086798
       
  • Lifecycle estimation for different solar central receiver configurations

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      Authors: Marta Laporte-Azcué, Pedro Ángel González-Gómez, María de los Reyes Rodríguez-Sánchez, Domingo Santana
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The receiver of the Solar Power Tower plants is one of the subsystems under the most highly demanding working conditions. In this study, the lifetime of various external tubular receiver configurations, also under different heat flux distributions, are obtained in order to test how they respond under both design and external variations, aiming to set certain guidelines that may aid the central receiver selection. To achieve it, an analytical approach is followed, which allows to obtain the estimated operation days in terms of the creep and fatigue damage.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:10Z
      DOI: 10.1063/5.0085742
       
  • Spectrally selective solar coating based on W-AlN cermet fabricated by
           reactive sputtering processes at high deposition rate

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      Authors: Antonio D'Angelo, Claudia Diletto, Salvatore Esposito, Giorgio Graditi, Antonio Guglielmo, Michela Lanchi, Gabriella Rossi
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The low cost fabrication of thermally stable solar coatings having high photo-thermal performance through high deposition rate processes represents one of the most demanding challenges in linear focusing Concentrated Solar Power (CSP) technology. Since 2005, ENEA has been developing and patenting solar coatings suitable for medium and high temperature applications based on the technology of double nitride cermet. The absorber layer of these coatings is characterized by a graded multilayer cermet of tungsten nitride and aluminium nitride (WN-AlN), while the ceramics of the antireflection filter are constituted by aluminium nitride (AlN) and silica (SiO2). The technology employed to deposit the ceramic component of all cermet materials, as well as of the antireflection filter, is reactive magnetron sputtering in poisoned mode, which does not allow obtaining the best trade-off between deposition rate and energy consumption. In order to improve the economic feasibility of linear focusing CSP solar plant, a cost-effective process was developed in the present work to produce spectral selective coatings for solar receiver tubes. To achieve this objective, the reactive magnetron sputtering technology in transition mode was applied to deposit all ceramic constituents of solar coatings. In detail, the antireflection ceramics were deposited through “dual magnetron” reactive sputtering in transition mode with Medium Frequency (MF) supply and using a Plasma Emission Monitoring (PEM) control system to maintain unchanged the target conditions during the process. It was found that, when using this technology in place of that in poisoned mode, the deposition rate improves by 1.6 and 2.3 times for AlN and SiO2, respectively. Regarding the graded multilayer cermet, while the ceramic component was deposited by “dual magnetron” reactive sputtering in transition mode with MF supply, the metallic component was deposited by “standard magnetron” sputtering with Direct Current (DC) supply. The process control through PEM system was simplified in this case by introducing N2 only from the gas-ring around the Al targets. Since in this configuration the reactive gas flow was not sufficient to promote the formation of WN as metallic component inside the cermet, the double nitride cermet WN-AlN was replaced by W-AlN. A fast procedure was developed to grow the W-AlN multilayer cermet by employing only one hysteresis curve to control the deposition process and grow the cermet layers in sequence. Specifically, this method presents the advantage that it is not necessary to stop and re-start PEM control, power supply and gas injection between the deposition of consecutive cermet layers. The fast procedure was applied to fabricate the absorber layer of the solar coating allowing to obtain a 44% reduction in the energy consumption by replacing WN with W as a metallic component of the multilayer cermet. The coating was subjected to a stability study at high temperature including the estimation of thermal degradation of the photo-thermal parameters after heat treatments under vacuum (2·10−2 Pa) for a total duration of 33 days at the temperature of 620 °C. The results revealed that no appreciable modification occurred in terms of solar absorptance (αs), while a very small increment of thermal emittance (εth) was evaluated at 400°C, thus demonstrating the excellent thermal stability of the produced coating.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:09Z
      DOI: 10.1063/5.0086711
       
  • A guideline for realistic accelerated aging testing of silvered-glass
           reflectors

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      Authors: Johannes Wette, Florian Wiesinger, Florian Sutter, Francisco Buendía-Martínez, Aránzazu Fernández-García
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Accelerated aging testing can be a useful tool to evaluate the durability of solar reflectors for CSP applications. The selection of suitable testing procedures and parameters is essential to be able to create viable results. Despite important research efforts in the past, there is still a lack of agreement on the selection of these tests for silvered-glass mirrors and only one standard was published so far. This standard presents a series of tests without acceptance criteria and still lacks a correlation to real outdoor results. In this paper a guideline is presented that helps to select tests and parameters for silvered- glass mirrors for different purposes. All parameters are determined based on the correlation of outdoor data and the respective accelerated test results for a variety of different materials. On one hand, it allows for quick and easy screening for degradation mechanisms and the direct comparison of the durability of different materials. On the other hand, more complex lifetime prediction procedures are presented that enable the estimation of the behavior of the reflector materials depending on the foreseen exposure site. Depending on defined maximum degradation by the user, acceptance criteria for the accelerated tests are proposed. The development of the guideline into an international standard within the IEC framework is ongoing.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:09Z
      DOI: 10.1063/5.0085744
       
  • Wireless communication for a modular heliostat field

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      Authors: Andreas Denan Liebenberg, Willie Smit
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The global demand for affordable renewable energy has driven Stellenbosch University's Solar Thermal Energy Research Group (STERG) to design and construct a modular heliostat field using their HelioPod technology. The next generation heliostat field will require a wireless communication network with sufficient capacity, range, throughput, and low latencies. The purpose of this study is to evaluate the feasibility of wireless communication within a CST field by means of practical tests aimed to determine the influence of interference, dense networks, and range on the network performance. An overview of the main limiting factors for wireless communication in a CST field are discussed and the network's software and hardware design are presented. Wireless communication is found to be a feasible option within a CST plant provided that care is given to place all nodes with line of sight to the access point and all neighboring networks operate in non-overlapping frequencies.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:09Z
      DOI: 10.1063/5.0089824
       
  • Thermoeconomic analysis of flexible heat integration in concentrated solar
           power plants Relative to geographical location

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      Authors: Kevin Ellingwood, Kody Powell
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Hybridization of concentrated solar power (CSP) plants with dispatchable fuels allows flexibility in plant operation that improves the economic competitiveness of CSP. This study assesses the impact that plant location and design solar multiple have on the thermodynamic performance and levelized cost of hybrid CSP plants employing flexible heat integration (FHI). Flexible heat integration is a systems-level operation concept where the collection temperature and integration of solar energy within a CSP plant shift in response to off-design and variable solar irradiance. The study involves three locations that demonstrate varying amounts of solar energy each year: Salt Lake City, Utah; Reno, Nevada: and Las Vegas, Nevada. Further, the performance is studied at solar multiple values of 1.6, 1.8, and 2.0, and FHI operation is compared to the more rigid base-level hybrid and standalone CSP schemes. The results show that hybridizing can drastically improve solar-to-electric efficiency (ηSTE) and levelized cost of electricity (LCOE) at all locations relative to standalone CSP operation. In Las Vegas, for instance, FHI operation exhibits an ηSTE of 14.1% at a solar multiple of 2.0, which is drastically improved from the ηSTE of 12.3% demonstrated there by a standalone CSP system. The relative improvement from FHI is more drastic in Salt Lake City, with the ηSTE improving from 10.9% to 13.2%. Likewise, the LCOE of the base-level hybrid plant at Salt Lake City is significantly lower at $122.3/MW with a solar multiple of 1.6 whereas the equivalent standalone CSP plant demonstrates a levelized cost of more than $260/MWh. The LCOE of the hybrid plant with FHI increases slightly to $124.3/MWh due to a more complex thermal energy storage system despite lower annual fuel costs due to improved solar-to-electric efficiency, which corresponds to higher solar fractions, or solar shares. The results here imply that hybridization can improve the economic potential of CSP systems outside of the current geographical deployment of CSP plants.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:08Z
      DOI: 10.1063/5.0086318
       
  • Simulating and validating systemic advantages of using advanced control
           systems and modular sodium CSP configurations to maximize component
           reliability and plant availability

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      Authors: Buddhi Ranasinghe, Kurt Drewes
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      This paper outlines the development of a high-resolution dynamic process model for a concentrating solar thermal plant with Vast Solar's proprietary advanced temperature control system and a distributed piping network using liquid sodium as a heat transfer fluid. The results of validation testing completed at Vast Solar's pilot plant in Jemalong, Australia and commercial scale simulations are described. Furthermore, the paper highlights the importance for the industry to move towards high temporal resolution modelling.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:08Z
      DOI: 10.1063/5.0086317
       
  • Etendue-matched solar tower beam-down system for high-temperature
           industrial processes

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      Authors: Diogo Canavarro, Gonçalo Delgado, Vikas Patil, Manuel Blanco, Pedro Horta
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The standard Concentrating Solar Thermal (CST) mono-tower technology, which uses one receiver placed on top of a tower to which all heliostats in the heliostat field aim to, is regarded as one of the best and most promising technologies for various CST-driven applications, namely CST power plants, solar metallurgical processes, thermochemical production of solar fuels and waste materials recycling. However, the technology has some technical challenges concerning optical performance/tolerances, system dimensions, operation and maintenance issues, etc. An alternative to this standard CST mono-tower technology is the so-called beam-down technology, where a special mirror is placed on the top of the tower, instead of a receiver, to redirect the incident radiation from the heliostat field onto a receiver/reactor placed closer to the ground and potentially delivering higher concentrations at the receiver than the standard CST mono-tower technology. This paper presents a new approach to improve the optics of beam-down systems, applies it to the optical design of a specific system, and shows the optical behavior of this design at two locations: Évora (Portugal) and Hurghada (Egypt). The approach uses etendue-matching between all the optical stages to minimize the optical losses between them. To analyze the optical behavior of the system designed, as an example, using the etendue-matching approach, raytracing simulations were carried out and are presented also in the paper.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:08Z
      DOI: 10.1063/5.0085900
       
  • Preface: SolarPACES 2020 – 26th International Conference on
           Concentrating Solar Power and Chemical Energy Systems

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      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.

      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:07Z
      DOI: 10.1063/12.0009334
       
  • Progress in the development of a laser and camera system for the
           calibration of heliostat fields of central receiver systems

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      Authors: Johannes Christoph Sattler, Joachim Göttsche
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      This work presents the current state of progress of a heliostat field calibration system based on a central laser and camera method. The method foresees that a laser beam is emitted onto a facet of a heliostat, which reflects the beam into the sky. Upon traversing the sky, light is scattered away from the beam. Two cameras take an image of the beam from two different angles such that a 3-D vector and from that the normal vector of the mirror facet can be computed. First indoor tests were carried out with an ultraviolet (UV) Q-switched pulsed laser with central wavelength of 355 nm that was specially modified and features a beam diameter of 47 mm. Two types of cameras were tested to take the image of the laser beam. Topics that include the laser type and wavelength, laser safety, atmospheric extinction, camera and lens technology as well as options of ultra-narrow bandpass filters had to be scrutinised and technology carefully matched. An insight into the most significant topics and theory as well as the validation of the theory is given in the following chapters.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:07Z
      DOI: 10.1063/5.0086273
       
  • Performance analysis of variable speed solar gas turbine configurations

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      Authors: Matthew R. Meas, Theodor W. von Backström, Sybrand J. van der Spuy
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      In solar gas turbines, the conventional integration of the core compressor and turbine into a single “spool” can impede optimal flow through the blade passages in the components for a given thermal energy input and load. This affects the efficiencies of the compressor and turbine components, and the performance of other components in the flow circuit that are sensitive to the pressure and mass flow rate of the working fluid, such as the solar receiver. In principle, flow compatibility between the various components in a solar gas turbine can be improved if the compressor and turbine rotor speeds can be made to adapt to changing conditions in the flow circuit. Such deconstructed configurations are used in electrically assisted turbochargers and appear in various concepts for next-generation jet engines. In this work, different variable speed gas turbine configurations are simulated, and their performance compared with that of conventional single- and two-shaft engines to quantify the improvement, if any, that can be attained. The findings show that variable rotor speeds can enable the average quantity of thermal energy harnessed by the solar receiver to be increased by 8.46 %, and the average fuel consumption in solar hybrid operation to be reduced by 15.1 % compared to the reference. The effects of the component sizes on the observations are described, limitations of the analysis are identified, and possible implications of the findings for the costs and emissions of solar gas turbine systems are discussed.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:07Z
      DOI: 10.1063/5.0086271
       
  • Biomass–solar thermal hybridization using Carnot batteries for s-CO2
           Brayton cycles

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      Authors: Robert Valencia-Chapi, Miguel López-Guillem, Luis Coco-Enríquez, Javier Muñoz-Antón
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Carnot batteries represent state-of-the-art technology in the fields of thermal energy storage and dispatchable electricity generation. The thermal energy usually comes from solar thermal power plants. The present study analyzes and optimizes a hybrid biomass–solar thermal central tower power plant coupled with a carbon dioxide cycle in a supercritical state and thermal energy storage, known as a Carnot battery system. Thermal and economic optimization were carried out for the power cycle, thermal storage, biomass, and the power plant’s main parameters to obtain the current available minimum levelized cost of energy, LCOE.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:07Z
      DOI: 10.1063/5.0086031
       
  • Aerodynamic analysis of wind loading on parabolic trough collectors using
           high-fidelity CFD modeling

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      Authors: Shashank Yellapantula, Ganesh Vijayakumar, Devon Kesseli, Shreyas Ananthan, Mark Mehos
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Wind loading on parabolic solar collector support structures is the key driver for material costs. As identified by NREL's CSP Best Practices project [1], ability to predict wind-loading in deep-arrays and the impact of edge effects has potential to decrease levelized cost of electricity (LCoE) by 15%. In this study, we present a high-fidelity computational model that can model the flow around deep arrays of parabolic troughs under varying turbulent inflow conditions. Ability to accurately reproduce atmospheric boundary layer (ABL) profiles is first demonstrated through Large Eddy Simulation (LES) simulations and compared against wind tunnel measurements. Thereafter, unsteady turbulent flow past single row and six row configurations is computed using hybrid RANS/LES simulations. Investigations of wind loading, through parametric tilt angle variations of single row and on waked collectors in six-row configuration, are used to highlight design considerations for parabolic troughs only possible through high-fidelity unsteady calculations.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:06Z
      DOI: 10.1063/5.0087124
       
  • On the optical characterization of heliostats through computational
           optimization

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      Authors: Rafael Monterreal-Espinosa, Nicolás Calvo-Cruz, Juana López-Redondo, Jesús Fernández-Reche, Raul Enrique-Orts, Pilar Martínez-Ortigosa
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The optical quality of heliostats is highly relevant in solar power tower plants. This information, along with an appropriate heliostat image simulation model, allows for predicting multiple variables on the receiver surface at any time. Some of them are the irradiance concentration factor, the image radius containing a certain percentage of the power, and spillage. However, there are no optical quality characterization routines in industrial electro-solar tower power plants. The reason is that optical characterization is a complex and time-demanding process requiring knowledge of image acquisition and analysis methods. This article defines an optical characterization methodology for heliostats that combines the traditional methods with numerical optimization algorithms. Namely, the process starts by acquiring a reference image of the system under study. After that, the image must be fitted to an optical model considering the optical structure under study and the corresponding variables. Fitting is equivalent to finding the values for the variables of the optical model that minimize the difference between the real image observed and that synthetically generated by the model. This task has traditionally been carried out through semi-automatic trial-and-error strategies, but this work proposes using heuristic global optimization algorithms instead. To assess the effectiveness of this proposal, the results of three global optimizers, i.e., Teaching-Learning-based Optimization (TLBO), Universal Evolutionary Global Optimizer (UEGO) and Multi-Start Interior-Point, have been compared to those traditionally achieved by an expert with a spherical heliostat facet. According to the results obtained, the parameter set found by TLBO and UEGO features between 6 to 8% lower root-mean-square deviation, which supports their use for optical characterization over trial-and-error.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:06Z
      DOI: 10.1063/5.0085747
       
  • Supercritical CO2 mixtures for Brayton power cycles complex configurations
           with concentrating solar power

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      Authors: Robert Valencia-Chapi, Paul Tafur-Escanta, Luis Coco-Enríquez, Javier Muñoz-Antón
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      An evaluation of the impact of using supercritical carbon dioxide mixtures (s-CO2/C2H6, s-CO2/CH4, s-CO2/Kr, and s-CO2/SF6) as a working fluid is made here for Brayton s-CO2 power cycles. The considered complex configurations include recompression with two reheating (RCC–2RH), recompression with three reheating (RCC–3RH), recompression with main compressor intercooling and two reheating (RCMCI–2RH), and recompression with main compressor intercooling and three reheating (RCMCI–3RH), which were coupled to a linear-focus solar system with Solar Salt (60% NaNO3/40% KNO3) as the heat transfer fluid (HTF). The design parameters evaluated the solar plant performance at the design point, the aperture area of the solar field, and variations in costs regarding the plant’s total conductance (UAtotal). The methodology used to calculate the performance established the total conductance values of the heat recuperator (UAtotal) to between 5 and 25 MW/K. The main conclusion is that the cycle efficiency has a considerable improvement compared with that obtained using pure s-CO2. The s-CO2/Kr mixture with a molar fraction ratio of 30/70 increases the cycle efficiency between 7–11% relative to pure s-CO2 and as a function of the UAtotal. The s-CO2/CH4 mixture with a molar fraction of 45/55 increases between 3–7%, and the s-CO2/C2H6 and s-CO2/SF6 mixtures only increase between 1– 2%. For the solar field unitary costs, the s-CO2/Kr mixture has the lowest cost at $29–34 million USD, which depends on the solar field aperture area and the UAtotal for the RCC-2RH and RCMCI-2RH configurations. Finally, the results demonstrate that variations in the working fluid properties play a significant role due to the positive impact on the increased thermal efficiency of the s-CO2 Brayton cycle when using the RCC and RCMCI configurations.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:06Z
      DOI: 10.1063/5.0086032
       
  • Use of the ND tool: An open tool for the synthetic generation of 1-min
           solar data from hourly means with geographic flexibility

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      Authors: Miguel Larrañeta, Carlos Cantón-Marín, Manuel Antonio Silva-Pérez, Isidoro Lillo-Bravo
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      In this paper, we present a description of how to use a web based tool employing the ND model by Larrañeta et al. [1]. The tool is suited for downscaling DNI, GHI or coupled DNI and GHI from 1-h to 1-min. It requires only an annual solar radiation dataset in the hourly resolution as input and provides 1-min data in any location without local adaptation. We have applied the tool in three locations with different climates. The similitude between measured and generated DNI distributions has been evaluated through the Kolmogorov-Smirnov test Integral (KSI) for annual synthetic 1-min datasets. Obtained KSI values range from 6.2 W/m2 to 11.5 W/m2
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:06Z
      DOI: 10.1063/5.0085901
       
  • The influence of optical characterization at different angles of incidence
           on optical efficiency calculation of a novel small-size parabolic trough
           collector for process heat applications

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      Authors: Leticia Aldaz, Xabier Randez, Amaia Mutuberria, Fabienne Sallaberry, Estelle Le Baron, Angela Disdier
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      In this study the impact of considering angle dependent optical properties for analyzing the optical performance of a parabolic-trough collector (PTC) is presented. It intends to address the realistic parabolic-trough behavior when simulating optical efficiencies and Incidence angle modifier (IAM). For this purpose a real optical characterization in laboratory of the materials of a PTC prototype as a function of the incidence angle was performed (reflectance and transmittance). The characterization has been done under SFERA III program framework at CEA facilities. In a second stage an analysis using the ray tracing tool Tonatiuh has been done to calculate the optical efficiencies and the IAM for the proposed PTC. Two optical models are defined, with and without angle dependent optical properties. For the cases analyzed, the results show that the loss of efficiency is not unneglectable when angle dependence optical properties are taken into account. For this reason, using unique nominal values for the optical properties of the materials may cause the overestimation of optical efficiencies.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:05Z
      DOI: 10.1063/5.0085907
       
  • Thermal storage filler material distribution for the polyphem project

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      Authors: Margarita M. Rodriguez-Garcia, Esther Rojas, Juan M. Caruncho
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The aim of the POLYPHEM project (H2020 program, Ref N. 764048) is to increase the flexibility and improve the performance of small solar tower power plants. The concept consists in implementing a combined cycle formed by a solarized micro gas-turbine and a Rankine organic cycle machine, with an integrated thermal storage device between the two cycles. The need for cooling is minimal. A prototype plant of 60 kWel with a thermal storage of 2 MWh net capacity is designed, built and installed on the site of the experimental solar tower of Themis in Targasonne (France). The objective of the project is to validate the technical choices under test conditions representative of actual operating conditions. Among the options of thermal energy storage (TES) a thermocline tank with solid filler and thermal oil as heat transfer fluid has been selected. The selected oil, Jarytherm DBT, presents very low vapor pressure (45999 Pa (abs), i.e. -0.55 barg at 340 °C), which allows for a storage tank at atmospheric pressure. The thermal storage concept to design is a thermocline tank with concrete for walls, foundations and filler. The filler is made of bricks, so it is expected to avoid most of the thermal ratcheting issues associated to fillers. This paper presents the different internal disposals of the bricks in the tank, and the influence these disposals may have both on the thermohydraulic behavior of the storage thermocline tank and on the stored energy.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:05Z
      DOI: 10.1063/5.0085749
       
  • 200 MWth and 1 MWth chloride salt to supercritical carbon dioxide heat
           exchanger and test integration designs

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      Authors: Matthew D. Carlson, Dereje Amogne, Dwight Dorsey
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The Generation 3 Concentrating Solar Power Liquid Pathway (G3LP) proposes the use of a ternary chloride molten salt as a heat transfer fluid and thermal energy storage (TES) media with heat input from a sodium receiver loop and heat removal by a supercritical carbon dioxide (sCO2) Brayton cycle to reduce the levelized cost of energy of commercial CSP plants to 6 ¢/kW-hr in line with the U.S. Department of Energy SunShot targets. This system architecture requires a primary heat exchanger (PHX) between the ternary chloride salt TES and the sCO2 working fluid of the power cycle operating up to 720 °C with a 30-year lifetime, high reliability, and low cost. The combination of a highly corrosive high-temperature fluid on one side and a high pressure and temperature fluid on the other suggests the need for a compact high-performance heat exchanger in order to reduce the amount of corrosion-resistant material required for fabrication and allow for small channel diameters to more easily contain the operating pressure of the sCO2 at high temperatures (>700C). This paper presents the results of the G3LP design for a compact salt to sCO2 heat exchanger scalable to a 200 MWth commercial plant size with a 1 MWth detailed design for demonstration with a G3LP Phase 3 pilot plant.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:04Z
      DOI: 10.1063/5.0089316
       
  • A practical simulation method to estimate fusion enthalpy of phase change
           materials eutectic mixtures for CSP plant applications

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      Authors: Tiziano Delise, Anna Chiara Tizzoni, Emiliana Mansi, Annarita Spadoni, Luca Turchetti, Cadia D'Ottavi, Natale Corsaro, Salvatore Sau, Silvia Licoccia
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      The determination of fusion enthalpy of ternary eutectic mixtures of molten salt was crucial for the development of feasible PCM material. A simulation method was presented as a suitable and fast way to estimate a first rough value of latent heat. The approach was validated by calorimetric measurements using five eutectic mixtures composed by alkaline nitrates and nitrites. At this aim, the binary fitting parameters determined in previous works were collected and then employed to estimate the latent enthalpy of the corresponding ternary mixtures, according to a thermodynamic model based on the regular solution assumptions. The obtained values were confronted with the experimental measurements, resulting in a discrepancy of about 15%.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:04Z
      DOI: 10.1063/5.0085751
       
  • Experimental results from a pilot scale latent heat thermal energy storage
           for DSG power plants – Advanced operating strategies

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      Authors: Pierre Garcia, Grégory Largiller, Gilles Matringe, Lucas Champelovier, Sylvie Rougé
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Since 2013, CEA has been operating a pilot scale high pressure water-steam facility called LHASSA designed to test latent thermal energy storage modules under operating conditions similar to commercial Direct Steam Generation CSP plants. A Phase Change Material (PCM) storage module connected to this facility is composed of aluminum finned steel tubes immerged into sodium nitrate and surrounded by aluminum inserts for heat transfer enhancement. This paper presents the results obtained from the third test campaign on this storage module, consisting in 25 charge-discharge cycles under a wide range of operating conditions (fixed of sliding pressure, complete and partial charge levels…). Thermal performances of the storage test section show a very good repeatability, without any performance degradation compared to the previous test campaigns. Some new operating strategies were successfully tested (charge interruption simulating a cloud transient in the solar field, discharge with fixed pressure and varying mass flows, charge-discharge transition management).
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:04Z
      DOI: 10.1063/5.0085753
       
  • Experimental and numerical study of an air solid thermocline thermal
           energy storage system operating at high temperature

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      Authors: Elisa Alonso, Esther Rojas, Rocío Bayón
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      One-single tank for thermal energy storage works by creating a thermocline between a cold and a hot zone. This type of storage system can be up 35% cheaper than two-tank storage with molten salts. ALTAYR is a laboratory-scale prototype rock-air packed-bed tank capable of storing energy by forming a thermocline. It is available at the Thermal Storage and Solar Fuels Unit of CIEMAT-PSA and allows experimental tests to study the performance of a thermocline system in a wide range of operational conditions. The facility is presented in this work as well as some results of experimental tests that explore its performance. Moreover, an initiatory numerical model developed to better understand the technology and optimize the system design is presented. The model has been validated with the experimental results achieving good agreement. Further work is currently on going and it is devoted to the model refinement in order to be employed to design reliable and cost effective thermocline tanks.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:03Z
      DOI: 10.1063/5.0087655
       
  • Improvements in the techno-economic analysis of particle CSP systems

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      Authors: Luis F. González-Portillo, Kevin Albrecht, Clifford K. Ho
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      This study presents the improvements to the tool developed by Albrecht et al. [1] for carrying out technoeconomic analysis in particle-based CSP systems. The objective of these improvements is to better capture the physics of these systems, and thus to more accurately predict the LCOE. In the new version of the tool, heliostat field and power cycle are now simulated by external and reliable software, and the receiver model is enhanced with the help of ray-tracing and CFD simulations. The new improvements offer more reliable results, some of them substantially different from those obtained with the previous model. The results obtained with the previous model and the new are compared in parametric analysis of the LCOE as a function of solar multiple, thermal energy storage and particle material. Both models show similar trends in the analysis of solar multiple and thermal energy storage, although the new model, with bigger potential of optimization, achieves a lower minimum LCOE. In the analysis of the particle material, the new model shows that high-absorptivity particles such as CARBO HSP achieve lower LCOE than low-absorptivity particles such as sand even if the latter were free, while the previous model showed the opposite.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:02Z
      DOI: 10.1063/5.0085873
       
  • Chinese CSP for the world'

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      Authors: Richard Thonig, Alina Gilmanova, Jing Zhan, Johan Lilliestam
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      For three consecutive five-year plans since 2006, China has worked on building up an internationally competitive CSP industry and value chain. One big milestone in commercializing proprietary Chinese CSP technology was the 2016 demonstration program of 20 commercial-scale projects. China sought to increase and demonstrate capacities for domestic CSP technology development and deployment. At the end of the 13th five-year period, we take stock of the demonstrated progress of the Chinese CSP industry towards delivering internationally competitive CSP projects. We find that in January 2021, eight commercial-scale projects, in total 500 MW, have been completed and three others were under construction in China. In addition, Chinese EPC’s have participated in three international CSP projects, although proprietary Chinese CSP designs have not been applied outside China. The largest progress has been made in molten-salt tower technology, with several projects by different companies completed and operating successfully: here, the aims were met, and Chinese companies are now at the global forefront of this segment. Further efforts for large-scale demonstration are needed, however, for other CSP technologies, including parabolic trough - with additional demonstration hindered by a lack of further deployment policies. In the near future, Chinese companies seek to employ the demonstrated capabilities in the tower segment abroad and are developing projects using Chinese technology, financing, and components in several overseas markets. If successful, this will likely lead to increasing competition and further cost reductions for the global CSP sector.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:02Z
      DOI: 10.1063/5.0085752
       
  • Can concentrated solar-driven supercritical CO2 power cycles help address
           the energy-water nexus'

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      Authors: Amr Omar, David Saldivia, Amir Nashed, Qiyuan Li, Robert A. Taylor
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Sustainable electricity generation plants can be coupled with energy-intensive desalination processes, but does this pose an attractive — and sustainable — solution for the energy-water nexus' Previous work by the co-authors has identified that among all desalination technologies, multi-effect distillation (MED) is the most promising technology for integration with concentrating solar thermal plants, because it can re-use ‘free’ waste heat from turbine exhaust, albeit at the cost of reduced electricity output. This study investigates if this approach can be beneficially extended to a solar-driven supercritical CO2 (sCO2) cycle. It was found that for low water production levels (i.e., 6 kWh/m2 · day).
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:02Z
      DOI: 10.1063/5.0085634
       
  • Ray tracing method for mirror’s geometry evaluation of a central tower
           concentration solar power system

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      Authors: Héctor D. García-Lara, Arturo Morales-Fuentes, Mario A. Gallegos
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      A method for evaluating the yearly performance of a solar concentrator is used. The simulation is carried on using the commercial forward ray-tracing tool TracePro in conjunction with MATLAB. Ray tracing methods are commonly used to evaluate a solar concentrator's performance; however, some implementations oversimplify the simulation process and only consider a small representative number of scenarios throughout the year. For example, summer and winter solstices for tracking studies or monthly averages for evaluating the system's annual average output. The present method considers a year-long simulation on an hourly basis using MATLAB to set up step-by-step simulation within TracePro via the Dynamic Data Exchange (DDE) protocol; for increased fidelity, hourly irradiance data from Meteonorm is also taken into account. Given a defined mirror configuration, different mirror geometries are evaluated to determine the cosine, shadows, blockage, and spillage losses to compare on annual overall performance.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:01Z
      DOI: 10.1063/5.0085636
       
  • Designing a lab-scale vibrating solar receiver for a linear beam-down
           solar field

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      Authors: Sebastián Taramona, Jesús Gómez-Hernández, Javier Villa Briongos, Domingo Santana
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Concentrated Solar Technologies can be applied in the heating and drying processes in industry. This work proposes a design for a particle receiver based on rotating vibratory motors, creating an easily adjustable vibratory conveyor. This way, knowing the total mass of the conveyor we can regulate the flow rate of particles by adjusting the vibration angle. Since the main advantage of the proposed technology is the mixing of the top and bottom layers of particles we also explore the effect of different parameters in the behavior of the particles inside the bed and their influence on the mixing rate.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:01Z
      DOI: 10.1063/5.0085755
       
  • CSP-reference power plant “Made in Germany”

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      Authors: Jürgen Dersch, Matthias Binder, Cathy Frantz, Stefano Giuliano, Fabian Gross, Holger Hasselbach, Nadine Kaczmarkiewicz, Freerk Klasing, Jaime Paucar, Thomas Polklas, Christian Schuhbauer, Axel Schweitzer, Alexander Stryk, Dennis Többen
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      A reference solar tower power plant with molten salt as heat transfer and storage medium has been designed. In addition to the general layout of this plant, the paper contains selected details about component sizing and optimization. The final layout and optimization of the least cost storage capacity for 2 different operating schemes has been checked by an annual yield calculation for an exemplary site in Morocco.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:00Z
      DOI: 10.1063/5.0085877
       
  • Studies of specular reflectance distribution for aged or degraded solar
           mirrors

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      Authors: Antoine Grosjean, Estelle Le-Baron, Anna Heimath
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      One of the key challenges for the CSP industry is to offer high-performance solar mirrors lasting two or three decades, at the lowest cost. For CSP, the performance criteria must include a high solar reflectance (up to 90%) with high specular reflection, i.e. the solar flux must reflect with an acceptance angle as small as possible. In this study, we have compared the reflected power distribution (the acceptance angle) of different commercial solar mirrors: new, soiled or natural and artificially aged. The measurements were performed using VLABS setup, at the Fraunhofer Institute in Germany. The objective is to make sure that different levels of ageing or soiling on the mirrors do not alter the power distribution, depending on the aperture angle. We conclude that all mirrors tested are good candidates. The analyses show that soiling or ageing do not alter the size of the specular reflection spot. All degraded, soiled and/or aged mirrors are able to focus the sun light with the same concentration ratio than new mirrors.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:59:00Z
      DOI: 10.1063/5.0086603
       
  • Particle CSP plant: Quantifying system benefits through production cost
           modeling

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      Authors: Cara Libby, Qin Wang, Aidan Tuohy, Clifford K. Ho, Bruce Kelly, Henry Price
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      Next-generation central receiver concentrating solar power systems (Gen3 CSP) are targeting operating temperatures above 700°C and use of a closed Brayton power cycle with supercritical CO2 (sCO2) as the working fluid. These systems intend to deliver greater value through improved operating efficiency, dramatic cost reductions, and improved ability to provide grid benefits. EPRI conducted production cost modeling to quantify potential system benefits for a particle-based Gen3 CSP technology developed by Sandia National Laboratories. The model explores dispatch strategies for a Particle CSP Plant and determines changes in annual system operating cost, plant revenue, and locational marginal price (LMP). Sensitivity analysis is used to identify scenarios and market conditions in which the technology is competitive, such as high penetrations of variable solar photovoltaics (PV) and wind. The model is intended to quantify the unique value proposition for the Particle CSP Plant.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:58:59Z
      DOI: 10.1063/5.0087099
       
  • Modeling of a loop thermosyphon supplying solar energy to a desalination
           boiler

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      Authors: Josh Charles, Nathan Van Velson, Jianjian Wang, Sean Hoenig
      Abstract: AIP Conference Proceedings, Volume 2445, Issue 1, May 2022.
      A new concentrated solar desalination system based on a two-phase working fluid with volumetric solar absorption is under development. This system promises to improve overall solar to thermal efficiency and reduce parasitic power by taking advantage of the passive flow circulation of a loop thermosyphon. To predict system performance, a two-phase loop thermosyphon model was developed around well-validated, two-phase frictional pressure drop correlations. The model was used to analyze pressure drops and resulting fluid saturation temperatures throughout the loop. Good agreement was found between the predicted fluid mass flow rate and that measured in a lab-scale prototype loop thermosyphon. The model continues to be developed and will be validated against a larger-scale prototype system.
      Citation: AIP Conference Proceedings
      PubDate: 2022-05-12T02:58:59Z
      DOI: 10.1063/5.0086288
       
 
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