Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: — The paper analyzes the potential use of porous ceramic materials as absorbers for hydrogen storage in the gaseous state and shows the prospect for the use of a steel reactor container filled with porous ceramic absorbers as an efficient hydrogen accumulator. PubDate: 2022-10-01
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Using the solar thermal system in the agricultural area to conserve fruits and vegetables has shown to be a practical and economically feasible approach. In this research paper, the performance analysis of indirect solar dryer was investigated. Using various heat-absorbing materials, heat can be stored in the form of internal energy during the day time, and same heat can be used in night conditions to get desired results as per requirements. The onion and garlic were dried in the indirect natural solar dryer under three different cases like conventional, granite with silica gel and nitrate salt (also called sodium nitrate salt: NaNO3) with silica gel method. The mentioned heat storing material and desiccant material’s effect on drying of onion and garlic were studied in each case. The relative humidity drop was observed around 1–2% due to silica gel. The maximum temperature achieved was 52.30°C in granite with silica gel case. Moisture content of the onion was reduced from 86% to 15% in 24 h in solar dryer in case of nitrate salt with silica gel method. For onion drying, moisture content was reduced in case of conventional and granite with silica gel cases up to 25 and 18% respectively, in the same time period (24 h). Moisture content of garlic was reduced from 70 to 56% in 24 h in solar dryer in case of nitrate salt with silica gel. For garlic drying, moisture content was reduced in conventional and granite with silica gel cases were from 70 to 60% and 70 to 57% respectively, in same time period (24 h). Hence the nutrients, color, and taste that are lost in the conventional method was preserved in the solar dryer. The experimental data were fitted for six different mathematical models. Statistical tools like root means square error, chi-square, and correlation coefficients were used to analyze the fitting curves. The logarithmic model showed the best-fitted model to describe the drying of onion and garlic. PubDate: 2022-10-01
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: The study is devoted to the development of a model for the analysis of current–voltage characteristics (CVCs) of perovskite based solar cells. Using the high-level programming language Python, programs have been developed for the theoretical calculation of the CVCs of perovskite based solar cells using the one- and two-diode models. The calculation results are compared with the experimental data on the CVCs of a perovskite solar cell consisting of an electron-conducting layer (n-type) SnO2 and SNO2–KCl. It has been established that the mathematical two-diode model most adequately reproduces the CVCs of perovskite based solar cells, especially under conditions of lower illumination. The developed program can be used to calculate and predict the CVCs for more efficient control of the output parameters of perovskite based solar cells. PubDate: 2022-10-01
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Wind energy is considered to be one of the fastest growing green energy resources. The time horizon of wind energy forecasting plays a crucial role in several end user applications. This study focuses on the short term (day ahead) and long term (multiple days to months ahead) forecasting of wind speed using time series and machine learning methods. For this, we first analyse time series plots of daily, weekly and monthly sampled wind speed data and perform stationarity test. Then, we implement time series SARIMA and window-sliding ARIMA models due to the presence of yearly seasonal patterns in the dataset. In addition, we implement two most popular machine learning models, namely MLP and LSTM, and compare their performance with the time series methods at different time scales. The experimental results based on 15 yr (2000–2014) of daily, weekly and monthly wind speed data at four different locations in India reveal that the window-sliding ARIMA has the best performance in terms of its lowest RMSE and MAPE values for daily data. For weekly forecasting, the performance of LSTM, MLP and the window-sliding ARIMA are very similar, whereas for monthly forecasting, the SARIMA model produces the least error values. In summary, the present study enables a generic guideline for the choice of wind speed forecasting models at daily, weekly and monthly time scales. PubDate: 2022-10-01
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Building performance simulation (BPS) is a cost-effective and time-efficient method of predicting the efficiency of energy-saving building modifications. The most common BPS tools for determining the contribution of PCMs to energy savings in buildings are EnergyPlus, TRNSYS, and ESP-r. One should note that in this study that PCM-models based on Modelica have been thoroughly compared at the whole-building performance simulation level. We evaluated the accuracy of the Modelica-based models of basic Cases 600, 600FF and 650FF compared to eight reference data from the ASHRAE Standard 140. After the evaluation of accuracy, various modified models of the cases with PCM layers were compared. The main purpose of comparison was to test and illustrate the PCM model’s modeling capabilities in the context of whole-buildings, rather than to focus on best solutions for single PCMs. Coefficients of determination for the created models of Cases 600FF and 650FF are 0.9998 and 0.9999, respectively. RMSEs for the created model of Cases 600FF and 650FF are 0.72 and 0.35°C, respectively. Finally, preliminary results of PCM integration in full structures revealed that precise analysis is required when constructing PCMs within building envelopes, as the dynamic thermal performance of buildings is highly dependent on many elements such as PCM layer characteristics and placement. PubDate: 2022-10-01
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: The possibility of using a graded-gap crystal as a protective coating of organic solar cells from harmful chemical and other external influences has been studied. On the basis of a quantum model for an electronic near-surface state with an Airy potential well, an expression is obtained that is radically different from the Tamm level, with the help of which the condition of light transparency of the graded-gap region is formulated, but with the implementation of protective properties due to a reduced band gap. It is assumed that the developed method is valid for both classical semiconductors and ionic materials. It was shown that graded-gap coatings have no electronic levels at a certain thickness and, therefore, do not absorb solar radiation; they are completely transparent and can also be used as encapsulating coatings for organic solar cells. Antireflection coatings based on MgF2–CaF2 composite materials are considered as an example of a graded-gap coating. Composite material MgF2–CaF2 is a homogeneous material with an ionic bond, so the coating based on it has graded-gap properties. Such coatings are antireflective and promising for encapsulation of organic solar cells. The increase in the transmission of a glass substrate with applied antireflection coatings is 1.68–2.27%, depending on the composition of the coating. After storage under normal conditions for 3 years (2018–2020) and climatic tests for 1 year (2021), the coatings retained their spectral–optical properties. The experiment showed that graded-gap coatings on organic solar cells are antireflective and protective from external influences. PubDate: 2022-10-01
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: — Changeability of the energy input from renewable sources, as well as climate change, accelerating by the day, dictate the need to study the latest climate changes in the country in order to examine the possibilities of using electricity generating installations and systems based on renewable energy sources, as well as for agro–climatic purposes in this territory. The first part of the research presents the results of studying the dynamics of changes in weather and climatic conditions in the territory of the Republic of Uzbekistan, the Fergana Valley in particular, during the period of 2005–2021 by means of collecting and processing climatic data obtained from nine weather stations located in the valley and suitable for scientific research purposes. It was revealed that during the period of 2005–2021, the maximum change in the average annual temperature in the areas of Fergana oblast was 1.58°C and the number of days with an average ambient temperature above +25°C varied between 100 and 121 days; direct beam solar radiation increased significantly; there was also a sharp drop in wind speed and the number of days with dust storm and drifting dust; and the amount of precipitation in the region in recent years was significantly less than in 2005. Due to the fact that the level of warming in the valley affects the generation capacity of crystalline silicon photovoltaic modules (PVMs), in order to predict their production capacities with the least error, it is necessary to prepare the most accurate source data on climatic and actinometrical parameters for their performance evaluation and survey works in the applicable part of the region. PubDate: 2022-10-01
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: In this work a novel compound W-trough based solar concentrator for photovoltaic applications is proposed. The proposed concentrator consists of flat reflectors that are easy to fabricate. The concentrator has a 3D configuration that offers superior effective concentration ratio compared to conventional 2D configuration. The concentrator features large acceptance angles in the x-direction, which promote its application in tracking free concentrators. The proposed design allows fine-tuning for acceptance angle based on the concentrator opening angle (i.e. trough angle). Finally, tuning the compound concentrator face angles is shown to be effective in improving the effective concentration ratio by about 21% and the illumination uniformity by about 49%. PubDate: 2022-10-01
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: The major challenges in solar photovoltaic (PV) penetration into the grid are maintaining quantity and quality of power at transmission and distribution network because of variable solar insolation levels, harmonics due to solar inverters, sudden increase or decrease in load on distribution network, etc. In the Indian context, solar energy penetration into the grid is still limited to rooftop and small-scale generation feeding power into the distribution grid typically at 440 V or 11 kV. The only energy penetration at the transmission level of 220 kV is developed and installed by Power grid corporation of India in Hyderabad, India. Thus, the integration of solar photovoltaic systems in terms of power quantity and quality at the transmission and distribution level is still a major challenge in the Indian subcontinent which has brought ample opportunities for power quality engineers and researchers to comprehensively deal with issues related to quantity and quality of power supplied by solar PV technologies into the grid. The paper attempts to review existing status of Solar PV grid-connected applications from a qualitative and quantitative perspective and also comment upon its prospects with an emphasis on solar energy potential, installations done so far and expected quality of power in the grid- tied solar PV systems. PubDate: 2022-10-01
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: At the Joint Institute for High Temperature, Russian Academy of Sciences, a power plant scheme has been developed and implemented in the form of an operating test bed, which includes several energy sources (solar battery, electrochemical generator), a storing device (accumulator battery), a base load, and an additional consumer (an electrolyzer, a heat/cold generator, or redox-flow battery). All devices are connected to a common DC bus through individual matching converters that have the same hardware and software implementation. The created test bed with a data acquisition and processing system can be used to study various schemes for control of hybrid power plants, including not only renewable energy sources, but also selected groups of consumers for excessive production of hydrogen, heat, cold, and purified water. In the course of field tests, the possibilities of controlling energy flows due to the DC bus voltage control are demonstrated: the introduction of a guaranteeing source at night and the operation into an electrolyzer simulator during peak solar generation. PubDate: 2022-10-01
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: This article briefly provides information about a major system outage that occurred in the United Power System of Central Asia (UPS CA) on January 25, 2022 with the complete blackout of the power systems of Uzbekistan, Kyrgyzstan, and part of the power systems of South Kazakhstan. Recommendations to prevent the recurrence of such accidents in the future are proposed. Based on an analysis of the perspectives for the development of UPS CA, taking into account the expected large-scale integration of renewable energy sources (RESs) in the region, it is proposed to switch from the current parallel operation to joint operation of UPS CA with the Unified Power Systems of Kazakhstan and Unified Power System of Russia through a back-to-back DC station. PubDate: 2022-10-01
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: In this paper, the performance of thin film silicon solar cells is enhanced by employing 1D light-trapping structures. In order to design a structure which efficiently traps light, we have selected MgF2 and Al0.9Ga0.1As materials as the photonic crystal layers due to their negligible extinction coefficient within the silicon sunlight absorbing wavelength range. We have used a genetic algorithm for designing a back-reflector in order to increase the light absorption in the silicon layer. This increases the photocurrent of the solar cell and consequently, leads to an increased efficiency in the device. We have shown that an optimized 1D light-trapping structure can considerably enhance the efficiency of a thin-film silicon solar cell from 7.73% to almost 12%. This confirms the capability of properly designed 1D structures to improve the performance of solar energy conversion devices. PubDate: 2022-10-01
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: The study presents a numerical analysis of the parameters of the system for receiving solar vapor from a cylindrical collector with Syltherm800/Al2O3 nanofluid as a coolant. A 3D mathematical model of convective heat transfer in a heat sink has been developed, which takes into account the environmental conditions and the uneven distribution of the concentrated solar flux, calculated by the Monte Carlo method. The temperature dependence of the thermophysical properties of the nanofluid was found using empirical formulas. It has been proven that at an initial coolant temperature of 300 K and a speed of 4 m/s, adding 3, 5, and 8% of Al2O3 nanoparticles to the base coolant increases the heat transfer coefficient by 1.5, 3.4, and 7.8%, respectively. The problem of convective heat transfer was solved together with the hydrodynamic problem. The dependence of the Nusselt numbers of the considered coolants on the Reynolds numbers in the range from 0 to 55 × 104 is found. It has been determined that with an increase in the Reynolds number ( \(\operatorname{Re} > {{10}^{5}}\) ), the average Nusselt number for 3, 5, and 8% of Syltherm800/Al2O3 nanofluids increases by 7.66, 11.8, and 15.76%, respectively. The method of minimizing the production of entropy was applied to find the range of Reynolds numbers that determine the optimal thermodynamic parameters. For 3% Syltherm800/Al2O3 nanofluid, the optimal value of Reynolds numbers lies in the range \(20 \times {{10}^{4}} < \operatorname{Re} < 40 \times {{10}^{4}}\) . PubDate: 2022-10-01
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Algeria has high levels of untapped solar potential and it is necessary to find solutions that take advantage of this fact. Concentrated Solar Power (CSP) plants are one of the available renewable technologies which have more potential in regions with high direct solar radiations. In this study, CSP plant potential in selected regions of southern Algeria was optimized using the System Advisor Model (SAM) software. This takes into account the influence of various determinants and new technologies such as Stored Thermal Energy (STE), and backup system. The results show that the technical parameters (plant efficiency, annual energy produced, the solar field’s size, and the amount of STE) depend greatly on the plant’s technology, variations in DNI, and average atmospheric conditions especially ambient temperature and relative humidity. The Central Receiver Tower Power Solar Plant with storage thermal energy and backup systems using molten salt as heat transfer fluid and storage medium should be an option to take into account in the development of the Algerian system power compared to other solutions (SMopt = 2.8; LCOEopt = 15.11 Cent/kWh; CFopt = 87%; Annual Energy = 376 GW; FLHopt = 15 h). Therefore, the energetic potential in the selected site is estimated to be 400 GW. PubDate: 2022-10-01
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Photovoltaic (PV) modules may not experience uniform solar irradiation due to partial shading caused by the shadows of trees, passing clouds, or nearby buildings, resulting in a loss of energy. A robust real-time monitoring system and fault detection technique are highly critical to increasing the reliability of the PV system. This research focuses on developing real-time fault and partial shading detection techniques using Mamdani fuzzy logic for PV systems. The method has a minimal level of complexity and a high rate of fault identification. Multiple shading scenarios and open circuit fault were analyzed. Several rules have been developed in Mamdani fuzzy logic, which distinguishes between different cases. All case studies were verified through simulations and validated by establishing an experimental setup. From the simulation and experimental results, it has been demonstrated that the proposed technique has an excellent performance in detecting partial shading and fault. PubDate: 2022-10-01
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: SbxSey films were obtained by chemical molecular beam deposition (CMBD) on soda-lime glass substrates. Sb and Se were used as sources, their evaporation temperature was 950–1000°C (Sb) and 500°C (Se), the substrate temperature was maintained at about 500°C. Using scanning electron microscopy, X-ray diffraction analysis, and Raman scattering, the effect of the Sb/Se composition ratio on the structure of the synthesized films was studied. It was revealed that the films have a crystalline (orthorhombic) structure with compactly located crystallites having the form of rods with an average size: l = 4–8 µm (length) and d = 2–3 µm (diameter). PubDate: 2022-08-01
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: The article presents the results of studies on the effect of forward bias on the parameters of solar cells with the ZnO:Al/i-ZnO/CdS/CuIn1 – xGax(S,Se)2/Mo structure, which were previously subjected to reverse bias for 600 s. The results of studies of the current–voltage (I–V) characteristics of copper, indium, gallium, and selenide (CIGS) solar cells (SCs), before and after exposure to forward bias, indicate a difference in the effect of forward bias from exposure to long-term illumination, in which there is a restoration of parameters that have changed during reverse bias. Although the effect of forward bias is in some sense considered identical to the operation of a SC under illumination, when exposed to forward bias, further deterioration of the electrophysical parameters of the SC is observed, which can be interpreted on the basis of the charge state rearrangement model. PubDate: 2022-08-01
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Photoanodes play pivotal role in dye-sensitized solar cells (DSSCs). It serves the dual purpose of photo-sensitizer supporter, providing a larger surface area as well as a transporter for excited electrons from dyes to external circuits. Titanium dioxide ( \({\text{Ti}}{{{\text{O}}}_{2}}\) ) nanoparticles in the form of thin film photoanode, are of great scrutiny because of their tuneable band gaps ( \({{E}_{{\text{g}}}}\) ), cost-effectiveness, high stability and environment-friendly, assuring plenty of applications for visible light optical pursuits. Studies have been carried out with doped \({\text{Ti}}{{{\text{O}}}_{2}}\) with various metals and alloys combination and the effects of doping in the surface morphological structures, and electrical and optical attributes of the photo anode for DSSCs. In this study, undoped \({\text{Ti}}{{{\text{O}}}_{2}}\) nanoparticles have been synthesized with variation in precursors. Titanium isopropoxide (TTIP) and ethanol (EtOH) with different volumes are annealed at different temperatures using the sol-gel method and respective optical band gaps are derived and been studied. Furthermore, regression algorithms have been effectuated to predict the obtained optical band gaps. The experimental quotient concludes that the band gap of the photo anode varies from 3.2 to 3.38 eV. The regression models computation predicts the same resultants. Moreover, the metrics of regression reflects the same, through the mean square error (MSE), root-mean-square-error (RMSE), mean absolute value (MAE) and R2 being 0.001, 0.014, 0.009 and 0.907 respectively. PubDate: 2022-08-01
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Electricity saving potential of a residential air conditioning system based on a solar hybrid ejector-vapour compression refrigeration cycle operating with R245fa is investigated. The ejector refrigeration cycle of hybrid system is working with heat input from an integrated evacuated tube solar thermal collector which can produce temperature in the range of 60 to 100°C. Thermodynamic simulation of the vapour ejector flow is done using Engineering Equations Solver (EES) software to get its critical entrainment ratio and corresponding area ratio for various temperatures of evaporator and generator. The simulation results in terms of entrainment ratio is compared with published results to get maximum relative error within 3.1%. With evaporator temperature of 16°C and condenser temperature of 35°C, the critical entrainment ratio varies from 0.20 at 60°C generator temperature to 0.82 at 100°C generator temperature. The corresponding area ratio increases from 3.9 to 13.2. It is observed that for a given condenser temperature, and area ratio, the critical entrainment ratio increases with evaporator temperature but decreases with generator temperature. Analysis of the ejector refrigeration cycle with above range of operation shows that the refrigeration effect produced increases from 0.26 kW at generator heat input of 1.49 to 2.65 kW at heat input of 4.37 kW. Further, the analysis on one-ton hybrid air-conditioning system with ejector refrigeration producing its share of refrigeration system using solar heat input in the range of 60 to 90°C can lead to a compressor power saving in the range of 7.5 to 51.15% in comparison with standard vapour compression system of its kind. PubDate: 2022-08-01
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: A technology has been developed for manufacturing solar cells based on silicon doped with impurity atoms of rare-earth elements holmium and gadolinium. It has been established that at a concentration of doping with holmium and gadolinium of 1017 cm–3, the efficiency of solar cells increases on average by 15% relative to the control ones. An increase in the radiation resistance of solar cells based on silicon doped with rare earth elements holmium and gadolinium during irradiation with gamma quanta is shown. Rare-earth elements holmium and gadolinium, introduced into silicon during growth, are present in it in the form of various impurity precipitations and complexes, being electrically inactive, actively interacting with vacancies and residual impurities, reduce the concentration of optically active oxygen and carbon, increasing the thermal and radiation stability of the parameters of the original silicon. PubDate: 2022-08-01
Hybrid journal (It can contain Open Access articles)
[2467 journals]
