Subjects -> ENERGY (Total: 414 journals)
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ENERGY: GENERAL (7 journals)

Showing 1 - 7 of 7 Journals sorted alphabetically
Energy Research Journal     Open Access   (Followers: 3)
Greenhouse Gases : Science and Technology     Hybrid Journal   (Followers: 4)
International Journal of Energy Optimization and Engineering     Hybrid Journal   (Followers: 3)
International Journal of Powertrains     Hybrid Journal   (Followers: 2)
International Journal of Renewable Energy Development     Open Access   (Followers: 6)
Journal of Power Technologies     Open Access   (Followers: 6)
Journal of Thermophysics and Heat Transfer     Hybrid Journal   (Followers: 95)
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International Journal of Renewable Energy Development
Number of Followers: 6  

  This is an Open Access Journal Open Access journal
ISSN (Print) 2252-4940 - ISSN (Online) 2252-4940
Published by Diponegoro University Homepage  [16 journals]
  • Experimental Study of Rice Husk Fluidization Without a Sand Bed Material
           on a Bubbling Fluidized Bed Gasifier

    • Authors: Abeth Novria Sonjaya; Kania Safitri, Adi Surjosatyo
      Abstract: This study aimed to determine the effect of rice husk fluidization and variation in the equivalence ratio of bubbling fluidized bed gasifiers without sand bed materials. It also aimed to improve the fluidization quality by reducing the diameter of rice husks. Therefore, the bulk density increases, whereas voidage decreases, both of which are the main parameters for improving the quality of fluidization in solid particles. Experiments were carried out at a velocity of 0.82 m/s, by varying the equivalent ratios ranging from 0.20 to 0.35, and analyzing the syngas composition, cold gas and carbon conversion efficiencies, lower heating value, and temperature distribution. An equivalence ratio of 0.30 was obtained for a bubbling fluidized gasifier with syngas compositions of 7.415%, 15.674%, 3.071%, 17.839%, and 56.031% for H2, CO, CH4, CO2, and N2, respectively. Under these conditions, we obtained cold gas and carbon conversion efficiencies and a lower heating value of 31.340%, 37.120%, and 3.881 MJ/Nm3, respectively.
      PubDate: Sun, 01 Jan 2023 00:00:00 +000
  • Thermal Performance of Double Pass Solar Air Heater With Tubular Solar

    • Authors: Nassr Fadhil Hussein; Sabah T Ahmed, Ali L Ekaid
      Abstract: In this investigation, the effect of replacing the conventional solar absorber with a new solar absorber on the thermal performance of a double-pass solar air heater has been studied experimentally and numerically.  Three configurations have been introduced, the first configuration is a double pass solar air heater with a flat plate solar absorber (DPSAHWFP) for the aim of comparison, and the second configuration is a double pass solar air heater with a tubular absorber that includes a set of tubes which are fitted perpendicularly to the direction of airflow (DPSAHWT-1),  and the third configuration is double-pass solar air heater with a tubular absorber that involves set of tubes which are fitted in parallel to the direction of airflow (DPSAHWT-2). The experiments have been carried out under indoor conditions at a constant heat flux equal to 1000 W/m2 and different air mass flow rates (0.01– 0.03 kg/s). The results revealed that the air mass flow rate has a substantial impact compared to the rise in air temperature, hence, the thermal performance of solar air heater is directly proportional to increase air mass flow rate. In addition, the experimental and numerical outcomes indicated that for all air flow rates. The (DPSAHWT-2) offers higher thermal performance as compared to other models, where the maximum effective efficiency has been obtained at 0.03 kg/s equal to 80.9 %. Moreover, (DPSAHWT-2) is more efficient than DPSAHWFP and DPSAHWT-1 by 4.2 % and 9.8 % respectively.
      PubDate: Sun, 01 Jan 2023 00:00:00 +000
  • Study of Two Layered Immiscible Fluids Flow in a Channel with Obstacle by
           Using Lattice Boltzmann RK Color Gradient Model

    • Authors: Salaheddine Channouf; Youssef Admi, Mohammed Jami, Mohammed Amine Moussaoui
      Abstract: Lattice Boltzmann method (LBM) is employed in the current work to simulate two-phase flows of immiscible fluids over a square obstacle in a 2D computational domain using the Rothman-Keller color gradient model. This model is based on the multiphase Rothman-Keller description, it is used to separate two fluids in flow and to assess its efficacy when treating two fluids in flow over a square obstacle with the objective of reducing turbulence by adjusting the viscosities of the two fluids. This turbulence can cause major problems such as interface tracking techniques in gas-liquid flow and upward or downward co-current flows in pipes. So, the purpose of the study is to replace a single fluid with two fluids of different viscosities by varying these viscosities in order to reduce or completely eliminate the turbulence. The results show that to have stable, parallel and non-overlapping flows behind the obstacle, it is necessary that the difference between the viscosities of the fluids be significant. Also, showing that the increase in the viscosity ratio decreases the time corresponding to the disappearance of the vortices behind the obstacle. The results presented in this work have some general conclusions: For M≥2, the increase in the viscosity difference leads to an increasing of friction between fluids, reducing of average velocity of flow and decreasing the time corresponding to the disappearance of the vortices behind the obstacle. However, for M≤1/2, the opposite occurs.
      PubDate: Sun, 01 Jan 2023 00:00:00 +000
  • Optimization of a Management Algorithm for an Innovative System of
           Automatic Switching between Two Photovoltaic and Wind Turbine Modes for an
           Ecological Production of Green Energy

    • Authors: Yahya Lahlou; Abdelghani Hajji, Mohammed Aggour
      Abstract: Today, renewable energy and energy efficiency are key to limiting global warming and preventing the dangerous effects of climate change. The biggest problem with conventional solar and wind turbine systems is the intermittency of electrical power generation. Even if these two energy sources can be complementary, the space occupied by these hybrid systems remains very important. This work proposes an improved management algorithm for a patented transformable photovoltaic-wind system, which mainly uses two flexible photovoltaic panels which are automatically deformed by an electromechanical system from the planar shape to the semi-cylindrical shape of the Savonius wind turbine blades. When weather conditions change, this system switches to eco-friendly photovoltaic (PV) or wind turbine (WT) mode, allowing a good total power generation from two solar power sources or wind turbine power. The contribution brought for this work relates to the realization and the improvement of the management algorithm to determine a better change to the mode PV or the mode WT. The operation test was simulated in 8760 hours for the year 2021. This developed algorithm allows several theoretical calculations of the power produced from solar radiation and wind speed data, thereafter the algorithm compare and determines the overall power and selects the optimal PV or WT mode. In this study, the overall power generated by the invented system produces more electricity per hour, the power Pt increases by 75.55% compared to the power Pwt, and also the power Pt increases by 68.15% compared to Pvp power.
      PubDate: Sun, 01 Jan 2023 00:00:00 +000
  • An Investigation into the Role of Tourism Growth, Conventional Energy
           Consumption and Real Income on Ecological Footprint Nexus in France

    • Authors: Marymagdaline Enowmbi Tarkang; Fetus Fatai Adedoyin, Festus Victor Bekun
      Abstract: Previously documented studies in the literature on how tourism leads to economic growth in the form of tourism-led growth hypotheses (TLGH) has been investigated. This study presents a new perspective on the growth of tourism by considering its impact on conventional energy consumption, real income level, and emission via the channel of globalization. Sequences of econometric tests were conducted to validate the hypothesized claims between tourism development and growth impact on conventional energy consumption and pollution proxy by ecological footprints, globalization GDP per capita, biocapacity, and tourists for the case of France. Empirical evidence from the Granger causality test presents a uni-directional causality from ecological footprints to GDP per capita and from biocapacity to ecological footprints. The correlation matrix shows interrelation amongst series with biocapacity significantly correlating with ecological footprints with tourist’s arrival having a positive correlation with ecological footprints and a negative one with biocapacity. GPD per capita was found to positively affect the ecological footprints and have a negative correlation with biocapacity and a significant relationship with tourists' arrivals. Additionally, globalization exerts a positive impact on ecological footprints, and its effect on biocapacity was found to be negative although globalization's effect on tourists’ arrivals and per capita GDP is significant. The ARDL estimation indicated biocapacity as a neutral agent for ecological footprints, tourist arrivals having a negative impact on ecological footprints, and globalization significantly affecting ecological footprints. From these findings, it is evident that tourism growth has a significant impact on energy consumption and pollution. Policy recommendations were also provided in this study accordingly. 
      PubDate: Sun, 01 Jan 2023 00:00:00 +000
  • Monitoring of Heat Flux Energy in the Northernmost Part of Sumatra Volcano
           Using Landsat 8 and Meteorological Data

    • Authors: Muhammad Yanis; Nasrullah Zaini, Isra Novari, Faisal Abdullah, Bondan Galih Dewanto, Muhammad Isa, Marwan Marwan, Muzakir Zainal, Abdurrahman Abdurrahman
      Abstract: Geothermal energy, as a part of green and renewable energy, has been widely developed in the world to replace the current conventional fossil energy. Peut Sagoe is an active volcano in the northern part of Sumatra. The volcanic mountain has not been completely explored for geothermal and energy reserves study. This is due to the volcano locates in a high topography and surrounded by dense tropical forest, which makes it challenging to deploy geophysical instruments in the area. The Landsat 8 thermal infrared and meteorological data from 2013 – 2020 were used to estimate the energy resources by calculating the radiative heat flux (RHF) and measuring the energy lost annually through the heat discharge rate (HDR). We also used the normalized differential vegetation index (NDVI) for vegetation analysis, and estimation of its emissivity data. The mono-window algorithm was used to calculate the land surface temperature (LST). The Stefan–Boltzmann equation was utilized to analyze thermal infrared data for RHF, and ambient temperature and relative humidity data were acquired from the Indonesian Meteorological Agency (BMKG) database. The results showed that low vegetation values and high LST of 25°C–35°C were found in crater areas, which indicate the underground thermal activities of the mountain. It demonstrates that the maximum RHF values were 55 W/m2 in 2013 and 37 W/m2 in 2020. The HDR data were calculated by applying 15% of the RHF data, and the amounts of energy lost were 132.5 MWe and 64.5 MWe in 2013 and 2015 respectively. It increased to 186.4 MWe in 2017 and 89 MWe in 2020. Based on these predicted results, we conclude that the combination of thermal infrared imagery of Landsat 8 and meteorological data is an effective approach in estimating geothermal energy potential and energy loss of volcanoes situated in remote areas
      PubDate: Sun, 01 Jan 2023 00:00:00 +000
  • Experimental Evaluation of Thermohydraulic Performance of Tubular Solar
           Air Heater

    • Authors: Yousif Fateh Midhat; Issam Mohammed Ali Aljubury
      Abstract: The thermohydraulic performance of a new design solar air heater (SAH) design was examined experimentally in this paper as a trial to improve the flat-plate SAH’s efficiency. A flat-plate solar air heater (FPSAH) and a jacketed tubular solar air heater (JTSAH) having similar dimensions were constructed to compare their thermal performance efficiencies. A band of Aluminum jacketed tubes   were arranged side by side in parallel to the airflow direction to form the absorber of a jacketed tubular solar air heater (JTSAH). The experiments were accomplished at three mass flow rates (MFR)s: 0.011 kg/s. 0.033 kg/s, and 0.055 kg/s. Results revealed that the maximum temperature difference was obtained from JTSAH at 38°C in comparison to 32°C from the FPSAH at MFR of 0.011 kg/s. The thermal losses from the upper glass cover of the JTSAH were less than the same losses at the FPSAH due to the reduced absorber and glass temperatures of the JTSAH. The gained power  was higher at the JTSAH than the FPSAH. At the JTSAH, at 0.055 kg/s MFR, the maximum average thermal efficiency obtained was 81%, and the maximum average thermos-hydraulic efficiency obtained was 75.61 %. It is noted that increasing the MFR increases the thermal efficiency, also, its optimum value rises the thermos-hydraulic efficiency to a specific optimum point. The pressure drop increases with the MFR and JTSAH compared to the FPSAH
      PubDate: Sun, 01 Jan 2023 00:00:00 +000
  • Techno-Economic Assessment of a 100 kWp Solar Rooftop PV System for Five
           Hospitals in Central Southern Thailand

    • Authors: Rawit Khamharnphol; Ismail Kamdar, Jompob Waewsak, Somphol Chiwamongkhonkarn, Sakrapee Khunpetcha, Chuleerat Kongruang, Yves Gagnon
      Abstract: This paper presents a techno-economic assessment of a 100 kWp solar rooftop photovoltaic (PV) system at five hospitals in central southern Thailand.  The system encompasses 100 kWp PV panels, 100 kW grid-tied inverters and balance of system (BOS) under the grid code of the Provincial Electricity Authority (PEA).  The latest PV technology of bifacial mono-crystalline solar panels, inverters and BOS were simulated along with the Meteonorm 7.3 database using the PVsyst simulation toolkit with different tilt angles, orientations, solar radiations and ambient temperature.  The technical aspects of solar rooftop PV power generation systems include the annual energy output and the performance ratio (PR) under IEC standard.  Further, an economic analysis of the model was examined using a cost benefit analysis (CBA) and various assumptions.  Four main financial criteria, i.e., benefit cost ratio (BCR), net present value (NPV), internal rate of return (IRR), and payback period (PBP) were evaluated under three different scenarios: (1) self-consumption scheme, (2) feed-in tariff (FiT) scheme, and (3) private power purchase agreement (PPA) scheme.  Finally, the levelized cost of energy (LCOE) was also calculated.  The results reveal that the Takua Thung hospital is characterized by the maximum average global horizontal irradiation (GHI) and the maximum annual produced energy of 199 kWh/m2 and 164.8 MWh/year, respectively.  The PR calculated for all hospital sites is above 85%. The outcomes of the financial analysis show that the optimum scenarios are PPA and FiT schemes.  The LCOE analysed in this study indicates that the Takua Thung hospital site has the lowest LCOE at 2.47 THB/kWh (0.07 USD/kWh).  This research confirms the potential for hospitals and stakeholders in central southern Thailand for investments in solar rooftop PV systems
      PubDate: Sun, 01 Jan 2023 00:00:00 +000
  • Consistent Regime-Switching Lasso Model of the Biomass Proximate Analysis
           Higher Heating Value

    • Authors: Akara Kijkarncharoensin; Supachate Innet
      Abstract: Prediction accuracy is crucial for higher heating value (HHV) models to promote renewable biomass energy, especially its consistency is crucial when retraining data and knowledge of the range are unavailable. Current HHV models lack consistency in accuracy and interpretability due to various reasons. Thus, this study aimed to construct an interpretable and consistent proximate-based biomass HHV model on a wide-range dataset. The model, regime-lasso, integrated the concepts of regime-switching, lasso regression, and federated averaging to construct a consistent HHV model. The regime-switching partitioned the dataset into optimal regimes, and the lasso trained the regime models. The regime-lasso model is a collection of these models. It provided root  mean square error of 0.4430– 0.9050, mean absolute error of 0.2743–0.6867, and average absolute error of 1.512–4.5894% in the literature’s wide-range datasets. The Kruskal–Wallis test confirmed the in-sample performance consistency at α=0.05, regardless of the training sets. In the out-of-sample situations without retraining, the model preserved its accuracy in six out of 11 datasets at α = 0.01. The interpretability of regime-lasso indicated the regime characteristic to be a factor of inconsistent prediction. The increase in FC had the maximum positive impact on HHV in the 2nd and 3rd regimes, while the increase in ASH negatively impacted the 1st and 2nd regimes. VM variation had neutral effects in all regimes. The regime-lasso solves the issues of accuracy declination and addresses the challenges in sensitivity analysis of the HHV model. The prediction accuracy issues of the model’s direct implementation were fixed.
      PubDate: Sun, 01 Jan 2023 00:00:00 +000
  • Optimization and Analysis of a Low-Pressure Water Scrubbing Biogas
           Upgrading System via the Taguchi and Response Surface Methodology

    • Authors: Gad Reuben Mugagga; Isaiah Bosire Omosa, Thomas Thoruwa
      Abstract: Biogas upgrading is essential in order to increase the calorific value and improve the quality of raw biogas. This present study aims at investigating the optimum performance of a near atmospheric pressure water scrubbing (NAPWS) system for biogas upgrading while using both the adsorption and absorption techniques. This was achieved through a two-stage process: namely, the Taguchi approach followed by the response surface methodology (RSM). The Taguchi orthogonal array design consisted of 27 runs where the raw biogas pressure (10 - 30 kPa), liquid flow rates (2.6 - 4.2 l/ min.) and variations of the steel wool height (0 - 45.72 cm) in the adsorption column were experimentally studied with respect to the methane (CH4) yield and removal efficiency of hydrogen sulfide (H2S) and carbon dioxide (CO2). From the experiments, the removal efficiency of hydrogen sulfide was greater than 87% with the average bio-methane content of 77.67%. During the second-stage, the analysis of variance (ANOVA) and the RSM were undertaken for optimization of the process parameters. The optimum bio-methane concentration of 84.71 (%v/v) CH4 and 13.31 (%v/v) CO2 was attained at gas pressure of 14kPa, liquid flow rate of 4.2 l/min., and steel wool height at 22.86cm obtained through numerical optimization. These results revealed that the utilization of the Taguchi and the RSM yielded to the best optimal system performance with the liquid flow rate as the most significant factor
      PubDate: Sun, 01 Jan 2023 00:00:00 +000
  • An Effect of Wind Veer on Wind Turbine Performance

    • Authors: Undarmaa Tumenbayar; Kyungnam Ko
      Abstract: An investigation was performed to identify the wind veer impact on wind turbine power performance at a wind farm located on Jeju Island, South Korea. A 2 MW wind turbine was used as a test turbine. An 80 m-tall met mast was located 220 m away from the test wind turbine and a ground lidar was installed close to the met mast. The wind veer conditions were divided into four types: veering in upper and lower rotor (VV), veering in upper and backing in lower rotor (VB), backing in upper and lower rotor (BB) and backing in upper and veering in lower rotor (BV). The frequency of the four types was identified at the wind farm. The characteristics of wind veer was analysed in terms of diurnal variation and wind speed. In addition, the power curves of the four types were compared with that under no veer condition. Also, the power deviation coefficient (PDC) derived from the power outputs was calculated to identify the effect of the four types on the turbine power performance. As a result, the frequencies of the types, VV, VB, BB and BV were 62.7 %, 4.9 %, 9.2 % and 23.1 %, respectively. The PDCs for the types VV and BV were 3.0 % and 4.2 %, respectively, meaning a power gain while those for the types VB and BB were -2.9 % and -3.9 %, respectively, meaning a power loss.
      PubDate: Sun, 01 Jan 2023 00:00:00 +000
  • Effects of Injection Strategies on Mixture Formation and Combustion in a
           Spark-Ignition Engine Fueled with Syngas-Biogas-Hydrogen

    • Authors: Thanh Xuan Nguyen-Thi; Thi Minh Tu Bui
      Abstract: The paper presents the effects of blend injection and dual injection strategies on mixture formation and combustion of syngas-biogas-hydrogen fueling engine working in the solar-biomass hybrid renewable energy system. The research was performed by simulation method on a retrofitted Honda GX200 spark-ignition engine. The results show that at the end of the compression process, in the case of blend injection of 50% syngas-50% biogas, the fuel-rich zone was positioned on the top of the combustion chamber, whereas in the case of dual injection, this zone was found on the top of the piston. In the case of 50% syngas-50% hydrogen supplied, at the end of the compression process, the fuel-rich area observed on the top of the piston with slightly deflected towards the inlet port in both cases of blend and dual injection. When shifting from blend injection mode to dual injection mode, in the case of 50% syngas-50% biogas fueling engine, the mean temperature of the exhaust gas decreased from 1208 K to 1161 K and the NOx concentration decreased from 1919 ppm to 1288 ppm. In the case of a 50% syngas-50% hydrogen fueling engine, the mean exhaust gas temperature decreases from 1283 K to 1187 K leading to a decrease in NOx concentration from 3268 ppm to 2231 ppm. The dual injection has the advantage of lower NOx emission, whereas the blend injection has the advantage of higher efficiency
      PubDate: Sun, 01 Jan 2023 00:00:00 +000
  • Statistical Analysis on The Near-Wake Region of RANS Turbulence Closure
           Models for Vertical Axis Tidal Turbine

    • Authors: Muhammad Wafiuddin Abd Rahim; Anas Abdul Rahman, Ayu Abdul-Rahman, Muhammad Izham Ismail, Mohd Shukry Abdul Majid, Nasrul Amri Mohd Amin
      Abstract: The flow field in the near wake region (up to six turbine diameters downstream) of a tidal current turbine is strongly driven by the combined wake of the device support structure and the rotor. Accurate characterisation of the near-wake region is important, but it is dominated by highly turbulent, slow-moving fluid. At present, limited number of research has been undertaken into the characterisation of the near-wake region for a Vertical Axis Tidal Turbine (VATT) device using the Reynolds Averaged Navier Stokes (RANS) model in the shallow water environment of Malaysia. This paper presents a comprehensive statistical analysis using the Mean Absolute Error (MEA), Mean Squared Error (MSE) and Root Mean Squared Error (RMSE) on the near-wake region for shallow water application by comparing numerical solutions (i.e., different types of RANS turbulence models using Ansys Fluent) with published experimental data. Seven RANS turbulence models with a single VATT, represented by using a cylindrical object, were employed in the preliminary study. The statistical analysis performed in this study is essential in exploring and giving a detailed understanding on the most suitable RANS turbulence model to be improved, specifically on its near-wake region. In this study, the near wake region is defined as D ≤ 6, where D is the device diameter. The analysis shows that the RANS numerical solutions are unable to accurately replicate the near-wake region based on large statistical errors computed. The average RMSE of near-wake region at z/D = [2, 3, 4, 6] are 0.5864, 0.4127, 0.4344 and 0.3577 while the average RMSE at far-wake region z/D = [8, 12] are 0.2269 and 0.1590, where z is the distance from the cylindrical object along the length of domain. The statistical error values are found to decrease with increasing downstream distance from a cylindrical object. Notably, the standard k–ε and realizable k–ε models are the two best turbulent models representing the near-wake region in RANS modelling, yielding the lowest statistical errors (RMSE at z/D = [2, 3, 4, 6] are 0.5666, 0.4020, 0.4113 and 0.3455) among the tested parameters
      PubDate: Sun, 01 Jan 2023 00:00:00 +000
  • An Improvement of Catalytic Converter Activity Using Copper Coated
           Activated Carbon Derived from Banana Peel

    • Authors: Abdul Hamid; Misbakhul Fatah, Wahyu Budi Utomo, Ike Dayi Febriana, Zeni Rahmawati, Annafiyah Annafiyah, Aurista Miftahatul Ilmah
      Abstract: The emission of nitrogen oxide (NOx), nitrogen monoxide (NO) and carbon monoxide (CO) from vehicle exhaust gas generates an adverse effect to the environment as well as the human health. Therefore, the need to reduce such emission is urgent. The decrease of the emission can be achieved through the use of catalytic converter. This study explains the application of catalytic converter prepared from activated carbon to enhance the activity through its adsorption ability. The activated carbon was derived from banana peels after heating them up at 400 ºC for 1.5 hours and activation using natrium hydroxide (NaOH). Several techniques including N2 adsorption-desorption, X-Ray Diffraction (XRD), Scanning Electron Microscopy-Electron Dispersive X-ray (SEM-EDX), and Fourier Transform Infrared (FTIR) were adopted to characterize the activated carbon properties. The activated carbon formed was then coated with copper. The activity of the catalytic converter using activated carbon coated with copper was then tested for its performance on diesel engine Yanmar TF 70 LY-DI with variations in the number of catalyst layers, namely 1 layer (C1), 2 layers (C2) and 3 layers (C3). Sample with three layers (C3) of catalyst exhibited the highest activity with the percentage efficiency in reducing emissions concentration of 48.76 %; 31.27 % and 29.35 % for NOx, NO and CO, respectively.
      PubDate: Sun, 01 Jan 2023 00:00:00 +000
  • Numerical Analysis of Transfer of Heat by Forced Convection in a Wavy

    • Authors: Naseer Abboodi Madlool; Mohammed J Alshukri, Ammar I Alsabery, Adel A Eidan, Ishak Hashim
      Abstract: Convective heat transfer of laminar forced convection in a wavy channel is studied in this paper. Numerical simulations of the 3D steady flow of Newtonian fluid and heat transfer characteristics are obtained by the finite element method. The effects of the Reynolds number (10 ≤Re≤1000), number of oscillations (0 ≤N≤5) and amplitude of the wall (0.05 ≤A≤0.2) on the heat transfer have been analyzed. The results show that the average Nusselt number is elevated as the Reynolds number is raised, showing high intensity of heat transfer, as a result of the intensified effects of the inertial and zones of recirculation close to the hot wavy wall. The rate of heat transfer increases about 0.28% with the rise of the number of oscillations. In the transfer of heat along a wavy surface, the number of oscillations and the wave amplitude are important factors. With an increment in the number of oscillations, the maximal value of the average velocity is elevated, and its minimal value occurs when the channel walls are straight. The impact of the wall amplitude on the average Nusselt number and dimensionless temperature tends to be stronger compared to the impact of the number of oscillations. An increase of the wall amplitude improves the rate of heat transfer about 0.91% when the Reynolds number is equal 100. In addition, when the Reynolds number is equal 500, the rate of heat transfer grows about 1.1% with the rising of the wall amplitude.
      PubDate: Sun, 01 Jan 2023 00:00:00 +000
  • The Conductivity Enhancement of 1.5Li2O-P2O5 Solid Electrolytes by
           Montmorillonite Addition

    • Authors: Yustinus Purwamargapratala; Anne Zulfia Syahrial, Teguh Yulius Surya Panca Putra, Evvy Kartini, Heri Jodi
      Abstract: Most solid electrolyte materials have not shown enough conductivity to be used as an electrolyte for a battery in electronic devices. The mixture of 1.5 Li2O and P2O5 has been reported to show a good conductivity higher than that of Li3PO4, which is thought to be due to phase mixtures that are formed during manufacturing process. Montmorillonite (MMT) was used to explore the effect of phase mixture on conductivity of new 1.5Li2O-P2O5-MMT solid electrolyte composite, which was prepared through conventional solid-state reaction procedures. This study was conducted, how the addition of MMT affects process of forming 1.5Li2O-P2O5-MMT compound, and whether it influences electrical properties and permittivity of compound. Morphology, hygroscopicity, and electrochemical characteristics of this material were analyzed in this study. The shape of glassy-like flakes was reduced in micrographs, and granular lumps were getting larger as MMT was added. Addition also tended to reduce hygroscopicity, as indicated by a reduced rate of porous absorption. Whole Nyquist plot consisted of only one imperfect semicircular arc, indicating only one relaxation process occurred in materials. Capacitance of all arcs indicated main contribution of response was from bulk material. Slope of dielectric loss of samples indicated that conduction in the samples was mainly dominated by dc conduction. MMT clays acted as a medium that absorbed liquid phase in solid-state reaction, increasing formation of dominant phase, which determined total conductivity of compound. Conductivity was higher than that of Li4P2O7, where the sample of 20 wt% MMT addition was most polarizable and most dielectric compound.
      PubDate: Sun, 01 Jan 2023 00:00:00 +000
  • An investigation of the Steady-State and Fatigue Problems of a Small Wind
           Turbine Blade Based on the Interactive Design Approach

    • Authors: Khalil Deghoum; Mohammed T Gherbi, Muhsin J Jweeg, Hakim S Sultan, Azher M Abed, Oday I Abdullah, Necib Djilani
      Abstract: A wind turbine blade is an essential system of wind energy production. During the operation of the blade, it is subjected to loads resulting from the impact of the wind on the surface of the blade. This leads to appear large deflections and high fatigue stresses in the structure of blades. In this paper, a 5 kW horizontal axis wind turbine blade model is designed and optimized using a new MATLAB code based on blade element momentum (BEM) theory.The aerodynamic shape of the blade has been improved compared with the initial design, the wind turbine power has been increased by 7% and the power coefficient has been increased by 8%.  The finite Element Method was used to calculate the loads applied to the blade based on Computational Fluid Dynamics (CFD) and BEM theory.High agreements were obtained between the results of both approaches (CFD and BEM).The ANSYS software was also used to simulate and optimize the structure of the blade by applying variable static loads 3.3, 6, and 8.3 kg and compared the results with the experimental results. It was reduced the maximum deflectionswith 37%, 42.85%, and 42.61% when using CFRP material and 4.5%, 15.45%, and 16.19% for GFRP material that corresponds to the applied forces. Based on the results, the mass of the optimized model decreased by 47.86% for GFRP and 71.24% for CFRP. IEC 61400.2 standard was used to estimate thefatigue loads, damage, blade life prediction, and verify blade safety usinga Simplified Load Model(SLM) and FAST software. It was found that the blade will be safe under extreme wind loads, and the lifetime of the wind blade (GFRP) is 5.5 years and 10.25 years,according to SLM and FAST software, respectively. At the same time, the lifetime of the wind blade (CFRP)is more than 20 years, according to the two applied methods.
      PubDate: Sun, 01 Jan 2023 00:00:00 +000
  • The Role of Membrane, Feed Characteristic and Process Parameters on RED
           Power Generation

    • Authors: Heru Susanto; Meike Fitrianingtyas, I Nyoman Widiasa, Titik Istirokhatun, Yunita Fahni, Assalaam Umar Abdurahman
      Abstract: Reverse electrodialysis (RED) is a renewable energy-generating SGE technique using energy from salinity gradients. This research investigates the effect of membrane and feed characteristics on reverse electrodialysis (RED) power generation. Some investigations on the process parameters effect for the complement of the main study were also conducted. The generated power of RED was measured using power density analysis. The experiments were performed using artificial seawater varied from 0 to 1 g/L NaCl for diluted salt water and from 0 to 40 g/L NaCl for concentrated salt water. In a study of ions type, NaCl non-pa is used to represent monovalent ions, and MgSO4 represents divalent ions. The results showed that the highest voltage generation is 2.004 volts by 14 cells number of the RED membrane utilizing a RED self-made laboratory scale. The power density was enhanced by raising the flow rate (0.10 L/min), concentration difference (40 g/L), and the presence of electrode rinse solution. Further, the ion type (monovalent, divalent, and multivalent) influenced the resulting RED power density, where the divalent ion (MgSO4) 's power density was greater than that of the monovalent ion (NaCl). The resistance and selectivity of the membrane were the major keys for the power generation of RED
      PubDate: Sun, 01 Jan 2023 00:00:00 +000
  • Effect of Pretreatment and C/N Ratio in Anaerobic Digestion on Biogas
           Production from Coffee Grounds and Rice Husk Mixtures

    • Authors: Budiyono Budiyono; Hashfi Hawali Abdul Matin, Ihzani Yulistra Yasmin, Iwang Septo Priogo
      Abstract: Indonesia has great potential in producing large quantities of renewable energy sources, such as biomass. Biogas is a renewable energy source produced from biomass. It is can be developed in agricultural countries producing rice and coffee, where a large amount of waste is produced in the form of rice husks and coffee grounds. This study examined the effect of physiochemical pretreatment and the C/N ratio on biogas production using coffee grounds and rice husk mixtures. Physical pretreatment was conducted by grinding the mixture up to 50 mesh size, followed by chemical pretreatment by soaking the mixture in 3% KOH; moreover, the variation in the C/N ratio was set at 25 and 30. Anaerobic bacteria were acquired from rumen fluid. The ratio of the coffee ground material, rice husks, and rumen fluid was 1:1:1. This research was conducted in duplicate under batch conditions at ambient temperature (25–35 oC) with a digester volume of 1.5 L. Biogas productivity was measured every 2 d for 60 d. The experimental results indicated that biogas production with a C/N ratio of 30 was 13.3–66.5% higher than that with a C/N ratio of 25. The inclusion of physical pretreatment at a C/N ratio of 30 increased biogas production by up to 31.3%. Moreover, the inclusion of a chemical pretreatment at a C/N ratio of 30 resulted in 30.3% higher biogas production. The kinetics model of biogas production showed that a C/N ratio of 30 with physical and alkaline pretreatment can produce maximum biogas yields of 6,619 mL and 6,570 mL, respectively. Overall, both pretreatments sequentially increased the biogas production significantly.
      PubDate: Sun, 01 Jan 2023 00:00:00 +000
  • The Various Designs of Storage Solar Collectors: A Review

    • Authors: Omer K Ahmed; Sameer Algburi, Raid W. Daouda, Hawazen N Shubat, Enas F Aziz
      Abstract: The use of solar energy to heat water is the more critical application of solar energy. Researchers are trying to develop different methods to improve the efficiency of solar water heaters to meet the increasing demand for hot water due to global population growth. To reduce the cost and increase the efficiency of solar heaters, the solar collector and the storage tank are combined into one part, and this system is called solar storage collector. It can be defined as geometric shapes filled with water, painted black, and placed under the influence of sunlight to gain the largest amount of solar energy. This article presents the various designs of solar storage collector. This review showed that design variables and design shape significantly affect the efficiency of the solar heating system. Climate and operational factors also have a strong influence on the performance of solar heating. Furthermore, scientists and researchers have also used nanotechnology, solar cells, and mirrors to improve other stored solar collectors' performance. Finally, recently published articles indicate an increase in interest in improving the efficiency of solar storage collector by creating new designs that enhance the economic and practical viability.
      PubDate: Sun, 01 Jan 2023 00:00:00 +000
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Heriot-Watt University
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