Renewable Energy Resources and Technologies
Ali Ebadi; Ali Akbar Abdoos; Mohammad Ebrahim Moazzen; Sayyed Asghar Gholamian
Abstract
Nowadays, the Permanent Magnet (PM) generator has become an instrumental tool for wind power generation due to its high performance. In this study, an optimal design is established to provide a cost-effective multiphase outer-rotor PM wind generator (OR-PMWG). The cost of the generation system (generator ...
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Nowadays, the Permanent Magnet (PM) generator has become an instrumental tool for wind power generation due to its high performance. In this study, an optimal design is established to provide a cost-effective multiphase outer-rotor PM wind generator (OR-PMWG). The cost of the generation system (generator and power converter) as well as the annual energy output must be optimized to ensure cost-effective PM wind generation. In fact, the main novelty of this paper lies in the presentation of an accurate model of OR-PMWG and the investigation of the design variables affecting annual energy output and the generation system cost (GSC). In this respect, a multi-objective framework is presented to make satisfactory agreement among all objectives. At first, the main optimal design objectives namely generation system cost and annual energy output are optimized separately and then, a multi-objective optimization is established, in which all the objectives are considered simultaneously. In order to tackle these optimization problems, Genetic Algorithm (GA) is adopted herein to determine the design variables. It is also shown that simultaneous optimization with 71.39 (MWh) AEO and 2651.51 (US$) GSC leads to a more optimal design for a PM wind generation system. In addition, the effectiveness of the presented optimal design is demonstrated by making a comparison between a prototype outer-rotor PM wind generator and the theoretical counterpart. Finally, a finite element analysis (FEA) is carried out for the validation of the outcomes obtained from the proposed optimal design.
Renewable Energy Resources and Technologies
Rasoul Aydram; Hossein Haji Agha Alizade; Majid Rasouli; Behdad Shadidi
Abstract
Reduced emissions of greenhouse gases and global warming can be made possible by discovering alternative energies and reduced dependence on fossil fuels. Biogas is considered as one of the alternatives to fossil fuels. This study investigates anaerobic co-digestion for the development of biogas with ...
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Reduced emissions of greenhouse gases and global warming can be made possible by discovering alternative energies and reduced dependence on fossil fuels. Biogas is considered as one of the alternatives to fossil fuels. This study investigates anaerobic co-digestion for the development of biogas with sheep blood and cheese whey. Digested cow manure was used as inoculum. Using the Design Expert 10 program and within the context of mixture design, the experiments were designed. Then, 22 experimental digesters with a volume of 500 mL were considered for doing the experiments considering the design output provided by the software. Each one was filled with 300 mL of different compositions of three matters. The digesters were kept in the mesophilic temperature range (37 °C ) for 21 days. Biogas was measured using the BMP test on a daily basis. According to the experimental findings, the best composition included 35 % sheep blood, 35 % cheese whey, and 30 % inoculum. This biogas composition produced a biogas yield of 146.66 mL/g vs. The amount of methane production in this compound was 73.33 mL/g vs. After modeling, the Design Expert software predicted an optimal composition including 44 % sheep blood, 24 % cheese whey, and 32 % inoculum. Biogas yield of this prediction was 143 mL/g vs. The findings show that in order to overcome acidification in digestion of matters such as cheese whey, a composition of matters with higher pH stability can be used to increase the amount of biogas and methane produced in a particular period. Furthermore, using inoculum accelerates the digestion operations due to existence of many microorganisms and saves time and energy.
Renewable Energy Resources and Technologies
Ramasamy Dhivagar; Murugesan Mohanraj
Abstract
In this experimental work, the energy efficiency and performance parameters of a coarse aggregate-assisted single-slope solar still were analyzed using Taguchi analysis. The preheated inlet saline water was sent to the solar still using thermal energy accumulated in coarse aggregate to enhance its productivity ...
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In this experimental work, the energy efficiency and performance parameters of a coarse aggregate-assisted single-slope solar still were analyzed using Taguchi analysis. The preheated inlet saline water was sent to the solar still using thermal energy accumulated in coarse aggregate to enhance its productivity and energy efficiency. The daily distillate of the proposed model was observed to be about 4.21 kg/m2 with the improved efficiency of around 32 %. Furthermore, the parameters that influenced the performance of the solar stills and their levels were identified using Taguchi analysis. The Signal to Noise (S/N) ratios of the coarse aggregate temperature, saline water temperature, glass temperature and energy efficiency were observed to be about 45.4 °C, 41.4 °C, 36.7 °C and 20.07 %, respectively. The results revealed that, the percentage difference between predicted and experimental values was observed to be about 1.6 %, 0.6 %, 1.5 % and 3.3 %, respectively. The optimization method confirmed that there was good agreement between the predicted and experimental values.
Advanced Energy Technologies
Fatemeh Boshagh; Khosrow Rostami
Abstract
The current review purpose is to present a general overview of different experimental design methods that are applied to investigate the effect of key factors on dark fermentation and are efficient in predicting the experimental data for biological hydrogen production. The methods of two levels full ...
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The current review purpose is to present a general overview of different experimental design methods that are applied to investigate the effect of key factors on dark fermentation and are efficient in predicting the experimental data for biological hydrogen production. The methods of two levels full and fractional factorials, Plackett–Burman, and Taguchi were employed for screening the most important factors in dark fermentation. The techniques of central composite, Box–Behnken, Taguchi, and one factor at a time for optimization of the dark fermentation were extensively used. Papers on the three levels full and fractional factorials, artificial neural network coupled with genetic algorithm, simplex, and D-optimal for the optimization of the dark fermentation are limited, and no paper on the Dohlert design has been reported to date. The artificial neural network coupled with genetic algorithm is a more suitable method than the RSM technique for the optimization of dark fermentation. Literature shows that the optimization of critical factors plays a significant role in dark fermentation and is useful to improve the hydrogen production rate and hydrogen yield.
Renewable Energy Resources and Technologies
Amir Reza Khedmati; Mohammad Behshad Shafii
Abstract
The humidification-dehumidification system is one of the desalination technologies that can utilize non-fossil thermal sources and requires insignificant input energy. This system is usually suitable for rural areas and places far from the main sources of energy. The purpose of this study is to obtain ...
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The humidification-dehumidification system is one of the desalination technologies that can utilize non-fossil thermal sources and requires insignificant input energy. This system is usually suitable for rural areas and places far from the main sources of energy. The purpose of this study is to obtain the most suitable working conditions and dimensions of this system. In this research, thermodynamic modeling was first performed for a simple type of the system (water-heated); then, the effect of parameters on the system performance was investigated. Modeling was conducted through a numerical simulation; furthermore, the assumption of the saturation of exhaust air from the humidifier was also considered in the mentioned code. Afterward, a comparison was made between two different forms of the system, and the proper form was chosen for the rest of the research. Moreover, through heat transfer equations, the dimensions of the two main parts of the system, i.e., humidifier and dehumidifier, were calculated. Besides, multi-objective optimization was carried out for two objective functions, i.e., gained output ratio (GOR) and the system volume, to reduce the space occupied by the system and reach the desired efficiency simultaneously. The optimization was performed using a simulation program, and results were obtained for different weights in order to optimize each objective function. For instance, 379 liters of freshwater can be produced in a day with a total volume of 48 liters for the humidifier and the dehumidifier in the optimized system.
Renewable Energy Resources and Technologies
Alireza Shirneshan; Mohammad Mostofi
Abstract
The determination of the optimum engine working conditions plays an important role in increasing engine performance and reducing exhaust emissions. The main objective of this study is to optimize the performance and emission characteristics of a CI engine fueled with aviation fuel-biodiesel-diesel blends ...
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The determination of the optimum engine working conditions plays an important role in increasing engine performance and reducing exhaust emissions. The main objective of this study is to optimize the performance and emission characteristics of a CI engine fueled with aviation fuel-biodiesel-diesel blends at various engine speeds and loads using Mixture-RSM. According to the experimental tests carried on a 4-cylinder engine, the mathematical models were developed. Then, the optimization processes were defined as the six scenarios containing the consideration of performance or emission parameters or both of them. Scenario 1 shows that the higher percentage of diesel and jet fuel can improve the performance parameters of the engine; however, Scenario 2 shows that only higher percentage of diesel can improve the engine emission due to negative effect of biodiesel on the NOx emissions and negative impact of aviation fuel on the CO and HC emissions that limit the amount of biodiesel and aviation fuel in the fuel mixture. The results also show that Scenario 3 does not vary compared to Scenario 2. The optimized point for both of engine performance and emission parameters presented in Scenario 6 was calculated as D48.9B32.7J18.4 at 2526 RPM and full engine load to obtain 88.4 (kW), 337 (N.m), 255 (gr/Kw.hr), 0.0268 (%), 469 (ppm), 7.7 (%) brake power, torque, BSFC, CO, NOx, and HC emission, respectively.
Advanced Energy Technologies
Ali Mostafaeipour; Mojtaba Qolipour; Hossein Goudarzi; Mehdi Jahangiri; Amir-Mohammad Golmohammadi; Mostafa Rezaei; Alireza Goli; Ladan Sadeghikhorami; Ali Sadeghi Sedeh; Seyad Rashid Khalifeh Soltani
Abstract
Fuel cells are potential candidates for storing energy in many applications; however, their implementation is limited due to poor efficiency and high initial and operating costs. The purpose of this research is to find the most influential fuel cell parameters by applying the adaptive neuro-fuzzy inference ...
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Fuel cells are potential candidates for storing energy in many applications; however, their implementation is limited due to poor efficiency and high initial and operating costs. The purpose of this research is to find the most influential fuel cell parameters by applying the adaptive neuro-fuzzy inference system (ANFIS). The ANFIS method is implemented to select highly influential parameters for proton exchange membrane (PEM) element of fuel cells. Seven effective input parameters are considered including four parameters of semi-empirical coefficients, parametric coefficient, equivalent contact resistance, and adjustable parameter. Parameters with higher influence are then identified. An optimal combination of the influential parameters is presented and discussed. The ANFIS models used for predicting the most influential parameters in the performance of fuel cells were performed by the well-known statistical indicators of the root-mean-squared error (RMSE) and coefficient of determination (R2). Conventional error statistical indicators, RMSE, r, and R2, were calculated. Values of R2 were calculated as of 1.000, 0.9769, and 0.9652 for three different scenarios, respectively. R2 values showed that the ANFIS could be properly used for yield prediction in this study
Renewable Energy Resources and Technologies
Ashkan Gholami; Aryan Tajik; Shahab Eslami; Majid Zandi
Abstract
The current study investigated the feasibility of renewable energy harvesting to meet the energy need of a dairy farm in Shahroud, Iran. Therefore, considering the available renewable resources including solar, wind, and biomass in the site and the electrical demand of the farm, the techno-economic and ...
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The current study investigated the feasibility of renewable energy harvesting to meet the energy need of a dairy farm in Shahroud, Iran. Therefore, considering the available renewable resources including solar, wind, and biomass in the site and the electrical demand of the farm, the techno-economic and environmental analyses were carried out. By using Homer software, the optimized system was selected. It was shown that although there was wind potential within the farm site, the most economical system would be a system consisting of a 100 kW biomass power plant and a 169 kW PV plant. Furthermore, by using RETScreen software, the economic and environmental analyses for the selected system were carried out. The simple and equity paybacks were 5.8 and 4.2 years for the proposed system, which confirmed the economic feasibility of the proposed system. Moreover, the gross annual GHG emission would be reduced by 91.5 %. The techno-economic and environmental analyses conducted in the current paper confirmed that the proposed system could be easily extended for other dairy farms, which resulted in a significant increase in the energy ratio of the dairy farms.
Renewable Energy Resources and Technologies
Negin Maftouni; Kiana Motaghedi
Abstract
Traditional fossil fuels, which are also depleting cause environmental problems. A significant portion of global energy consumption is due to building air conditioning systems. Nowadays, considerable attention is drawn to renewable and sustainable energy sources to support the energy requirements of ...
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Traditional fossil fuels, which are also depleting cause environmental problems. A significant portion of global energy consumption is due to building air conditioning systems. Nowadays, considerable attention is drawn to renewable and sustainable energy sources to support the energy requirements of buildings. In this study, a solar absorption chiller was designed for a three-floor residential building in hot and arid climate. At first, thermal loads in the building were calculated using Carrier software. The material and color of the exterior walls, as well as window types, were changed to reduce the heat transfer coefficient and get an optimum design. Results indicate that by using the optimum design, maximum heating load reduction and maximum cooling load reduction can be achieved with approximate rates of 37 % and 12 %, respectively. Considering safety factor and based on the maximum cooling load, a single-effect LiBr-water solar absorption chiller was designed for the optimum building. Two different scenarios were suggested using two types of flat plate and evacuated tube collector. Results show that in the case of evacuated tube collector the net collector area of 254.18 m2 is sufficient to supply the cooling power. Implementing flat plate collectors would result in occupying an area of 398.5 m2. Regarding the limitation of total area of roof and efficiency issues, the evacuated tube collector is the best option.
Mohammad Kord; Seyed Mojtaba Sadrameli; Barat Ghobadian
Abstract
The purpose of this research work was to investigate the optimum operating conditions for biodiesel production from castor oil using a microwave. The Box–Behnken design of experiment was carried out using the Design Expert 7. A response surface methodology (RSM) was used to analyze the influence ...
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The purpose of this research work was to investigate the optimum operating conditions for biodiesel production from castor oil using a microwave. The Box–Behnken design of experiment was carried out using the Design Expert 7. A response surface methodology (RSM) was used to analyze the influence of the process variables (molar ratio of methanol to castor oil, catalyst concentration, reaction time, and microwave power) on the biodiesel yield. Optimizing biodiesel production reaction based on the yield of reaction by means of response surface method showed that 1.44 wt.% of catalyst concentration, 7.12:1 molar ratio of alcohol to oil, microwave power of 500 W and 120 seconds of reaction time produces the best results for maximizing the conversion percent. Finally, Biodiesel samples were analyzed with Gas Chromatography (GC) method for determination of fatty acid methyl ester yield. The yield of reaction obtained was 92.15% with above operating conditions and temperature of output flow was 58 oC.
Mahboobe Sabaghian; Fateme Ahmadi Boyaghchi
Abstract
Energy, exergy and exergoeconomic (3E) evaluation are performed to assess the performance of a NH3/H2O cycle integrated with parabolic trough solar collectors (PTSC). To provide continuous electricity produced by generator when solar beam radiation is insufficient a stabilizer temperature subsystem is ...
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Energy, exergy and exergoeconomic (3E) evaluation are performed to assess the performance of a NH3/H2O cycle integrated with parabolic trough solar collectors (PTSC). To provide continuous electricity produced by generator when solar beam radiation is insufficient a stabilizer temperature subsystem is utilized. The major thermodynamic parameters and climate conditions variations are selected to investigate, for their effects on the energy efficiency, exergy efficiency and unit cost of electricity of the overall system. The results reveal that the solar collectors exhibit the worst exergy and exergoeconomic performance, so that when system is only fuelled by solar energy, elevation of solar beam irradiation around 40% reduces the efficiencies and electricity production cost within 23% and 0.4%, respectively. It is found that the increment of ammonia basic concentration, turbine inlet pressure, evaporator inlet temperature and evaporator pinch temperature lead to elevation of energy and exergy efficiencies and decrement of electricity production cost. Then, the single and multi-objective optimizations are performed to maximize the energy and exergy efficiencies and minimize the electricity production cost based on genetic algorithm (GA). Results indicate that the electricity production cost obtained through economic optimization is less than around 2% and 2.2% compared to the optimization based on the first and second laws of thermodynamics. Multi objective optimization causes reduction of electricity production cost around 14% and enhancement the energy and exergy efficiencies 8.5% and 6.7%, respectively too.
