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.
Advanced Energy Technologies
Shima Sharifi; Rahbar Rahimi; Davod Mohebbi-Kalhori; Can Ozgur Colpan
Abstract
The power density of a direct methanol fuel cell (DMFC) stack as a function of temperature, methanol concentration, oxygen flow rate, and methanol flow rate was studied using a response surface methodology (RSM) to maximize the power density. The operating variables investigated experimentally include ...
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The power density of a direct methanol fuel cell (DMFC) stack as a function of temperature, methanol concentration, oxygen flow rate, and methanol flow rate was studied using a response surface methodology (RSM) to maximize the power density. The operating variables investigated experimentally include temperature (50-75 °C), methanol concentration (0.5-2 M), methanol flow rate (15-30 ml min-1), and oxygen flow rate (900-1800 ml min-1). A new design of the central composite design (CCD) for a wide range of operating variables that optimize the power density was obtained using a quadratic model. The optimum conditions that yield the highest maximum power density of 86.45 mW cm-2 were provided using 3-cell stack at a fuel cell temperature of 75 °C with a methanol flow rate of 30 ml min-1, a methanol concentration of 0.5 M, and an oxygen flow rate of 1800 ml min-1. Results showed that the power density of DMFC increased with an increase in the temperature and methanol flow rate. The experimental data were in good agreement with the model predictions, demonstrating that the regression model was useful in optimizing maximum power density from the independent operating variables of the fuel cell stack.
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.
