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Öğe Artificial neural network approach for evaluation of temperature and density profiles of salt gradient solar pond(Elsevier Sci Ltd, 2007) Kurt, H.; Atik, K.; Ozkaymak, M.; Binark, A. K.The purpose of this study is to evaluate temperature and density profiles of an experimentally investigated salt gradient solar pond (SGSP) by using artificial neural network ( ANN). The input parameters of the ANN are solar pond depth, ambient temperature, radiation absorption coefficient of salty solution in the pond, initial density values of the pond and time of day. The output parameters of the ANN are temperature and density profiles in the pond. The experimental data set consists of 168 values. These divided into two groups, of which the 134 values were used for training/learning of the network and the rest of data ( 34 values) for testing/validation of the network performance. According to the ANN predicted results compared to the experimental results, the mean relative error (MRE) is 2.30% for temperature and 0.63% for density. The correlation coefficients (R-2) between the experimentally measured and the ANN predicted results are 0.9632 for temperature and 0.9855 for density in the test/validation data set. The calculated errors of proposed ANN model are in acceptable ranges. These results indicated that the ANN approach could be considered as an alternative and practical technique to evaluate the temperature and density profiles of a SGSP.Öğe BIOGAS PRODUCTION FROM ANIMAL MANURE(Taylors Univ Sdn Bhd, 2015) Recebli, Z.; Selimli, S.; Ozkaymak, M.; Gonc, O.An experimental study worked on a model biogas production unit which has 0.5 m(3) fermentation tank capacities of a breeding farm in the Urla district of Izmir/Turkey. The farm animal quantity is 70 cattle and 1400 chicken. Animal wastes (poultry manure and bovine animals manure) were anaerobically fermented in the tank. It is known in literature, the optimum fermentation occurs at 298-313 K temperatures. In this respect, experimentation was performed at summer season and average regional temperature was 307 K and so reaction does not require the extra heating for the optimization of process. Biogas production potential from bovine animal and poultry manure was separately studied. Firstly, 350 kg bovine animal manure blend (175 kg manure+ 175 kg water) filled to the tank and the process occurred. Secondly, 375 kg poultry manure blend (50 kg manure+ 325 kg water) was filled to the tank and the processes done. Then the biogas production rates was evaluated and compared for two processes. Results showed that daily 6.33 m(3) and 0.83 m(3) biogas productions were obtained from fermentation of bovine animal manure and poultry animal manure. Lower heating value of natural gas was known 34,000 kJ/m(3) and biogas LHV value was predicted 21,000 kJ/m3 by the 62% CH4 content. By using biogas as a fuel to the heating or energy systems instead of natural gas about 0.35 $/m(3) energy cost is saved.Öğe Biogas production from animal manure(Taylor's University, 2015) Recebli, Z.; Selimli, S.; Ozkaymak, M.; Gonc, O.An experimental study worked on a model biogas production unit which has 0.5 m3 fermentation tank capacities of a breeding farm in the Urla district of Izmir/Turkey. The farm animal quantity is 70 cattle and 1400 chicken. Animal wastes (poultry manure and bovine animals manure) were anaerobically fermented in the tank. It is known in literature, the optimum fermentation occurs at 298-313 K temperatures. In this respect, experimentation was performed at summer season and average regional temperature was 307 K and so reaction does not require the extra heating for the optimization of process. Biogas production potential from bovine animal and poultry manure was separately studied. Firstly, 350 kg bovine animal manure blend (175 kg manure+175 kg water) filled to the tank and the process occurred. Secondly, 375 kg poultry manure blend (50 kg manure+325 kg water) was filled to the tank and the processes done. Then the biogas production rates was evaluated and compared for two processes. Results showed that daily 6.33 m3 and 0.83 m3 biogas productions were obtained from fermentation of bovine animal manure and poultry animal manure. Lower heating value of natural gas was known 34,000 kJ/m3, and biogas LHV value was predicted 21,000 kJ/m3 by the 62% CH4 content. By using biogas as a fuel to the heating or energy systems instead of natural gas about 0.35 $/m3 energy cost is saved. © School of Engineering, Taylor’s University.Öğe Co-digestion of cattle manure and tea waste for biogas production(International Journal of Renewable Energy Research, 2018) Aksay, M.V.; Ozkaymak, M.; Calhan, R.The increase of world population brings energy and food requirements. Increasing energy demand drives humanity towards new energy sources and work towards energy efficiency developments. Concordantly, due to population growth, the amount of waste is also increasing and causing environmental -issues. Biogas production by co-digestion of wastes -could be a common solution to both issues. Animal manures are typically used as a main substrate in co-digestion applications. Tea waste is used as a co-substrate in this -work due to having large production and consumption volume in Turkey. The aim of this study is to emerge new methods for disposal and reuse of household tea waste. For this purpose, co-digestion method was carried out to determine the biogas potential of household tea waste. Laboratory scale batch type co-digestion is carried out for 80 days under mesophilic (37±2 °C) conditions. All reactors fed with different mixing ratio of wastes and operated with different stirring speeds. The results showed that co-digestion of the wastes have positive impact on biogas and methane yield. Optimum biogas yield is 296.89 mL/gVS and 77.10% methane content are obtained from A2 which consist of 75% cattle manure and 25% tea waste with 100 rpm stirring speed. According to the results, co-digestion of cattle manure and household tea waste both have a positive effect on biogas production and methane content of biogas. © 2018, International Journal of Renewable Energy Research.Öğe Design of hazelnut drying system supported by solar energy, investigation of drying performance and determination of proper drying model(International Journal of Renewable Energy Research, 2020) Acar, B.; Dagdeviren, A.; Ozkaymak, M.Rapid and efficient drying process for the hazelnuts is required because of the lack of plain areas for solar drying due to the rough landforms in the Black Sea Region, high amount of cloudy days, causing product deteriorations and rots by instantaneous rain transitions and unexpected sudden rains. In this study, a hazelnut drying system supported by solar energy in order to achieve a rapid and efficient drying process was designed and drying performance was examined. In the designed system, a spiral shaft was used for movements of the hazelnuts in the drying chamber. Besides, the inner temperature of the chamber increased with the help of a sun collector. The process control device was used to keep the inner temperature as constant at 40°C. In the experiments, 20kg weight hazelnut husk was used. The experiment was performed between 09:00 and 17:00 hours in a day with normal sunlight conditions and the total drying process took about 8 hours. The moisture ratios (MR) and drying rates (DR) graphics were obtained by scaling weight losses of the hazelnuts in each hour. As a result, it is observed that the 20kg weight of the hazelnuts decreased to the 17.201kg and therewith the total removed moisture from the hazelnuts was about 2.799kg. In the light of the moisture ratios obtained by experiments, 8 different kinetic drying models were performed with MATLAB software. According to the kinetic model results, the lowest reduced chi-square (?2) and root mean square error (RMSE) were about 241x10-6 and 155x10-4 respectively. In addition, the coefficient of determination (R2) was calculated as 0.9982 which is the highest result closest to 1. Among the 8 kinetic models, the Page model is given the best results for the drying process. © 2020 Institut za Arhitekturu i Urbanizam Srbije.Öğe Energy exergy efficiencies and environmental effects of mixed fuelled (solid plus gas) industrial facility steam boiler(Elsevier Sci Ltd, 2013) Kaya, D.; Eyidogan, M.; Ozkaymak, M.; Turhan, F.; Kilinc, E.; Kayabasi, E.; Sahin, Z.In this paper, an experimental study has been performed for mixed (solid + gas) fuelled boiler operating at 7000 kPa pressure and 778.15 K temperature with a nominal capacity of 25 kg s(-1) in order to find improvement in the boiler efficiency and to reduce its environmental emissions. In this scope, while the boiler was working under operating conditions, temperature, pressure, velocity, and combustion gas measurements were performed and the measured data were used to establish mass and energy balance. Main efficiency loses were identified as operation of the boiler with high excess air factor (39.78%), leakage air in the rotary air hater and surface thermal losses. Calculations, were performed with the use of measured data, estimated that the boiler and second law efficiency were calculated as 85.3 and 39.6% respectively. When the injected heat value on water is 67 433.65 kW in the boiler, by the reduction of excess air factor is 550 kW and by the prevention of leakage air is 1251.6 kW, including totally saving amount is 1801.7 kW. Financial value of this saving was calculated about 309 465$.Öğe Techno-economic Analysis of a More Efficient Hydrogen Generation System Prototype: A Case Study of PEM Electrolyzer with Cr-C Coated SS304 Bipolar Plates(Wiley-V C H Verlag Gmbh, 2019) Taner, T.; Naqvi, S. A. H.; Ozkaymak, M.This study presents a more efficient and innovative prototype of a hydrogen generation system using proton exchange membrane (PEM) electrolyzer. The aim of this study is to generate hydrogen gas energy that conducts the chemical reaction by electrolytic movements as well as to design a system that generates energy with H-2 through new technology. The Cr-C coated SS304 bipolar plates were used in the electrolysis cells and the septic mixture (urea, ammonia, methyl alcohol) was used in the electrolyzer as a chemical solution to make the hydrogen production more efficient and cost effective. The super strong magnets were also mounted on the outer surface of the electrolysis cells to improve the performance and efficiency. The performance of the electrolyzer was determined by operating the current and voltage parameters. The results were collected through experiments and the optimization of the different parameters. In this prototype study, the production of hydrogen gas in the system (1 MW) through the presented system was found to be as 6 m(3) h(-1) and the simple payback period (SPP) was calculated as 2.32 y. These results indicate that this system can produce hydrogen more efficiently and economically.Öğe Towards Evaluating the Performance of Vertical Axis Wind Turbine Consist of Slant Straight Blades(Institute of Electrical and Electronics Engineers Inc., 2020) Abusannuga, H.; Ozkaymak, M.In this theoretical study, the effect of variable blade inclination angle or angle of blade slant on power factor Cp of straight blades- vertical axis wind turbine has been studied. Where a slop of angle on the horizontal plane was changed from an angle of 25 degrees to an angle of 85 degrees with the amount of change is equal to 20 degrees. Within the scope of this research, the wind rotor was given the name 'straight-slant vertical axis wind turbine' (SS-VAWT). The mathematical model 'Multi Stream Tube' was applied in the form of a computer program by using 'Microsoft Visual Basic', with regard to checking the effectiveness of this program, it was done by comparing its theoretical results with previous laboratory results from another researches, as it proved its effectiveness in achieving satisfactory results that fit the aim of this study. This study was conducted on twelve configurations of SS-VAWT, which were divided into four groups which are (H group), (R group), (N group) and (C Group) to study the effect of blade inclination angle at different values of rotor height (H), rotor radius (R), rotor blades number (N) and blade airfoil length (C) respectively and separately. The results are expressed by power curves as a function of tip speed ratio. As the results indicated that angle of blade slant range from 45 degrees to 65 degrees is the best range for rotor blade inclination in terms of obtaining the highest power factor CpM in addition to the largest range of tip speed ratio and moreover the angle 45 degree has the advantage of limiting the problem of starting a self-motion. © 2020 IEEE.
