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Öğe Comparison of different cooling options for photovoltaic applications(Institute of Electrical and Electronics Engineers Inc., 2018) Ökkul, F.B.; Kayabasi, E.; Çelik, E.; Kurt, H.; Arcaklioglu, E.A temperature increase plays a negative role on photovoltaic (PV) panel conversion efficiency by increasing recombination rates. In this study, air- and water-cooling options were simulated to investigate the efficiency behavior of a specific PV panel made of heterojunction Silicon (Si) whilst PV panel was cooling in operation by using ANSYS-FLUENT. For air cooling, two different options were suggested: air cooling with four different flow speeds and air cooling with a heat sink addition with three different flow speeds. As for water-cooling three flowrates were considered. Temperature distributions of PV panels for the all cooling options were demonstrated as a function of flow velocity of air and flowrate of water for different cooling conditions and compared with each other. The influence of temperature difference on panel conversion efficiency were also discussed. As a result, heat sink with a proper flow arrangement cooling option showed the best performance in terms of minimum material, minimum cost and minimum complexity with the 42 °C, 38.4 °C, 35.9°C average surface temperatures and 20.9%, 21.3%, 21.5% panel efficiencies. © 2018 IEEE.Öğe Design and simulation of a microchannel heat exchanger for cooling a micro processor using ethylene(TUBITAK, 2021) Tom, B.; Kayabasi, E.In this study, a microchannel heat exchanger was proposed instead of a conventional air-cooled heat sink in order to obtain uniform surface temperature distribution. In addition, flow and heat transfer simulations were performed using Flo-EFD software. First, the temperature distribution of the air domain and microprocessor in the computer case was obtained. Afterward, the system with the proposed microchannel heat exchanger was subjected to the same processes, and the results were compared. As a result of the study, it was revealed that the microchannel heat exchanger reduced the processor temperature between 54-55 °C and 18-19 °C. It has also been observed that removing the heat sink allows the air drawn from the outside environment to circulate more efficiently around other heat-generating elements in the computer case. Hence, a more homogeneous and lower temperature distribution within the computer case was obtained. © 2021, TUBITAK. All rights reserved.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 Investigating the effects of cooling options on photovoltaic panel efficiency: State of the art and future plan(Institute of Electrical and Electronics Engineers Inc., 2018) Özkul, F.B.; Kayabasi, E.; Çelik, E.; Kurt, H.; Arcaklioglu, E.Currently, cooling of photovoltaic (PV) panels, a significant issue due the negative effect on panel efficiency, is subjected to intensive researches. For this purpose, numerous researches on cooling methods are performed to keep the panel efficiencies around the design values. In this study, a comprehensive literature review was presented to give the status of the technological improvement in cooling options. In addition, strong and weak aspects of the studies were discussed, and advantageous methods were emphasized for the further application of PV panels. Finally, future perspective of PV panel cooling studies was explored with proper cooling options in lower operating temperatures for higher operation efficiencies. © 2018 IEEE.Öğe Simulation of heat exchangers and heat exchanger networks with an economic aspect(Elsevier - Division Reed Elsevier India Pvt Ltd, 2018) Kayabasi, E.; Kurt, H.Relations between effectiveness (epsilon) and expense coefficients (zeta) were derived, and an economic simulation model was developed to simulate heat exchangers (HE) and HE networks (HEN) in all flow types for the first time. epsilon values of parallel flow, counter flow, cross flow and all HEs under the condition of C-r = 0 were derived in terms of zeta, NTU (Number of Transfer Unit) and minimum heat capacities (C-min). epsilon values obtained from economic calculations were used for developing economic simulation model of HEs. Vectors including outlet temperatures and inlet temperatures of flows were obtained from static simulation to utilize in economic simulation model. Then, case studies were performed with counter flow HE and epsilon values randomly determined in a sample HEN. Use (N), expense (P) and savings (E) of all HEs in a HEN were calculated easily by the way of linear equation systems without any complex processes, iterations, software and special hardware, in terms of both cold and hot flows properties by using economic simulation model. (C) 2018 Karabuk University. Publishing services by Elsevier B.V.
