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Öğe Closed-loop aluminium oxide nanofluid cooled photovoltaic thermal collector energy and exergy analysis, an experimental study(Elsevier, 2022) Jasim, Othman Mohammed Jasim; Selimli, Selcuk; Dumrul, Hakan; Yilmaz, SezayiPV/T collector cooling was studied experimentally regarding the energy and exergy analysis by Al2O3 nanofluid circulation which is in two different flow patterns. A 20 W polycrystalline PV module was used as a comparison module. Identical PV modules were used for the construction of PV/T collectors, too. PV/T-A collector model was created with the PV module, a copper coil tube was the nanofluid circulated was placed to the backside of it. A PV/T-B collector was made up by placing the Al2O3 nanofluid circulating polyamide channel structure on the backside of the PV module. A 50 W monocrystalline PV module was used to supply power to the circulation pump and heat exchanger fans to provide energy independence from mains electricity. PV/T-A and PV/T-B collectors exposed to 792.83 W/m(2) solar radiation equivalent 121.3 W solar power were cooled 28.94% and 48.54% better regarding the PV module. Electrical power outputs are 5.8 W, 8.13 W, 10.34 W for the PV module, PV/T-A, and PV/T-B collectors. Electrical gaining from the PV/T-A and PV/T-B collectors increased 40.17% and 78.27% by cooling. Thermal gaining from PV/T-A and PV/T-B collectors are 42.8 W and 53.39 W. First and second law efficiencies were determined as 4.78%, 42%, 52.52%, and 5.01%, 7.35%, and 9.42% for PV module, PV/T-A, and PV/T-B collectors. Enhancement in solar utilization with PV/T-A and PV/T-B collectors are 45.13 W, and 57.93 W and proportionate equivalents to 37.2% and 47.75%. Enviro-economics size was estimated as 0.094 tCO(2)/year, and 0.121 tCO(2)/year carbon reduction and equivalent 1.41$ and 1.81$ carbon trade value.Öğe Design and Experimental Analysis of Heat Pipe Solar Collector Drying System(Gazi Univ, 2023) Dumrul, Hakan; Kaya, Edanur; Yilmaz, SezayiIndustrial and agricultural products can be dried using natural and technical methods. The energy spent to obtain the hot drying air constitutes the drying cost. In this stab. a heat recovery drying system with heat pipe, planar solar collector and heat recovery is designed to solve the energy problem of drying. Changes in drying air temperature, product mass loss and quality, contribution of heat recovery to the system in Karabuk province climatic conditions, constant 1 m/s drying rate, different irradiation values, were experimentally examined and theoretical analysis were made. In the experiment, which was carried out in the closed cycle without putting the product inside the systematic as determined that the dryer temperature increased to an average of 14.63 degrees C with an increase of approximately 49% at a constant air speed and an average irradiance value of 770 W/m(2). Kiwi fruit was used in the drying experiment with the product. In the kiwis dried in the oven, the moisture content calculated according to the wet base was 0.83 g water/g wet matter. the moisture, content calculated according to the dry basis was 4.94 g water/g dry matter and the dry matter amount was16.8%. The drying process was maintained until the last three weight values became equal and drying was carried out until the final moisture value was 0.03 g water/g dry matter. As a result of the measurements, an average drying was determined as 39.4 g and the weight of the product decreased by 80%. The general efficiency of the system at 15:50 on September 4, at an irradiation value of 694.3 W/m(2), is maximum 39%, the average efficiency of the heat pipe collector is 24%, and the efficiency of the heat recovery unit is 28%, 27% of the energy consumed in the drying process was met by the heat recovery unit and 73% by the heat pipe collector.Öğe The Design of Computer Controlled Cold and Hot Therapy Device with Thermoelectric Module(Amer Scientific Publishers, 2013) Yavuz, Celil; Yilmaz, Sezayi; Kaya, MetinIn this paper, a computer controlled cold-hot therapy device with thermoelectric module has been designed. This device is used in order to balance temperature of body in case of injury, fever etc. In this medical device, cold and hot therapy operations have been accomplished by changing the feeding voltage and feeding polarity of thermoelectric modules. Temperature was measured via PIC18F4550 microcontrollers and USB port and AD595AQ Monolithic Thermocouple Amplifiers were used for transferring data of K type temperature sensors to microprocessor. A control interface has been developed in VisualBASIC6.0 to monitor and record the temperature data, and control the device by the computer. All tests were conducted at variable temperature inside a heated chamber to simulate the human body temperature. The computer controlled cold-hot therapy device with thermoelectric module was operated and tested at variable water flow rates and variable voltages by computerized control. As a result of this study, cold and hot therapy operations have been realized via this medical device. Cold therapy with splint is a vital first aid application in Traffic, sports, work accidents etc. According to the literature, cold and hot therapy temperatures range from 0 degrees C to 15 degrees C and from 40 degrees C to 45 degrees C respectively. The study was performed at the simulated body temperature of 37 degrees C. The hot and cold therapy device which was designed was tested at various power values obtained cold surface temperatures from -3.4 degrees C to 5.5 degrees C and hot surface temperatures from 37.8 degrees C to 58.3 degrees C.Öğe Determination of drying characteristics of apples in a heat pump and solar dryer(Elsevier, 2009) Aktas, Mustafa; Ceylan, Ilhan; Yilmaz, SezayiBoth a heat pump and solar dryer were designed and manufactured. They were experimentally analyzed by drying apples, and a comparison was made between the two. Apples were sliced 4 mm thick, and dried from 4.8 (g water/g dry matter) moisture content to 0.18 (g water/g dry matter) at 3.3 kg/m(2)s-2.4 kg/m(2)s mass air velocity for 15 h in a heat pump dryer. Apples were also dried at the range of 3.3 kg/m(2)s and 2.9 kg/m(2)s mass air velocity from 4.8 (g water/dry matter) moisture content to 1 (g water/g dry matter) moisture content in the same period in a solar dryer. Effective moisture diffusivity was found to be 2.36 x 10(-8) m(2)/s in the heat pump dryer, and 1.03 x 10(-8) m(2)/s in the solar dryer. For both systems, the moisture ratio was analyzed with the Statgraphic program by using semi-theoretical models and compared to the empirical values. Correlation coefficients of the equations were calculated and standard error of estimation (SEE) and R-2 values were obtained.Öğe Determination of the heat transfer coefficient of PV panels(Pergamon-Elsevier Science Ltd, 2019) Ceylan, Ilhan; Yilmaz, Sezayi; Inanc, Ozgur; Ergun, Alper; Gurel, Ali Etem; Acar, Bahadir; Aksu, Ali IlkerIn this study, the efficiency of the rear-panel air velocity in cooling was investigated based on the temperature and solar radiation in the environment where the panels are located. During the cooling of the panels, the rear-panel temperature decreases, and accordingly, the open-circuit voltage of the panels increases. At present, the most important losses in panels are due to the increase in panel temperature depending on the solar radiation and outdoor air temperature. In this study, the rear-panel temperature changes were observed at 0-5 m/s air velocities and 10-40 degrees C. The calculations reveal that in winter weather conditions, the temperature of the panels did not increase at a level that would require cooling. This study investigated the heat transfer from the surface depending on the outdoor air temperature of the rear-panel air velocity and the changing rear-panel temperature. The effect of different outdoor air temperatures on the rear-panel heat transfer is minimal. When the air velocity was 5 m/s and the outdoor air temperature was 10-40 degrees C, the heat transfer in the Poly Crystal Solar panel was calculated as 11.6 W/m(2)K. (C) 2019 Elsevier Ltd. All rights reserved.Öğe Energetic and Exergetic Analyses of Experimentally Investigated Hybrid Solar Air Heater(Asce-Amer Soc Civil Engineers, 2023) Akdamar, Ismail; Dumrul, Hakan; Selimli, Selcuk; Yilmaz, SezayiSolar energy is a type of renewable energy that is readily available, but it must be converted to a usable form using a highly efficient method. The global energy problem that has surfaced in recent years shows the importance of both practical and scientific studies on using solar energy for space heating. Solar air heaters are large volume systems used for space heating. Research on the geometry and surface forms of solar air collectors is focused on reducing system volume and optimizing the use of solar energy. A photovoltaic (PV) module can be cooled with a fluid to prevent a decrease in efficiency due to heat while generating electrical power. The subject of this study is the idea of using the heat from cooling the modules to support a solar air heater. The improvement of the thermal performance of a solar air collector with a cooling thermal load of the concentrated photovoltaic thermal collector (CPV/T) was experimentally investigated. The heat exchanger, which removes the heat of the water-ethylene glycol circulating in the photovoltaic thermal collector, is mounted in the solar air heater's chamber of one of the two identical solar air heaters, and the first hybrid unit was obtained (i.e., first unit). The ordinary one was called the second unit. Heated air left the first and second units at average temperatures of 45.87 degrees C and 38.83 degrees C, respectively. Although the airflow rates in the units are the same, the air temperature in the first unit was increased by 18.13%. The heat contribution of the heat exchanger to the first unit was 128.96 W. The first and second law efficiencies of the first and second units were calculated as 51.89%, 15.22%, and 45.4%, 10.34%, respectively. The energetic and exergetic improvement of the first unit was found to be 6.49% and 4.88%, respectively. The local solar utilization capability is 797.76 kW middoth/year and 609.12 kW middoth/year for the first and second units, respectively. The waste heat from the CPV/T collector cooling cycle, which is 188.64 kW middoth/year, was recovered for heating air in the first unit. The recovery of waste heat for use in the first unit provided a significant performance improvement over the second unit. The environmental contribution of the waste heat recovery means 144 kg CO2 emission per year less in emission release. (C) 2022 American Society of Civil Engineers.Öğe Energy Analysis of Concentrated Photovoltaic/Thermal Panels with Nanofluids(Int Center Applied Thermodynamics, 2021) Dumrul, Hakan; Yilmaz, Sezayi; Kaya, Metin; Ceylan, IlhanIn this study, a prototype system was established for location heating application and electricity generation through utilizing two concentrated photovoltaic thermal panels (CPV/T) possessing flat surface receivers connected in series with each other. The purpose of the system is to supply the heating needs of a room in winter season and to meet the electricity requirement of the equipment used in this system. In the analysis of the installed system, different refrigerants (10% mono propylene glycol + 90% water and 0.5% Al2O3-water nanofluid) were tested at three different flow rates (0.4 m(3)/h, 0.5 m(3)/h, 0.6 m(3)/h). Throughout the experiments, the fan-coil air outlet temperature used to heat the room was adjusted to 35 degrees C with an inverter and a process control device. The results attained from the experiments carried out using different fluids throughout different months and days (April-May) have demonstrated that the thermal and electrical efficiencies of the system are found to be in good agreement with each other when evaluated in terms of the fluids utilized. The highest electrical energy recovery was found as 268 W at 0.6 m(3)/h flow rate for propylene glycol-water mixture and 194 W at 0.5 m(3)/ h flow rate for nanomixture. The total thermal energy efficiency for the system using different fluids was found to be around 22%. The total thermal energy gain of the system was also calculated as 2312 W at 0.6 m(3)/h for the propylene glycol mixture and 2041 W at 0.5 m(3)/h for the nanomixture.Öğe Energy and exergy analysis of surface water source heat pump system(Gazi Univ, 2023) Kocakulak, Serkan; Yilmaz, Sezayi; Ergun, AlperIn this study, energy and exergy analyzes were carried out to heat an experimental room with 28 square meter area by a surface water source heat pump (SWSHP) in the heating season, where placed in next to a river source (Arac stream) in Karabuk University. The system had a frequency inverter to change the compressor speed and the experiment was started at 35 Hz. in winter condition and completed when the indoor temperature reached 25.degrees C. While the COP value of the system was calculated as 2.58 on average, the highest exergy destruction was determined as 0.6 kW in the compressor in terms of the exergy analysis. The average exergy destructions were determined as 0.125 kW for the condenser, 0.152 kW for the expansion valve, 0.14 kW for the evaporator and fan coil system, and 0.06 kW for the water source heat exchanger. Exergy efficiencies were 60% for the compressor, 75% for the condenser, 85% for the expansion valve, 25% for the evaporator, 63% for the fan coil system and 8% for the water source heat exchanger. As a result of the study, it has been determined that the surface water source heat pump system works successfully in Karabuk province conditions.Öğe EXPERIMENTAL ANALYSES OF HEAT PUMP AND PARABOLIC TROUGH SOLAR FLUIDIZED BED DRYER(Turkish Soc Thermal Sciences Technology, 2015) Gurel, Ali Etem; Ceylan, Ilhan; Yilmaz, SezayiIn this study, both a heat pump and parabolic trough solar fluidized bed dryer were designed and manufactured. They were experimentally analyzed by first and second laws of thermodynamics and a comparison was made between the two. Drying air temperatures were controlled as PID for 40 degrees C set temperatures. Drying air temperature was controlled with a sensitivity of +/- 0.254 degrees C in heat pump dryer system and +/- 0.369 degrees C in parabolic trough solar dryer. In the heat pump dryer system, whole system heating coefficient of performance (COPts) was calculated as average 1.91. In parabolic trough solar dryer, heating performance coefficient (IPK) was calculated as average 3. Exergy loss was found to be 203.97 J/kg in the heat pump dryer, and 32.08 J/kg in parabolic trough solar dryer. Average exergy efficiency was found to be 31.1% in the heat pump dryer, and 63.37% in parabolic trough solar dryer.Öğe Experimental and numerical analysis of energy and exergy performance of photovoltaic thermal water collectors(Pergamon-Elsevier Science Ltd, 2021) Selimli, Selcuk; Dumrul, Hakan; Yilmaz, Sezayi; Akman, OzgurThe aim of this paper is the investigation and comparison of PV (Photovoltaic) module and PV/T (Photovoltaic/ Thermal) collectors regarding the energetic and exergetic point of view. A reference PV module and two different flow pattern PV/T collector was experimentally observed and evaluated results were compared concerning first and second law of thermodynamics. Experimentation results are also compared with the numerical results that were obtained by ANSYS Fluent software. Experimentation proceeded in Karabuk, Turkey. As a result, it was concluded that the PV module electrical efficiency is equal to its overall efficiency and is approximately 7.96%. Thermal, electrical, and overall energy efficiency values are 29.08%, 9.74%, and 38.82% for PV/T1, and PV/T2 are 49.68%, 10.19%, and 59.88%. The exergy efficiency of PV, PV/T1, and PV/T2 are determined at approximately 4.63%, 10.64%, and 11.53%. When the exergy efficiency values are compared, solar energy utilization in the renewable energy class for both PV/T collectors formed with the cooling units integrated with the PV panel has been almost doubled.Öğe Modeling of a mechanical cooling system with variable cooling capacity by using artificial neural network(Pergamon-Elsevier Science Ltd, 2007) Yilmaz, Sezayi; Atik, KemalCapacity modification in mechanical cooling systems can be performed by various methods. Changing condenser temperature also changes the capacity of the cooling system. In this study, a series of experiments were performed in order to determine the effects of changing cooling water flow rate (changing condenser temperature) in a mechanical heat pump experimental setup on the cooling capacity of the system. Power consumption, thermal efficiency, coefficient of performance (COP) of the system in various cooling capacities were estimated theoretically by using the data acquired from the experiments performed. Performance values obtained were used for training Artificial neural network (ANN) whose structure was designed for this operation. The Network, which has three layers as input, output, and hidden layer, has one input and four output cells. Six cells were used in hidden layers. Training was continued until the square error became (E < 0.005) in this ANN, for which back propagation algorithm was used for training. Desired error value was achieved in ANN and, ANN was tested with both data used for training ANN and data not used. Resultant low relative error value of the test indicates the usability of ANNs in this area. (c) 2007 Elsevier Ltd. All rights reserved.Öğe Theoretical and computational investigations of the optimal tip-speed ratio of horizontal-axis wind turbines(Elsevier - Division Reed Elsevier India Pvt Ltd, 2018) Bakirci, Mehmet; Yilmaz, SezayiAn important factor in the optimization of the geometry of a horizontal-axis wind turbine (HAWT) is the design tip-speed ratio (DTSR). Previous research has suggested that DTSR values between 6 and 8 are desirable. However, a different approach was used in this study. Two standard airfoils with aerodynamic properties that are specified in the wind turbine airfoil catalog were selected and six different HAWT geometries were generated using the Schmitz formula for three DTSR values. These geometries were investigated theoretically based on the blade-element momentum (BEM) theory and numerically by using computational fluid dynamics (CFD) to calculate the rotor power efficiency and the optimal tipspeed ratio (OTSR). The six HAWTs had an average maximum power coefficient of 0.54 and an OTSR of 8.2 when the airfoil properties given in the airfoil catalog were used; these values were 0.43 and 6.7, respectively, when the airfoil properties were calculated using CFD and 0.41 and 7.3 when the HAWTs were simulated using three-dimensional CFD. To determine the power coefficient and OTSR values based on the BEM theory, the maximum value of CL/CD should be carefully selected considering factors such as the Reynolds numbers. Based on these findings, it was concluded that the CFD results validated the BEM theorem; the differences between the results obtained by these methods were likely due to the assumptions used when applying the BEM theory. (C) 2018 Karabuk University. Publishing services by Elsevier B.V.Öğe Thermodynamic analysis of PID controlled fluidised bed dryer with parabolic trough collector(Inderscience Enterprises Ltd, 2015) Gurel, Ali Etem; Ceylan, Ilhan; Yilmaz, SezayiThe aim of the current study was to investigate how to use hot water obtained by parabolic trough collector (PTC) in an air handling unit. The system consisted of a PTC, a water depot, a pump, an air handling unit, a fan, and control equipments. The purpose of the system was to maintain the set value without using an additional heater in the air handling unit. During the process, +/- 0.36 degrees C accuracy was achieved in a 40 degrees C set temperature. Uncertainty analyses were made for the measured temperature value and they were obtained as +/- 0.44 degrees C. The energy and exergy efficiency were calculated for the system. The heating performance coefficient (HPC) was defined as the ratio of the obtained energy from the system to the compulsory energy supplied to the system. The HPC was calculated as 3 on average. Heat energy of the water in the depot was converted to heat energy of the air in the system with an average 52 % exergy efficiency.
