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Öğe Assessment of a solar-assisted infrared timber drying system(Wiley, 2017) Aktaş, Mustafa; Ceylan, İlhan; Ergün, Alper; Gürel, Ali Etem; Atar, MusaThis study investigates convective-infrared drying characteristics of timber. The biggest disadvantage of infrared heating systems is the uncontrollable rise of the surface temperature up to extremely high values, which causes damage to the product. In this study, the power of an infrared system was controlled and adjusted according to the surface temperature of the product. In doing so, the surface temperature of the infrared heater was prevented from reaching up to values that could damage the product. During the analysis, the surface temperature of the timbers was kept at an average of 65 degrees C, while the bottom temperature was kept at an average of 45 degrees C. The air collector used in the system was found to be 50% efficient. At the end of a 13-h drying period, the moisture content of pine timbers could be reduced from 1.42 to 0.0948 g water/g dry matter. During the system analysis, parameters such as moisture content, mass diffusion coefficient, and useful energy rate were taken into consideration. (c) 2017 American Institute of Chemical Engineers Environ Prog, 36: 1875-1881, 2017Öğe Determination of the heat transfer coefficient of PV panels(Pergamon-Elsevier Science Ltd, 2019) Ceylan, İlhan; Yılmaz, Sezayi; İnanç, Özgür; Ergün, Alper; Gürel, Ali Etem; Acar, Bahadır; Aksu, Ali İlkerIn 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, exergetic, and thermoeconomic analyses of different nanoparticles-added lubricants in a heat pump water heater(Elsevier, 2022) Yıldız, Gökhan; Ağbulut, Ümit; Gürel, Ali Etem; Ergün, Alper; Afzal, Asif; Saleel, C. AhamedThe heat pumps are frequently used in domestic and industrial applications for hot water supply. The present paper aims to thermodynamically investigate the impacts of the nanoparticle-addition into the lubricants on the energetic, exergetic, and thermoeconomic aspects of a heat pump. In the experiments, air to the water heat pump is separately charged with various metal oxide-based nanoparticles (Al2O3, CuO, and TiO2)-added oils at a constant mass fraction of 0.5%. Polyolester (POE) and 134a are used as a lubricant, and refrigerant, respectively. The mass flow rates of the water passed through the condenser are varied from 10 to 25 g/s with an interval of 5 g/s. In the results, it is observed that the thermal conductivity value noteworthy increases with the presence of nanoparticles in POE. The highest increment in thermal conductivity is found to be 39% for POE + CuO in comparison with that of pure POE. Furthermore, with nanoparticles addition, it is noticed that the COP value generally improves, and the highest improvement for COP value is noticed to be 8% for POE + TiO2 nanolubricant at the mass flow of 25 g/s. Furthermore, exergy efficiency enhances by 3.6%, 1.8%, and 4.5% for POE + Al2O3, POE + CuO, and POE + TiO2, respectively. The lowest heating cost is calculated to be 3.465 c/kWh at 20 g/s flow rate for POE + Al2O3. In conclusion, this paper clearly reports that usage of nanoparticles along with lubricants is presenting better energetic, exergetic, and thermoeconomic results rather than the usage of lubricant alone in the heat pumps.Öğe Energy Analysis of a New Design of a Photovoltaic Cell-Assisted Solar Dryer(Taylor & Francis Inc, 2013) Ceylan, İlhan; Kaya, Metin; Gürel, Ali Etem; Ergün, AlperIn this study, a new type of solar dryer was designed and manufactured. This new solar dryer is composed of a heat pipe collector, a drying chamber, a load cell, an air circulation fan, photovoltaic cells (PvC), batteries, and halogen lamps. In this experimental study, tomatoes were used to test the drying process. The drying air was heated by the heat pipe collector and forced through the tomatoes by a blower fan during the daytime. The photovoltaic cells, which were used to run the fan, were also used to charge the batteries during the day. These charged batteries were used for running the halogen lamps during the night, when the halogen lamps were used to heat the drying-air-assisted photovoltaic cells. During the drying period, the drying air temperature, relative humidity, air flow rates, solar radiation, and loss of mass were measured in the solar dryer. Then, the measured data were used for energy analysis.Öğe Environmental and economic assessment of a low energy consumption household refrigerator(Elsevier B.V., 2019) Gürel, Ali Etem; Ağbulut, Ümit; Ergün, Alper; Ceylan, İlhanEnergy consumption is the biggest obstacle in the economic growth of a country. In recent years, Turkey has imported around at the rate of three-quarters of its total energy demand. Upon the past 10-years running, Turkey paid nearly half a trillion dollars for its total energy bill. The big share of energy consumption has emerged from buildings. Therefore, energy savings have great importance, particularly in the buildings. A refrigerator is responsible for the most dominant electrical energy consumption rate with 32% in a house. Therefore, this paper proposes a novel household refrigerator design for reducing energy consumption. In the proposed design, the necessary air for the cooling process will be provided from outdoor ambient in appropriate weather condition. The compressor work will, thus, be decreased via this way, and contribute to a reduction in energy consumption. The results indicated that this system in 63 provinces can be effectively used between 1 and 4 months and help to reduce 36 million $ in Turkish electric energy bill with the use of only 1 year period. Additionally, a reduction of approximately 850,000 tons of CO2 annually in Turkey can be achieved by applying the proposed design in this study. Hereby, Turkey can contribute not only to be sustained economic growth but also to reduce harmful gas emissions arising from electricity generation methods in the country. © 2019 Karabuk UniversityÖğe Estimation of global solar radiation on horizontal surface using meteorological data(Sila Science, 2012) Gürel, Ali Etem; Ergün, AlperIn the present study, the methods of Artificial Neural Networks (ANN) and Regression Analysis were used in estimating monthly average daily global solar radiation arriving on horizontal surface in Rize with the help of meteorological and geographic data like monthly average daily extraterrestrial radiation, monthly average daily hours of bright sunshine, day length, relative humidity, wind speed, temperature and declination angle. Mean bias error (MBE), root mean square error (RMSE) and t-statistic methods were used to evaluate performance of the estimation. It was seen at the end of the study that the equation obtained through multi-regression analysis method yielded better performance than that of obtained through ANN method.Öğe Klima Santrallerinde Yoğuşan Suyun Geri Kazanımı İçin Alternatif Yöntemler(2018) Gürel, Ali Etem; Ceylan, İlhan; Ergün, Alper; Acar, BahadırMerkezi ısıtma ve soğutma sistemlerinin en önemli parçası olan klima santrallerinde soğutucu serpantinüzerinden büyük miktarda su yoğuşmakta ve bu su genellikle en yakın gidere verilmektedir. Uygulamada da busu, büyük bir atık olarak nitelendirilmektedir. Hâlbuki özellikle %100 dış hava ile çalışan sistemlerdeki bu soğuksu depolanarak evaporatif soğutma da dâhil olmak üzere birçok uygulamada değerlendirilebilir. Bu çalışmada,klima santrallerinde yoğuşan suyun yeniden kullanımına yönelik farklı tasarımlar önerilmiştir. Çalışmada üçfarklı sistem üzerinde incelemeler gerçekleştirilmiştir. Birinci sistemde %100 taze havalı bir klima santralindenelde edilen yoğuşma suyunun, karışım havalı bir klima santralinin serpantininde ön soğutucu olarak kullanılmasıincelenmiştir. İkinci sistemde ise %100 taze havalı veya karışım havalı klima santralinin soğutucu serpantinindeyoğuşan suyun, bir soğutma kuleli chiller cihazında besleme suyu olarak değerlendirilmesi araştırılmıştır.Üçüncü sistemde ise %100 taze havalı veya karışım havalı klima santralinin soğutucu serpantininde yoğuşansuyun, hava soğutmalı kondenserli bir chiller cihazında kullanımı incelenmiştir. Yapılan psikrometrikhesaplamalar, %100 taze hava ile çalışan bir klima santralinde yaklaşık 80 kW’lık gizli ısının, tasarlanan busistemler aracılığıyla duyulur ısı olarak kullanılabileceğini göstermiştirÖğe The mathematical modeling of concentrated photovoltaic module temperature(Pergamon-Elsevier Science Ltd, 2017) Ceylan, İlhan; Gürel, Ali Etem; Ergün, AlperIn this study, we examined the effect of the use of paraffin wax on the panel temperature of concentrated solar panels. Some tests were performed on various days for three months (including spring, summer, and winter months). With the help of the experimental results, new approaches have been made as concentrator ratio, area ratio, concentrator efficiency and power coefficient. As a result of this approaches the concentrator ratio was found to be 3. When the concentrator ratio was 3, the panel temperature of the system with paraffin was found to be between 80 and 100 degrees C, while that of the other system was found to be above 100 degrees C. Panel efficiency might be reduced down to 10% at these temperatures. The study also included the development of a mathematical model of the changes in the panel temperature of the concentrated systems in which paraffin was not used. The temperature at the back of the panels could be calculated by this mathematical model, depending on the ambient temperature and the concentrated solar radiation. The correlation coefficient of the mathematical model was found to be 0.929. The test results of two days, which were not included in the model, were used to determine the reliability of the model, and the panel temperatures were calculated using the correlation coefficients of 0.933 and 0.966. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Öğe Performance analysis of a concentrated photovoltaic and thermal system(Pergamon-Elsevier Science Ltd, 2016) Ceylan, İlhan; Gürel, Ali Etem; Ergün, Alper; Tabak, AbdulsamedThe purpose of the present study is PV/T system, which designed and implemented in order to reuse of thermal energy while increasing of electric production. Solar radiation was increased with the concentrator about two folds and electrical power gains were increased. A paraffin wax was used to store latent heat as a thermal energy storage. Thermal energy was combined with a greenhouse like air drier and used to dry the product. Thermal and electrical energy gain in the concentrated and non-concentrated panels were compared and total system efficiency was analyzed. The maximum temperature obtained at the back of the panel was calculated as 37 degrees C and the panel efficiency was 11% at mean solar radiation was 2000 W/m(2). (C) 2016 Elsevier Ltd. All rights reserved.Öğe Performance analysis of using CuO-Methanol nanofluid in a hybrid system with concentrated air collector and vacuum tube heat pipe(Pergamon-Elsevier Science Ltd, 2019) Kaya, Metin; Gürel, Ali Etem; Ağbulut, Ümit; Ceylan, İlhan; Çelik, Selim; Ergün, Alper; Acar, BahadırAn experimental study was conducted to determine the effects of adding copper oxide (CuO) with 50 nm diameter into neat methanol (CH3OH) on the energetic and exergetic analysis of a concentrated air collector with vacuum tube heat pipe at different air velocities (1, 2 and 3 m/s). The experimental results clearly indicated that the nanofluid application enhanced the thermal properties and provided better performance for heat pipe applications. Considering all air velocities together, the average efficiency for neat methanol and CuO-Methanol nanofluid was achieved by 65% and 64%, respectively. Additionally, the average specific exergy outlet values for neat methanol and CuO-Methanol nanofluid were calculated as 206 J/kg and 298 J/kg, respectively. In the experiments, it is seen that the efficiency values of the system using the CuO-Methanol nanofluid reached higher values, as the solar radiation values were higher. In conclusions, this paper distinctly suggests that the presence of copper oxide in the base fluid can be used in a concentrated air collector with vacuum tube heat pipe particularly at the high radiation conditions and positively affects the performance of the system.Öğe Solarmeter Design for High Solar Radiation Measurement and Experimental Validation(2019) Ergün, Alper; İlhan, Görkem Ceylan; Aydın, Mustafa Aydın; Gürel, Ali Etem; Koçbulut, GökçeIn this study, a solar meter was designed to measure high solar radiation. The solar meter uses the characteristic properties of a solar cell in order to measure solar radiation. In this way, measurements can be carried out without any limitations. The solar radiation equation was entered into the ARDUINO microcontroller in the solar meter, and the results were compared through another commercial solar meter. These results were entered into STATGRAPHIC software and three different functions with high regression values were obtained. These three functions were entered into the Arduino microcontroller and the experiments were repeated. According to the comparisons made using commercial device, R2 values were determined as 0.944, 0.936, 0.938, and 0.986 for the first equation and for three different functions, respectively. Based on the values obtained, it has been determined that the solar meter can make highly accurate measurements and after the development of appropriate functions, it can be employed especially in high solar radiation concentrated systems.Öğe Ticari Soğutma Sistemlerinde R22 Akışkanının Alternatifi Olarak R438a ve R417a Akışkanlarının Performansının İncelenmesi(2018) Ergün, Alper; Gürel, Ali Etem; Ceylan, İlhanBu çalışmada, özellikle soğuk depoculukta ve iklimlendirme sistemlerinde oldukça yaygın olarakkullanılan R-22 soğutucu akışkanına alternatif olarak piyasaya sürülen ve ozon tabakasına dostolan, iki soğutucu akışkan R-417A ve R-438A termodinamik açıdan incelenmiştir. Yapılançalışmada, R-22, R-417A ve R-438A soğutucu akışkanlarının performansları karşılaştırılmıştır.Her 3 soğutucu akışkan da değişken yük koşulları altında (-8C, 0C, -25C ve -31C) bilgisayarortamında bir simülasyon ile gerçekleştirilmiştir. Farklı evaporasyon sıcaklıkları için, soğutucuakışkanların performansları termodinamiğin birinci ve ikinci kanunu kullanılarakdeğerlendirilmiş ve sistemlere ait performans katsayıları (COPh ve COPC) hesaplanmıştır.Çalışmanın sonunda, R22 soğutucu akışkanına alternatif olarak geliştirilen R417A ve R438Aakışkanlarından, R438A akışkanının daha yüksek COPh ve COPC değerlerine sahip olduğuhesaplanmıştır. Ayrıca kondenser ve kompresör yükleri incelendiğinde yine R438A akışkanının,R417A akışkanına göre daha olumlu değerlerde olduğu gözlenmiştir. Sonuç olarak incelen 3akışkan için R22 akışkanına en iyi alternatifin R438A olduğu tespit edilmiştir.
