Yazar "Dumrul, Hakan" seçeneğine göre listele
Listeleniyor 1 - 10 / 10
Sayfa Başına Sonuç
Sıralama seçenekleri
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 Effectiveness of heat sink fin position on photovoltaic thermal collector cooling supported by paraffin and steel foam: An experimental study(Pergamon-Elsevier Science Ltd, 2022) Al Hariri, Ahmad; Selimli, Selcuk; Dumrul, HakanForced convective cooling effectiveness on photovoltaic thermal collector electrical and thermal performance was experimentally studied with phase change material (paraffin) + steel foam mixture and two different angular positioned finned heat sink attachments. Fins are positioned flat and inclined, and air was forced with fan to flow between them. Solar radiation, temperature, electrical and thermal power, energy, and exergy efficiencies were determined and compared with reference photovoltaic module data. The first photovoltaic thermal collector was constructed with phase change material (paraffin) + steel foam mixture application to the back surface and covering with an incline finned heat sink. The second one was assembled with phase change material (paraffin) + steel foam filling to back surface and covering with a flat finned heat sink. Incline and flat finned heat sink attached collectors were cooled 12.23% and 21.67% relatively more than photovoltaic module. Electrical efficiency improvement with incline finned and flat finned heat sink application acquired approximately 5.09% and 6.18% relative to the photovoltaic module, which has 4.38% electrical efficiency, thanks to the cooling provided. The overall efficiencies were 41.4% and 59.53%. Photovoltaic module exergy efficiency is 4.67%, it is increased to 5.59% and 6.87% by cooling with incline finned heat sink and flat finned heat sink applications. Utilizable energy enhancement is identified approximately 140.32 kWh/year and 207.42 kWh/year by assuming 2738 h annual sunshine time in Turkey. These potentials rely on increase in electrical efficiency and heat recovery during cooling of PV/T collectors with incline and flat finned heat sinks. The predicted energy profit can be estimated at $7.01/year and $10.37/year, and its equivalent in emission reduction can be 115.76 kg center dot CO2/year and 171.12 kg center dot CO2/year.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 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 Investigation of Obtaining Natural Humic Acid From Asphaltites Commonly Found in Sirnak-Uludere Region(Gazi Univ, 2022) Taskesen, Edip; Acar, Sukru; Arli, Fatih; Dumrul, Hakan; Ertugrul, Gorkem; Bulbul, Saban; Ozcan, EmineThe physical and chemical properties of asphaltites found in significant amounts in Sirnak and its surroundings are close to coal. But it differs from coal because of its formation sources and chemical processes. Asphaltites were separated from the oil in liquid state by tectonism and settled in other locations, hardened by chemical reactions during geological processes and turned into solid phase. Most of the heating need in the Southeastern Anatolia Region is met by asphaltites. However, it is a raw material with low calorific value, high content of ash, sulfur and moisture, and high potential to adversely affect air pollution.It contains nitrogen and humic acid that dissolves slowly in aqueous media and can be used as soil reinforcement. In this study, researches were made to obtain natural humic acid from the content of asphaltite samples taken from the mine reserve in Uludere district. In the experiments made with samples, the effects of pH changes, temperature changes, changes in mixing times, precipitation in KOH and HCl solution were investigated towards optimal humic acid recovery efficiency. Accordingly, natural humic acid was obtained with the highest efficiency of 33.95% as a result of the studies conducted with temperature experiments from the sample of the Uludere region.Öğe PARABOLİK OLUKLU FOTOVOLTAİK TERMAL KOLEKTÖRÜN (PV/T) İKLİMLENDİRME SİSTEMİNE UYGULANMASI(2022-06) Dumrul, HakanBu tez çalışmasında, Karabük Üniversitesi yerleşkesi içerisinde 54 m3 hacme sahip, deneyler için yapılmış bir mahalin iklimlendirilmesinde yaz ve kış şartları için sistem tasarlanmış ve kurulmuştur. Sistemlerde kullanılan yoğunlaştırıcılı fotovoltaik/termal kolektörlerden (CPV/T) elde edilen elektrik enerjisi sistem ekipmanlarının çalıştırılmasında, ısı enerjisi (termal enerji) de kış uygulamasında mahal ısıtılmasında kullanılmıştır. Yaz uygulamasında ise mahalin soğutulması için doğal kaynak (kuyu suyu) kullanılmıştır. Kullanılan kuyu suyunun temininde enerji olarak CPV/T’lerden yararlanılmıştır. Aynı zaman da mahalde soğutma işlemi gören su CPV/T’lerin soğutulması amacıyla kullanılmıştır. Kış uygulaması nisan ve mayıs aylarında 0.4, 0.5 ve 0.6 m3/sa debileri için %10 mono Propilen Glikol (PG)/%90 su ve hacimce %0.5’lik Al2O3/su nanoakışkanı kullanılarak gerçekleştirilmiştir. Odanın ısıtılmasında kullanılan fan-coil hava çıkış sıcaklığı invertör ve proses kontrol cihazı ile 35 ºC’ye ayarlanmıştır. Ortalama yoğunlaştırılmış güneş ışınımının 1056 W/m2 olduğu ve dış hava sıcaklığının en düşük 8 ºC en yüksek 26 ºC arasında değiştiği durumlarda ortalama fan-coil hava çıkış sıcaklığı 33 ºC ve oda sıcaklığı ortalama 24.6 ºC olarak ölçülmüştür. Elektriksel enerji kazanımı en yüksek PG/su karışımı için 0.6 m3/sa debide 268 W, nanoakışkan için 0.5 m3/sa debide 194 W olarak hesaplanmıştır. Farklı akışkanların kullanıldığı sistem için toplam termal enerji verimi yaklaşık %22 olarak belirlenmiştir. Sistemin toplam termal enerji kazanımı PG/su karışımı için 0.6 m3/sa debide 2312 W nanoakışkan için ise 0.5 m3/sa debide 2041 W olarak hesaplanmıştır. Sistemden elde edilen toplam ekserji çıkışı PG/su karışımı için ortalama 380.6 W, Al2O3/su nanoakışkanı için 315.4 W olmuştur. Sistemin bu ekserji çıkış değerlerinde her iki akışkan içinde ekserji verimi ortalama %7 olarak hesaplanmıştır. Yaz uygulamasında deneyler temmuz ayında farklı günlerde 0.15, 0.2, 0.25, 0.3, 0.4 m3/sa sabit fan-coil kuyu suyu debilerinde gerçekleştirilmiştir. Deneyler süresince odanın soğutulmasında kullanılan fan-coil hava çıkış sıcaklığı invertör ve proses kontrol cihazı ile 20 ºC’ye ayarlanmıştır. Ortalama ışınımın 766 W/m2, ortalama yoğunlaştırılmış ışınımın 1101 W/m2, ortalama kuyu suyu sıcaklığının 16 ºC olduğu ve dış ortam sıcaklığının en düşük 23 ºC en yüksek 33 ºC arasında değiştiği durumlarda ortalama fan-coil hava çıkış sıcaklığı 18 ºC, ortalama oda sıcaklığı 23 ºC ve ortalama CPV/T kolektör çıkış suyu sıcaklığı 24 ºC olarak ölçülmüştür. Sistemden elde edilen ortalama toplam termal enerji kazanımı 636.7 W olarak bulunmuş ve bu güç değerinde ortalama termal enerji verimi %12.4 olarak hesaplanmıştır. CPV/T kolektörlerden elde edilen en yüksek elektriksel güç 0.4 m3/sa debide 206.2 W olarak ölçülmüştür. Farklı gün ve debilerde gerçekleştirilen deneylerde sistemden elde edilen ortalama toplam ekserji çıkışı 353.2 W olarak bulunmuş ve ortalama ekserji verimi %7.3 olarak hesaplanmıştır.Öğe Space cooling with groundwater pumped by a solar driven pump(2023) Dumrul, Hakan; Selımlı, Selcuk; Yılmaz, Sezayi; Korkmaz, BarışIn this study, it was experimentally investigated that the groundwater of a well is brought to the surface using solar energy, which is one of the renewable energy sources, and the cooling of a place with this water with low energy density. The study evaluated cooling performance on two different days (Exp. 1 and Exp. 2) and at two different cooling water flow rates. The efficiency of the PV system was found to be 8.33±0.44% in Exp. 1 and 8.3±0.44% in Exp. 2. The cooling loads of the cooled buildings differ in Exp. 1 and Exp. 2 due to ambient conditions. The cooling load in Exp. 1 was determined to be 572±22.8 W and in Exp. 2 about 828±33.1 W. The heat loads extracted from the building by the groundwater used as a cooling fluid are 410±16.4 W and 786±31.4 W for Exp. 1 and Exp. 2. The cooling performance evaluation criteria (CPEP) value was found to be 0.72 for Exp. 1 and 0.95 for Exp. 2. Although there was a significant difference between the cooling loads for Exp. 1 and Exp. 2, the cooling load coverage increased with the increase in cooling water flow rate according to the CPEP values. Although in both experiments the cooling load was not fully met and the temperature inside the structure rose slightly during the experiment, it was kept cool.Öğe Şırnak-uludere bölgesinde yaygın olarak bulunan asfaltitlerden doğal hümik asit elde edilebilirliğinin incelenmesi(2022) TaskeŞen, Edip; Acar, Şükrü; Arlı, Fatih; Dumrul, Hakan; Ertuğrul, Görkem; Bülbül, Saban; Özcan, EmineŞırnak ve çevresinde önemli miktarlarda bulunan asfaltitlerin, fiziksel ve kimyasal özellikleri kömüre yakındır. Fakat oluşum kaynakları ve kimyasal süreçler nedeniyle kömürden farklıdır. Asfaltitler, tektonizmayla sıvı haldeki petrolün kendi konumundan ayrılarak başka konumlara yerleşip, jeolojik süreçler boyunca kimyasal reaksiyonlarla sertleşip, katı faza dönüşmüştür. Güneydoğu Anadolu Bölgesi’nde ısınma ihtiyacının çoğu asfaltitlerden karşılanmaktadır. Ancak, düşük ısıl değeri, yüksek oranlarda kül, kükürt ve nem içeriği sahip olmalarıyla kalorisi düşük ve hava kirliliğine olumsuz etki etme potansiyeli yüksek hammaddedir. Yapısında azot ve sulu ortamda yavaş çözünen hümik asit bulunmakta ve toprak güçlendirici olarak kullanılabilir. Bu çalışmada, Uludere ilçesinde bulunan maden rezervinden alınan asfaltit numunelerinin içeriğinden doğal hümik asitin elde edilmesine yönelik araştırmalar yapılmıştır. Numuneler ile yapılan deneylerde optimal humik asit kazanma verimine yönelik, pH değişimleri sıcaklık değişimleri, karıştırma sürelerinin değişimleri, KOH ve HCI çözeltisindeki çöktürmenin etkileri incelenmştir. Buna göre Uludere bölgesi numunesinden sıcaklık deneyleri ile yapılan çalışmalar sonucunda en yüksek % 33,95 verimle doğal hümik asit elde edilmiştir.
