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Öğe Şanlıurfa ilinde yatay yüzeye gelen anlık global güneş ışınımının modellenmesi(Dicle Üniversitesi, 2019-03-15) Karakaya, Hakan; Kallioğlu, Mehmet Ali; Avcı, Ali Serkan; Ercan, UmutBu çalışma ile Şanlıurfa ilinin iklim özellikleri ve topografik yapısı göz önüne alınarak yatay düzleme gelen aylık ortalama günlük global güneş radyasyonunun tespit edilebilmesi için literatürde yer alan 5 farklı model incelenmiştir. Sonuçlar istatistiksel karşılaştırma metotları, belirlilik katsayısı (R²), ortalama yüzde hata (MPE), sapma hatası (MBE), ortalama mutlak hata yüzdesi (MAPE), bağıl hata karesi (SSRE), bağıl standart hata (RSE), ortalama karekök hatası (RMSE), bağıl hata yüzdesi (e) ve t-istatistik (t-sat) ile olmak üzere dokuz farklı istatistik yöntemi ile karşılaştırılmıştır. Şanlıurfa ili için en uygun yaklaşım için bir sonuç verilmiştir. İstatistiksel hata sonuçlarına göre Cheegar ve Chibani Modeli yatay düzleme gelen global güneş ışınımı için Şanlıurfa ilinde kullanılacak en uygun model olarak belirlenmiştir. Sonuç olarak Şanlıurfa ili toplam güneş radyasyonu tahmini için polinom modelin tercih edilmesi önerilmiştir. Bu model verilerine göre Şanlıurfa ili için yıllık güneş enerjisi potansiyeli 4332,020 W/m2 /ay olarak belirlenmiştirÖğe Numerical and experimental investigation of solar chimney power plant system performance(Taylor & Francis, 2020-03-15) Karakaya, Hakan; Durmuş, Aydın; Avcı, Ali SerkanA prototype of a solar chimney power plant was performed by modeling in this study. The performed prototype was experimentally confirmed. Temperature, velocity, and radiation values were measured to actualize the confirmation. Experimental data that were obtained to determine the performance of solar chimney whose prototype was actualized by the help of measured values were computationally analyzed. The geometry of a solar chimney in the analysis was bidimensionally (2D) drawn on an axis of symmetry. The numerical simulation was analyzed with computational fluid dynamics (CFD) method. Since analysis results show that there is turbulent flow in system (RNG), k-ɛ turbulence model was used. Continuity, momentum, and energy equations were applied to the solar chimney system via the finite volume method. Moreover, DO (discrete ordinates) model was inserted in analysis to evaluate the radiation effect in the collector area. In addition to all these, correlation results between SPSS 17 statistics program and data obtained were evaluated. Finally, with reference to the comparison between numerical and experimental results, data obtained and numerical data are close to each other; the prototype is applicable to the real systems.Öğe Effects of ethanol addition to biodiesel fuels derived from cottonseed oil and its cooking waste as fuel in a generator diesel engine(Taylor & Francis, 2020-03) Karakaya, HakanExploration of energy sources such as renewable and non-edible vegetable oils has been continued during the recent two decades of 2000s. Cottonseed oil is a non-edible, abundant oil and is generally used as cooking oil. In the present study, the usability of biodiesel derived from both cottonseed oil and its cooking wastes was investigated by blending them with ULSD or ethanol in 50 percentages. B50, WB50, B50E50 and WB50E50, biodiesel and ethanol-contained fuels and ULSD were prepared for experiments. Combustion, performance, and emissions tests were conducted on a diesel engine used for power-producing electrical generator. In the combustion tests, cylinder pressure, HRR, CHR, MGT, and MFB were analyzed while MFC, BSFC, exhaust manifold temperature, and thermal efficiency were obtained in the performance tests. In the emissions tests, CO, HC, and NOx emissions were measured and compared with the results of ULSD. Combustion and performance findings of ULSD contained biodiesel blends were found more similar to those of ULSD. The duration of combustion stage can clearly be seen to be narrowed for ethanol-contained blend because of the rabid combustion characteristics of ethanol. Besides, the peak of HRR was found 10% higher for B50E50 while it was found averagely 8% for WB50E50 blends. NOx emissions were found 48% lower averagely for ethanol contained biodiesel blends that it is the most important finding of ethanol using with biodiesel. Besides, HC emissions were also found about 75% for biodiesel contained diesel fuel blends.Öğe Numerical and experimental study of air flow by natural convection in a rectangular open cavity cooled top and bottom surfaces(Batman Üniversitesi, 2016-12-28) Karakaya, Hakan; Durmuş, AydınBu çalışma ile ilk olarak kapalı kübik hacmin ön yüzeyinin çevreye açılmasıyla kübik boşluk haline gelen hacimde, alt ve üst yüzeyinden soğutma sınır şartında, laminer durumda doğal taşınım deneysel ve teorik olarak araştırılmıştır. Elde edilen ölçümler Fluent 6.3 paket programı yardımı ile çözülmüş ve deneysel veriler ile karşılaştırılmıştır. Doğal taşınım şartlarını sağlayabilmek için bu deneysel çalışma ile 2x2x1,8m ebatlarında bir şartlandırma odası uygulamaya dahil edilmiştir. Ayrıca deney düzeneğinin giriş ağzı bu şartlandırma odasına verilmiştir. Son olarak bu çalışma ile sıcaklık değişimi, hız vektörleri ve akım fonksiyonu grafikleri elde edilmiştir. Buna ek olarak Nusselt sayısının zamana bağlı değişimi teorik ve deneysel çalışmalar sonucunda elde edilmiştir.Öğe Phase changing material usage to increase the efficiency of photovoltaic panels(Balkan Yayın, 2020-01-31) Karakaya, Hakan; Şen, İzzetin EnesThe energy demand from renewable energy sources has been proportionally increased due to population growth. In renewable energy production, not only energy production but also efficient use is crucial. In recent years, photovoltaic panels, which are increasingly used and highly important in terms of renewable energy production, have warmed on the surface due to the radiation energy emitted by the sun, and this warmth reduces the efficiency of the panel. In this study, it is aimed to reduce this efficiency loss by using phase changing material with latent heat which is one of the thermal energy storage methods. One of the two solar panels placed parallel to the ground was filled with phase changing material. With this, it is aimed to cool photovoltaic panel by using calcium chloride hexahydrate phase changing material; and then radiation, air temperature, current, voltage, power, surface temperature, efficiency graphs were obtained. As a result of simultaneous measurements, the increase in yield was found to be 2.95%.Öğe Fotovoltaik panellerde verim iyileştirme yöntemleri(Academic Perspective Procedia, 2019-12) Karakaya, Hakan; Şen, İzzetin EnesÖğe Bir yüzeyinden ısıtılan kübik boşlukta doğal taşınımın incelenmesi(e-Journal of New World Sciences Academy, 2010-01) Karakaya, Hakan; Durmuş, AydınBu çalışmada başlangıçta kapalı kübik hacim olan ön yüzeyinin ortama açılmasıyla kübik boşluk haline gelen hacimde, arka yüzeyinden ısıtma sınır şartında doğal taşınım laminer durumda deneysel ve teorik olarak incelenmiştir. Sayısal sonuçlar Fluent 6.3 paket program kullanılarak çözülmüş ve deneysel sonuçlarla kıyaslanmıştır. Deneysel çalışmada doğal taşınım şartlarını sağlayabilmek için 2x2x1,8 m boyutlarında şartlandırma odası kullanılmış deney düzeneğinin giriş ağzı bu şartlandırma odasına açılmıştır. Çalışmada akım fonksiyonu, sıcaklık değişimi ve hız vektörleri grafikleri elde edilmiştir. Ayrıca teorik ve deneysel çalışmalar sonucunda Nusselt sayısının zamana bağlı değişimi elde edilmiştir.Öğe Bir yüzeyinden soğutulan kübik boşlukta doğal taşınım(e-Journal of New World Sciences Academy, 2010-01) Karakaya, Hakan; Durmuş, AydınBu çalışmada başlangıçta kapalı kübik hacim olan ön yüzeyinin ortama açılmasıyla kübik boşluk haline gelen hacimde, arka yüzeyinden soğutma sınır şartında, laminer durumda doğal taşınım deneysel ve teorik olarak incelenmiştir. Sayısal sonuçlar Fluent 6.3 paket program kullanılarak çözülmüş ve deneysel sonuçlarla kıyaslanmıştır. Deneysel çalışmada doğal taşınım şartlarını sağlayabilmek için 2x2x1,8m boyutlarında şartlandırma odası kullanılmış deney düzeneğinin giriş ağzı bu şartlandırma odasına açılmıştır. Çalışmada akım fonksiyonu, sıcaklık değişimi ve hız vektörleri grafikleri elde edilmiştir. Ayrıca teorik ve deneysel çalışmalar sonucunda Nusselt sayısının zamana bağlı değişimi bulunmuştur.Öğe Heat transfer and exergy loss in conical spring turbulators(Elsevier, 2013-05) Karakaya, Hakan; Durmuş, AydınIt would be misleading to consider only the construction costs of heat exchangers in their design because high service costs during their service life may also greatly increase total costs. Therefore energy saving aspects are very important in the design, construction and operation of the heat exchangers. For this reason, various active or passive methods have been sought to save energy by increasing the heat transfer coefficients in the cold and warm fluid sides in the heat exchangers. Conical spring turbulators (CST) are devised in this study. Performances of heat transfer and pressure drop in a pipe with the CST are experimentally examined for the CSTs’ angle (θ) of 30°, 45° and 60° in Reynolds number (Re) range of 10,000–34,000. Heat transfer, pressure loss and exergy analysis were made for the conditions with and without turbulators and compared to each other. Some empirical correlations expressing the results were also derived and discussed.Öğe Calculating energy-induced carbon footprint: Batman University case(European Journal of Technique (EJT), 2019-06-30) Karakaya, Hakan; Avcı, Ali SerkanThis study determined the energy-induced carbon footprint arising from energy consumption in Batman University. It is important for universities to do acts toward control the greenhouse gas emission based on energy consumption while performing activities. Therefore, there is need to know the components of carbon footprint. Electric energy, natural gas energy, and various oils as the energy consumption components in these institutions were scrutinized. Petrol, diesel fuel, and fuel oil were utilized as types of oil. It is seen that the component which considerably specifies the carbon footprint is 3.161.238 ton CO2 value and electric energy. Natural gas and fuel oil use contribute to carbon footprint at high ratios in winter months especially arising from heating. 361 ton CO2 based on natural gas use and 1.256.445 ton CO2 based on fuel oil use are other components which specify the carbon footprint. As a result, the primary carbon footprint for Batman University was determined by IPCC Methodology and Tier 1 approach; it is 3.162.855,445 ton CO2 for 2017
