Yazar "Sertkaya, Ahmet Ali" seçeneğine göre listele
Listeleniyor 1 - 9 / 9
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Alüminyum köpüğün ısı değiştiricisi olarak tasarımı ve ısı transferi modeli(Selçuk Üniversitesi Fen Bilimleri Enstitüsü, 2008-05-15) Sertkaya, Ahmet Ali; Altınışık, KemalBu çalışmada, geniş bir kullanım alanı bulunan açık hücreli Alüminyum köpüğün ısı değiştiricisi olarak kullanımı amaçlandı. Çalışma teorik ve deneysel olarak gerçekleştirildi. Alüminyum köpük ısı değiştiricisinin ısı transfer modeli için üç boyutlu matematik model kuruldu. Üç boyutlu olarak elde edilen diferansiyel denklemin çözümü için sınır şartları yazıldı. Denklem ayrıklaştırılarak bilgisayar çözümü için kompakt form haline getirildi. Turbo Pascal 7.0 programı kullanılarak Gauss – Seidel İterasyon Yöntemi ile diferansiyel denklem çözüldü. θ-X, θ-Y ve θ-Z’in porozite ve birim hacimdeki yüzey alanına göre değişimlerinin grafikleri elde edildi. Deneysel çalışmada 200x200x100mm boyutlarında üç geçişli, her geçişte 6 boru bulunan ve saptırmalı olarak dizilen üç ayrı ısı değiştiricisi dizayn edildi. PPI 10, 20 ve 30 özelliklerine sahip ısı değiştiricilerin ısıl etkenliklerini karşılaştırmak için, toplam 500’ün üzerinde deney yapıldı, hesaplamalarda sadece 252’si dikkate alındı. Deney sonuçları SPSS 11 İstatistik Paket Programı yardımıyla Reynold sayısının 5.103Öğe Çift fazlı güneş enerjisi kaynaklı ısı pompası sisteminin teorik ve deneysel incelenmesi(Selçuk Üniversitesi Teknik Bilimler Meslek Yüksekokulu, 2011) Samancı, Ahmet; Altınışık, Kemal; Sertkaya, Ahmet AliBu çalışmada, soğuk iklim bölgelerinde konutların ısıtılması için hava-hava çalışan bir ısı pompasına çift fazlı güneş enerjisi destekli düzlemsel güneş kollektörü kaynak olarak kullanıldı. Çalışma, teorik ve deneysel olarak gerçekleştirildi. Teorik çalışmada, sistemin matematik modelini oluşturmak için, sisteme giren ve çıkan tüm büyüklükler ayrı ayrı ifade edildi. Daha sonra deneysel çalışmada öngörülen aylar için Konya Meteoroloji Bölge Müdürlüğünden alınan son 15 yıla ait veriler kullanılarak teorik sonuçlar elde edildi. Deneysel çalışma, Aralık, Ocak ve Şubat ayları için yapıldı. Çift fazlı güneş kollektöründe R–11, ısı pompası sisteminde ise R–22 akışkan olarak kullanıldı. Kollektördeki buharlaşmayı hızlandırmak için boru içerisine özel formda hazırlanan profiller yerleştirildi. Hava+su-hava çalışan sistemin konvansiyonel sisteme göre Isıtma Tesir Katsayısı (ITK)’ nda %24 lük bir artış sağladığı tespit edildi. Ölçümlerden kaynaklanan hata nedeniyle deneysel sonuçlardan elde edilen ITK değerinin, teorik sonuçlara göre biraz düşük olduğu gözlendi.Öğe Designing of open cell aluminum foam heat exchanger and modelling of its thermal performance by using ann method(GAZI UNIV, 2016) Sertkaya, Ahmet Ali; Ateş, Ali; Altınışık, KemalThis study deals with the design and thermal performance modeling of aluminum foam open cell heat exchangers by making use of experimental data where the aluminum featuring different numbers of pores per inch (PPI) was used and the modeling was based on the Artificial Neural Networks (ANN) method. The open celled aluminum foams with 10, 20 and 30 PPI features were shaped into heat exchangers. The heat exchangers were placed into a rectangular groove then hot water was circulated within the heat exchanger tubings and cold air generated from a fan was blown over the tubings at varying rates. For every heat exchanger, the variations of Reynolds number with Nusselt number, pressure drop with air speed, and friction with Reynolds number were presented on graphs. By making use of the experimental data, ANN modeling was carried out for materials with 10, 15, 20, 25 and 30 PPI porous densities. The ANN input parameters for the developed system were T-hin, T-cin, T-hinw, u and PPI, whereas the output parameters were chosen to be T-hout, T-cout, T-houtw and Delta P. When the results from the Artificial Neural Networks were analyzed and compared with the experimental results, it was found that a close correlation exists between the two. With the result of this study, it becomes clear that the Artificial Neural Networks numerical modeling can be safely applied to aluminum foam heat exchangers.Öğe DETERMINATION OF THE THERMOPHYSICAL PROPERTIES OF A ZEOLITE NANOFLUID(BEGELL HOUSE INC, 2018) Sertkaya, Ahmet AliIn this study, the thermophysical properties of the nanofluid prepared by adding as basic fluid 1.3% zeolite nanoparticles into water were determined. Many researchers are working to improve the performance of heat transfer fluids. One of the methods used for increasing the overall thermal conductivity of the fluid is the addition of high thermal conductivity materials such as metal oxides, metals, and carbon as nanosized particles to heat transfer fluids. In this study, the specific heat capacity, thermal conductivity, and viscosity of the nanofluid obtained with zeolite nanoparticles in order to increase the fluid's thermal performance were investigated experimentally. Studies of nanofluids with zeolite nanoparticles are lacking in the literature.Öğe Experimental and Numerical Analysis of one Dimensional Heat Transfer on Open Cell Aluminum Foams(GAZI UNIV, 2015) Sertkaya, Ahmet Ali; Ateş, Ali; Altınışık, Kemal; Dinçer, KevserIn this study, one dimensional heat transfer of open cell aluminum metal foams is investigated both experimentally and by using numerical methods as well. Open cell aluminum foams with pore densities of 10, 20 and 30 (Number of Pores Per Inch) PPI were shaped into heat exchangers. The foams having sizes of 200 x 100 x 20 mm were insulated on their three faces. Steady heat flux was maintained on the base section of the foam by heating a plate shaped coil electrically. Temperature distributions on the vertical sections and mostly on locations near heaters were measured with the thermocouples located on the aluminum foams. With the help of the recorded temperatures from the tests the graphs of open cell aluminum foams with pore densities of 10, 20 and 30 were plotted. First of all, one dimensional heat transfer equations were derived for the numerical solution of the system. The governing equations obtained were then discretized by using the Central Difference Method and finally solved with the Finite Difference Method. The results obtained were converted into graphs and compared with the empirical results obtained beforehand. The fastest drop in temperature close to the heater was observed at the foam with 10 PPI while the lowest falling rate took place at the foam with 30 PPI pore density. At an interval of three aluminum foams, the temperature difference was found to be higher near the heater and lower away from the heater. It was found that both experimental and numerical results are closely related.Öğe Experimental investigation of the effects of orientation angle on heat transfer performance of pin-finned surfaces in natural convection(PERGAMON-ELSEVIER SCIENCE LTD, 2011) Sertkaya, Ahmet Ali; Bilir, Sefik; Kargici, SunaNatural convection heat transfer in air from a pin-finned surface is investigated experimentally by considering the effect of radiation heat transfer. The plate was oriented as the pin arrays facing either downwards or upwards from vertical axis with different angles and the experiments were performed for different values of heater power input. From the results of the experiments it is observed that the pin fins increase the heat transfer considerably when compared to the unpinned surface. The upfacing pins are more enhancing heat transfer than the downfacing pins and the enhancement is decreasing with increasing orientation angle from the vertical axis. (C) 2011 Elsevier Ltd. All rights reserved.Öğe Experimental investigation of thermal performance of aluminum finned heat exchangers and open-cell aluminum foam heat exchangers(ELSEVIER SCIENCE INC, 2012) Sertkaya, Ahmet Ali; Altınışık, Kemal; Dinçer, KevserIn this study six heat exchangers were experimentally investigated; three of them were aluminum foam heat exchangers and the other three were aluminum fin heat exchangers. The open cell aluminum foam heat exchangers were of PPI 10, 20, 30 features and dimensions of 200 x 200 x 100 mm. The aluminum fin heat exchangers were of the same dimensions as the open cell aluminum heat exchangers and with fin intervals of 1.6, 3.2, 4.8 mm. By using experimental data, variations of effectiveness versus velocity, pressure loss versus velocity, friction factor versus Reynolds number and Reynolds number versus Nusselt number have been investigated. The Reynolds number used in the tests was at around 5 x 10(3)-9 x 10(4). It was found that, for both types of heat exchangers, as the velocity of refrigerant increases, the effectiveness drops and pressure loss increases. The effectiveness was higher at lower Reynolds numbers. It was found that aluminum fin heat exchangers transfer much more heat than their aluminum foam counter parts. (C) 2011 Elsevier Inc. All rights reserved.Öğe Pimli yüzeylerde doğal taşınım ile ısı transferi(Selçuk Üniversitesi Fen Bilimleri Enstitüsü, 1999-09-23) Sertkaya, Ahmet Ali; Kargıcı, SunaBu çalışmada, pimli yüzeylerde doğal taşınım ile ısı transferi ışınım ile ısı transferinin etkileri de dikkate alınarak incelenmiştir. Plakalar pimler aşağıya ve yukarıya bakacak şekilde düşeye göre farklı açılar ile ayarlanmış ve deneyler her konum için farklı giriş güçlerinde tekrarlanmıştır. Elde edilen sonuçlardan pimlerin ısı transferini önemli ölçüde arttırdığı ve yukarı bakan pimlerin aşağı bakan pimlere kıyasla daha fazla ısı transferi yaptığı belirlenmiştir. Düşeye göre açının arttırılması ise ısı transferini azaltıcı yönde etki yapmıştır.Öğe Rule-based Mamdani-type fuzzy modelling of thermal performance of fintube evaporator under frost conditions(E D P SCIENCES, 2016) Özen, Dilek Nur; Altınışık, Kemal; Dinçer, Kevser; Ateş, Ali; Sertkaya, Ahmet Ali; Tolu, Muhammed EminFrost formation brings about insulating effects over the surface of a heat exchanger and thereby deteriorating total heat transfer of the heat exchanger. In this study, a fin-tube evaporator is modeled by making use of Rule-based Mamdani-Type Fuzzy (RBMTF) logic where total heat transfer, air inlet temperature of 2 degrees C to 7 degrees C and four different fluid speed groups (ual=1; 1.44; 1.88 m s-1, ua2=2.32; 2.76 m s-1, ua3=3.2; 3.64 m s-1, ua4=4.08; 4.52; 4.96 m s-1) for the evaporator were taken into consideration. In the developed RBMTF system, outlet parameter UA was determined using inlet parameters Ta and ua. The RBMTF was trained and tested by using MATLAB (R) fuzzy logic toolbox. R-2 (%) for the training data and test data were found to be 99.91%. With this study, it has been shown that RBMTF model can be reliably used in determination of a total heat transfer of a fm-tube evaporator.
