Akademik Veri Yönetim Sistemi
Tezin Türü: Doktora
Tezin Yürütüldüğü Kurum: Marmara Üniversitesi, Fen Bilimleri Enstitüsü, Makine Mühendisliği (İngilizce) Anabilim Dalı, Türkiye
Tezin Onay Tarihi: 2014
Tezin Dili: İngilizce
Öğrenci: EMİR AYDAR
Asıl Danışman (Eş Danışmanlı Tezler İçin): Mustafa Yılmaz
Özet:
An experimental study was conducted in accordance with EN442 in the standard test room in order to determine boundary conditions for computational study and verify numerical results. Tests were carried out in three different operating conditions. Turbulent natural convection coupled with thermal radiation in the test room and water flow inside the tested radiator were simulated together in order to compare with the experimental data obtained for this cavity at a Grashof number equal to 1.09x109. In carrying out numerical investigations, a three-dimensional, low-turbulence, two-parameter k–ε model known as the low-Reynolds-number k–ε turbulence model was used. Non-uniform temperature distribution on the front surface of tested radiators was observed. The difference between experimental and computational heat transfer rate are 1.70%, 2.27%, 10.03% in case of the excess temperatures of 50 °C, 60 °C, 30 °C, respectively. Quite good results are obtained for the excess temperature of 50 °C and 60 °C. For the lowest excess temperature, results are also in acceptable range. The study shows that computational methods can be applicable in the design of new heater types. In order to distribute the water in the vertical channels uniformly, modifications at panel section were performed. In order to decrease size and thus decrease cost, the proper length of the fin was determined. In order to get more efficient fin, fins with triangular profiles were investigated. It is found that the rate of heat transfer is increased by approximately 8% and weight is decreased by 17.22% using novel panel radiator compared to the rates obtained by tested panel radiator. Decreasing 9.95 percent in convection heat transfer performance in return for 1.79 percent reduction in the size and possibly the cost of the fin by using fins with triangular profiles. Fin efficiencies of the fins with triangular profiles are more efficient than the ones with parabolic profiles. It is also found that reducing the fin length from L=37mm (fin length of the tested radiator) to L=36mm in that case causes a raise of just 0.1 percent in heat transfer. Increasing 0.1 percent in heat transfer performance in return for 2.1 percent reduction in the size and possibly the cost of the fin.