Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Effect of Heat Absorbing Media on Thermal Performance of Air-Type Solar Collectors(Izmir Institute of Technology, 2005) Aydın, Kamil; İlken, Zafer; İlken, Zafer; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyIn this study, effect of heat absorbing media on the thermal performance of airtype solar collector is studied experimentally. Experimental setup was built and tested by using the ASHRAE 93-1986 standard named .Methods of testing to determine the thermal performance of solar collectors.. Polyurethane foam is used as heat absorbing media with a porosity of 85%. In the analysis three air speeds 3 m/s, 3,5 m/s and 4 m/s are used. Data for similar days are compared with each other. Increment of the efficiency related to the polyurethane foam is presented and performance curves of our air-type solar collector are indicated. Factors, affect the performance of collector, are discussed. Using heat absorbing media enhances heat transfer surface area and this increases efficiency, but pressure drop should be taken into consideration to prevent extra pumping power. In conclusion, efficiency values about 55% for 3m/s for ambient temperatures between 35 and 38oC, 60% for 4 m/s and 48% for 3,5 m/s for ambient temperature between 28 and 32oC with polyurethane foam are obtained. On the other hand, pressure drops increase from 0,015 kPa to 0,215 kPa for 3 m/s, from 0,01 kPa to 0,32 kPa for 3,5 m/s and from 0,01 kPa to 0,385 kPa for 4 m/s.Master Thesis A Theoretical Study on Enhancement of Heat Transfer in a Solar Air Heater Collector by Using Porous Media(Izmir Institute of Technology, 2011) Çekmer, Özgür; Mobedi, Moghtada; Mobedi, Moghtada; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyIn this study; a theoretical work is performed on heat and fluid flow in a solar-air heater collector partially filled with porous medium. The most of the efforts are paid to understand the characteristics of heat and fluid flow in a duct filled with the porous media. Various porous-clear media configurations are investigated. The buoyancy effects are neglected. The air flow in the channel is assumed to be incompressible, laminar, and hydrodynamically fully developed. For the porous regions, Darcy and Darcy-Brinkman models are used to obtain the velocity profile. In all chapters, dimensionless forms of the governing equations for the heat and the fluid flow are used. In the chapters with asymmetric cases, three different Nusselt numbers are defined; two individual Nusselt numbers for the upper and the lower wall, and an overall Nusselt number. The study is mainly focused on heat transfer enhancement by using porous media and only for a few cases pressure-drop analyses are performed. It is concluded that the use of a porous medium affects the heat transfer significantly, and the rate of effect is influenced by the thickness and location of porous media. Finally, a twodimensional study including thermally entrance region for an air-solar collector with partially filled porous medium is performed. It is observed that the outlet and mean temperature along the channel are significantly affected by upper wall energy loss, and thickness and conductivity of the porous medium.