Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis An Experimental Study on Enhancement of Heat Transfer in a Solar Air Heater Collector by Using Porous Medium(Izmir Institute of Technology, 2012) Maraba, Gizem; Özerdem, Barış; Özerdem, Mehmet Barış; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe aim of this thesis is to enhance the heat transfer of a solar air heater by using porous material. A comprehensive literature survey has been carried out to learn the previous researches. Depending on this literature survey, some design parameters were determined and a solar air heater was constructed to the Solar & Wind Energies Laboratory according to this parameters. In order to obtain the optimum design parameters and maximum efficiency of solar air heater, several studies have been carried out including clear and porous material assisted channels. For this purpose different configurations and designs were investigated and tested. Temperature data along the collector, average velocity of air inside the channel, pressure drop due to the porous material, power that fan and electrical heater consumes were measured and tabulated regularly. Related graphs were drawn according to the experimental results. The effect of porous material on the heat transfer and collector efficiency was discussed based on these graphs.Master Thesis Theoretical Modeling and Designing a Line-Focused Horizontal -Receiver Solar Thermal Power Plant(Izmir Institute of Technology, 2005) Yazıcı, Osman Can; Subaşılar, Bedrettin; Subaşılar, Bedrettin; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyIn this study astronomical formulas that are necessary for the mechanical structure of a line focused horizontal receiver-solar thermal power plant are examined. The subjected Power Plant is designed with "Linear Fresnel Reflectors".The astronomic formulas are developed to focus the sunrays on a receiver continuously with the single axis orientation of multiple planar reflectors. Rotation axis of the planar reflectors are placed North / South direction. By means of this study it is possible to determine the exact position of the sunrays on the receiver that is reflected from the planar reflectors. Both conditions for the horizontal and inclined placement of the power plant are studied separately. Rotation angles are used by evaluating the formulas.Considering changing sun position, it is shown that changes in the rotation angle for all of the planar reflectors are equal for continuous focusing. By means of this once the system is adjusted it can be controlled with a single motor for entire year. With the help of the equations evaluated during the study a small model is projected. For scaling the model the parabola is chosen from the Fresnel design principle. Then the reflector amount, reflector widths and distance between their rotation axes have been determined. Finally the measurement of the model is redesigned to make it possible for the production. A method is advised for calculating the extraterrestrial solar radiation amount absorbed on the system. And this method is executed for the projected model.Master Thesis The Use of Cell Polyurethane Foams in Air-Type Solar Collectors as the Heat Absorbing Element(Izmir Institute of Technology, 2006) Değirmencioğlu, Can; İlken, Zafer; İlken, Zafer; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyAfter the energy crisis in early 1970.s, the priority of alternative energy resources is expanded. There have been many researches, to increase the efficiency of solar energy utilization systems, for domestic and industrial usage since early 1980.s up to now. In many fields air-type solar collectors are applicable. They generally used in food industry to dry agricultural products, textile industry to dry fabrics and space heating. Drying grains (wheat, barley, maize, etc.), fruits (grape, fig, apricot etc.), vegetables, tea are examples for food industry. Greenhouse heating and hospital heating to obtain fresh air are examples of space heating. These examples show that improving their performance is indispensable for commercial acceptance. In this study, the open-cell polyurethane foam as an absorber material, placed in a south facing, flat plate air-type solar collector at fixed tilt angle and effect of this material on collector efficiency has been investigated. The collector designed specially, in order to get maximum heat gain from the useful solar intensity falling on the glazing and insulated to loose minimum heat from collector case and transfer channels. Collector is tested under the regulations of ASHRAE 93-1986 standard named .Methods of Testing to Determine The Thermal Performance of Solar Collectors.. Air passing through the collector has been provided by a fan. Tests are repeated with three air speeds 1.266 m/s, 1.5825 m/s and 1.899 m/s. Maximum average efficiency is calculated on 1.5825 m/s. Maximum average temperature difference of air between inlet and outlet sections observed on 1.266 m/s. Maximum outlet temperature that we get is on the same day with maximum average temperature difference.