Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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Author: search.filters.author.İlken, ZaferHas files: Yes

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Now showing 1 - 6 of 6
  • Master Thesis
    Estimation of the Total Solidification Time of a Liquid Phase Change Material Enclosed in Cylindrical and Spherical Containers
    (Izmir Institute of Technology, 2003) Bilir, Levent; İlken, Zafer
    This study investigates the inward solidification process of a phase change material (PCM) encapsulated in a spherical and cylindrical container with a third kind of boundary condition as well as the complete solidification and complete charging time of a cool storage tank which consists of spherical containers filled with a PCM.The phase change problem inside the containers is modeled in spherical and cylindrical coordinates and solved numerically by using enthalpy method with control volume approach. Computer programs are written in Basic language to determine the dimensionless total solidification time of the PCM held in a spherical and cylindrical container. These programs are run many times by varying the affecting parameters to obtain data sets of the dimensionless total solidification time of PCM. These data sets are then used to derive correlations which express the dimensionless total solidification time of the PCM in terms of the affecting parameters by applying multiple regression analysis.Another program is written to simulate a cool storage tank with spherical containers. The complete solidification and complete charging time of the tank are calculated by using this program. A parametric study is realized for the cool storage tank by varying the design parameters and the influence of these variations on the complete solidification and complete charging time is investigated.
  • Master Thesis
    Numerical Analysis of Finned Downhole Heat Exchangers: a Parametric Study
    (Izmir Institute of Technology, 2002) Alpay, Selda; İlken, Zafer
    This study investigates the performance of an U-type Downhole Heat Exchanger (DHE) with a new pipe arrangement, where circular fins are fitted around the legs of the DHE.In the present work the heat transfer performance of optimized DHE with circular fins is investigated and compared with that of optimized with bare type DHE. This study numerically models a well with a DHE to determine the heat flow that can be extracted by the DHE. A DHE program is written in BASIC language to investigate the heat transfer rate both for bare and finned type DHEs. In order to verify the accuracy of this program comparisons are made with an experimental work for bare type DHEs. Also a computational fluid dynamics program, FLUENT, is used to study fluid and heat flow processes in the well and DHE systems. The results of the FLUENT program are also used to compare the DHE program. The simulations carried out also enable us to determine the influence of the design parameters of the finned type DHEs. Some examples of optimized geometries are finally shown and discussed.
  • Master Thesis
    Resevoir Simulation of Balçova Geothermal Field
    (Izmir Institute of Technology, 2004) Budak, Barış; İlken, Zafer
    This study investigates the geothermal reservoir of Balçova geothermal field using the program Fluent which is written for general problems of fluid flow and heat transfer in a given complex geometry. Geothermal reservoir simulation of Balçova geothermal field is made by Istanbul Technical University, Department of Petroleum and Natural Gas Engineering using the program Though2 which is written for geothermal reservoir application in 2001. The results of this study become a starting point of this thesis. Besides, the new techniques applied the geothermal field since that period, and reinjection of the geothermal fluid by the well BD-8 to the reservoir, made it necessary to remodel of the field. During the modeling study, the conceptual model of the field is developed based on technical data and advices by the Balçova Geothermal Ltd. The fault Agamemnon-I existing in the field is thought the dominated fault of the reservoir and assumed that the heated water from the aquifer is raised to the surface using that fault as a flow path. The geometry of the conceptual model of the reservoir is drawn and meshed properly using Gambit meshing program and meshed reservoir is exported and run in Fluent program under given boundary conditions and after that 3-D temperature distribution of the reservoir is obtained.
  • 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
    In 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
    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
    After 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.
  • Master Thesis
    Design and Optimization of a Zero Energy Building
    (Izmir Institute of Technology, 2004) Gediz, Gamze; İlken, Zafer
    Izmir Institute of Technology (IZTECH), founded in 1992, is the third state university of Izmir. The campus area has the renewable energy sources of several kinds. The aim of this thesis is to design and optimize a building, which produce its own energy by using these sources.Gülbahçe Zero Energy Building (GUZEB) is designed as a library and a gallery, and to be used for symposiums and special day meetings. 32oC geothermal water that is from the ancient cave, which is located in campus area and close to the location of the building, will be used for heating and to meet the hot water requirement of the building. Floor heating system considered being the best heating option with 32oC water source. Necessary pipe length for floor heating system is found by using the software FLUENT.Necessary cooling load is calculated in two different ways by with and without hourly load distribution. With hourly load distribution cooling load calculation is made by using Alarko-Carrier .s HVAC Design Hourly Analysis Program.Additionally, energy storage method is recommended for the cooling plant, which will meet the cooling load. With this method, smaller cooling plant can be chosen instead of choosing cooling plant, which meets the load of symposium days or special day meetings that both are rare. Because of this, electrical load of the cooling plant considered to be lower.Silica-aerogel and many different isolation materials are used in the design of building.s isolation. Fiber lighting is recommended to decrease the lighting load of the building and with automatic controlled curtains and panels; daylight can be controlled during the summer days. So, electric consumption of the building can be tried to be decrease. The wind speed of the location is 5-7 m/s. Electric demand can be met with the photovoltaic panels and wind turbine that will be located in suitable position.