Master Degree / Yüksek Lisans Tezleri

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

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Subject: search.filters.subject.Thermal performance

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  • Master Thesis
    Numerical and Experimental Investigation of Thermal Performance of Graphene Reinforced Aluminium
    (01. Izmir Institute of Technology, 2020) Yılmaz, Ahmet Berk; Toprak, Kasım; Kandemir, Sinan
    Graphene is a material with superior properties such as high thermal conductivity and mechanical strength. These exceptional properties make graphene a good candidate for being used as a reinforcement agent in other materials. Aluminium is a widely used material in industry for thermal applications for being cheap, lightweight and having high thermal conductivity. In the literature, there are many examples of graphene reinforced aluminium production. Also, the effects of graphene on thermal conductivity and mechanical properties of aluminium are also investigated experimentally. However, there are limited molecular dynamics studies for graphene-aluminium composites. In this work, aluminium, graphene and graphene coated aluminium are modeled and simulated with non-equilibrium molecular dynamics method. Length, width, height, temperature dependence of thermal conductivity of these models are investigated. In addition, effects of graphene layer number, defect size and defect locations are also reported. Additionally, an experimental setup is designed and produced for a comparative study. Thermal performances of aluminium alloy and graphene nanoplatelet reinforced aluminium are investigated with a convection heat transfer test.
  • Master Thesis
    Numerical Analysis of Thermal Performance of Glazing Systems
    (Izmir Institute of Technology, 2019) Şahin, Yağmur; Başaran, Tahsin
    Thermal performance of different glazing systems have been investigated with a comprehensive parametric study numerically. In order to analyze the heat transfer through the windows, CFD simulations have been performed considering many affecting parameters. The aim of the study is to determine the appropriate window configurations according to the different cities that have different climatic conditions of Turkey which are: Ağrı, Sivas, Amasya and İskenderun. For this purpose, the glazing part of the window has been analyzed because of having low thermal resistance due to the gap widths, temperature differences and the emissivity values. Four physical models of glazing systems were designed. The thickness of glazing units is 4 mm and the height is 1 m as a constant. For investigating the effect of the cavity dimension on the heat transfer, two gap widths usually used, are determined and combined in different ways which as 12–12 mm, 16–16 mm, 12–16 mm and 16–12 mm. Different boundary conditions are defined according to ambient temperature of inside and outside. Radiation heat transfer is included in the calculations and various low-e coatings are defined to analyze the radiation effect on the heat transfer coefficient. As a result of this study, temperature and velocity profiles are different in all scenarios. The effect of gap width on the U-value is more distinguished in the low temperature difference. Heat loss can be minimized significantly with using low-e material and the emissivity value is more effective on the wider gap widths. It is also shown that the optimum air layer thickness of the triple pane window differ from the temperature difference significantly. The highest U-values were obtained in 12-12 mm gap width glass. It was determined that the heat losses can be reduced by using 16-12 mm gap width glass about 2% and 8% in cold regions and in warm regions respectively.
  • Master Thesis
    Improvement of the Thermal Performance of an Aluminium Window Frame With Cfd Analysis
    (Izmir Institute of Technology, 2019) Gökçen, Gökçe; Başaran, Tahsin
    Most of the primary energy used in the world belongs to fossil fuels. Energyefficient activities are carried out in many different sectors in order to prevent the depletion of the reserves of these resources. The building sector is one of them and many different studies are being carried out to reduce the energy consumed in the buildings. Windows are the main unit of heat losses and gains in buildings. In literature, the main reasons for heat losses through windows are usually stated as glass units due to their large areas and relatively higher overall heat transfer coefficient. However, windows frames are as important as glass units because they also have higher heat transfer. Since the most commonly used material in window frames, which is aluminium, has the highest thermal conductivity value, this topic should be investigated. In this study, two different strategies are presented to improve the thermal transmittance of an aluminium frame without changing the frame geometry. The first strategy presented is the improvement of the gasket and thermal break materials in which high thermal conductivity materials are used which have a considerable impact on the thermal performance of aluminium window frames. The second strategy is to fill the cavities in aluminium profiles with polyurethane foam in order to reduce convection effects. Two dimensional CFD simulations of the aluminium window frame, modelled with information from the manufacturer, were used to investigate these improvement strategies. As a result of the study, the importance of thermal break and gasket materials used in the aluminium window frame has been seen and the thermal conductivity of these materials has a considerable effect on the thermal performance of the windows. Moreover, the polyurethane foam filled air cavities in the aluminium frame have positively affected the thermal performance of window as proposed and %29.44 improvements occurred.