Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Thermal Performance of Graphene Coating on Copper(Izmir Institute of Technology, 2019) Ersavaş, Gizem; Toprak, Kasım; Çelebi, Cem; Toprak, Kasım; Çelebi, CemOver heat is always a problem for electronic devices because the locally generated heat cannot be transferred appropriately to the corresponding heat sink fast enough. This situation leads to affect materials’ structures, mechanical properties and conductivities badly. In order to avoid this problem, high thermal conductivity materials are used to dissipate the heat quickly. Thanks to the development of technology, the size of the electronic devices is reduced day by day. This also shrinks the size of the interconnect components. So this situation leads to researchers to investigate nano-sized interconnect components and copper, which is a widely used material, is one of them. Copper is one of the preferred metals for electronic devices because of high thermal conductivity, easy processability, and high use in daily life and industry. For example, copper components, which is used in electronic, are getting so thin and must carry so much current. And that causes to increase friction. Thus heat is occurred. Consequently, cooling problems have arisen. And if the material’s cooling problem won’t be solved then the material can be damaged. It is thought that to overcome this problem, coating with a high thermal conductivity material such as graphene, the thermal conductivity can be improved. In this study, thermal performance of graphene-coated copper were investigated numerically and experimentally. This study consist of two main sections. The first part, MD simulation code was created using C++ programming language to investigate thermal conductivity of copper, different number of graphene layers and these graphene layers were coated on copper in different length, width, height and temperature. In the second part, the thermal performance of pure copper, annealed copper, a layer of graphene-coated copper, and multilayer graphene-coated copper was studied by the experimental setup at three different temperatures and volume flow rates.Master Thesis Zeolite Based Composites in Energy Storage(Izmir Institute of Technology, 1999) Negiş, Fikri; Ülkü, SemraIn this thesis, second phases were used for the zeolite-based composites with high thermal conductivity for energy storage applications. Natural zeolite, clinoptilolite received from large deposits in Turkey was used as matrix while aluminum, aluminum hydroxide and graphite were used as second phases for composite preparation.Composites of different compositions (from 10 to 40 wt% additive loading) were prepared by mixing different amount of second phases to the clinoptilolite.Powder mixtures were pelletized using poly vinyl alcohol as a binder. The use of the binder was necessary to obtain mechanically strong pellets. The thermal treatment temperature and press pressure were determined as 150°C and 60 bar for the pellet preparation. Powders were further characterized by thermo gravimetric analysis, differential thermal analysis and differential scanrung calorimetry. These characterizations have shown that three types of water is present in clinoptilolite: external water, loosely bound water and tightly bound water.Thermal conductivities of these composite pellets prepared were determined using hot plate method.Thermal conductivity of pure matrix cIinoptilolite pellets were measured as 0.26 W/mK. Thermal conductivity increased significantly by using aluminum as the second phase while it did not change much for graphite and aluminum hydroxide composites.For composites containing 40% aluminum or aluminum hydroxide or graphite, thermal conductivities of 1.18, 0.50, 0.43 W/mK were measured, respectively. Aluminum containing composites could be used as adsorbent bed materials and by this way, it may increase the performance of adsorption heat pumps.