Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Kinetics of Silica Polymerization at Various Conditions(01. Izmir Institute of Technology, 2022) Baba, Alper; Demir, Mustafa Muammer; Demir, Mustafa Muammer; Baba, Alper; 03.03. Department of Civil Engineering; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologySilica is the most abundant element on Earth because the Earth's crust is composed mainly of metal silicates. The source of this silica is mainly volcanic rocks, which come to the surface through tectonic activity and are the primary source of heat for geothermal activity. The silica concentration in a geothermal fluid is higher than the solubility limit of natural waters, so scaling of (metal) silicates is often observed in geothermal operations. This situation has become critical for geothermal power plants. Since silicates have an insulating structure, they lead to a reduction in energy efficiency during fluid transport. The formation of silica-rich deposits should be understood to minimize the negative effects of the scaling. Briefly, silicic acid molecules in the reservoir system are condensed, and the monomeric silicic acid molecules bind to each other via covalent bonds. In the course of this reaction, dimers, tetramers and short oligomers are formed, and eventually a large polymeric silica network is formed. In the presence of metals, both the kinetics of polymerization and the structure of the network are inevitably affected. In this study, the presence of kinetic parameters (different salts such as FeCl3, MgCl2, AlCl3 and NaCl), the reaction process, the rate and the activation energy of silica polymerization at different temperatures between 25 and 90 °C were investigated. The yellow silicomolybdate method was used to determine the concentration of monomeric silica. The order of the polymerization reaction was given as 3. The polymerization occurs in the initial phase, in the first 40 minutes, where the activation energy was about 29.52 ± 2.28 kJ/mol and the rate constant was of the order of 4x10-8 mol-2∙L2∙s-1. The results also confirmed that pH has a stronger effect on the kinetics of silica polymerization than temperature. The neutral solution decreases rapidly, while the acidic solution has an induction phase in the first hour of polymerization. Different temperatures did not affect the polymerization rate as much as pH. At 25°C the experiment showed the fastest polymerization, but at 90°C the low concentration changed from the beginning. During all these experiments, no scaling of amorphous silica was observed, only the polymerization of silica.Master Thesis Evaluating the Impacts of Geothermal Energy Plants on Quality of Life: Case of Alasehir (manisa)(01. Izmir Institute of Technology, 2021) Velibeyoğlu, Koray; Velibeyoğlu, Koray; 02.03. Department of City and Regional Planning; 02. Faculty of Architecture; 01. Izmir Institute of TechnologyQuality of life has been handled with different approaches by many disciplines from past to present, and it has started to be used frequently in the international agenda in order to meet the needs of the increasing world population and to find solutions to problems such as climate change. Due to the multidimensional and complex nature of the concept, there is no consensus on the definition and measurement method. Quality of life definitions, and indicators varies in the context of scale, approach, and method. The study concentrates on the perceived quality of life of people close proximity to geothermal power plants in the case of Alaşehir. First, the indicators used in neighbourhood, rural and environmental quality of life studies were examined and grouped under the parameters of built environment, accessibility, vulnerability, degradation, health, contamination, and resilience. Then, the historical background, usage, geothermal systems, environmental impacts and social acceptance of geothermal energy and geothermal energy studies in Turkey were evaluated. As a result of this evaluation, the participation parameter was added to the research. In line with socio-spatial analysis, the areas under the influence of geothermal power plants were determined and semi-structured interviews were conducted with the parameters. As a result of the analyses and interviews, it has been determined that the impact of geothermal energy on the quality of life in Alaşehir district is perceived through agricultural production. Contamination, vulnerability, and participation parameters come to the fore, and show that geothermal power plants negatively affect the perceived quality of life.Master Thesis A Case Study on Settlement Analysis of Geothermal Power Plant Foundation(01. Izmir Institute of Technology, 2018) Elmas, Hakan; Elmas, Hakan; Ecemiş Zeren, Nurhan; 03.03. Department of Civil Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyFoundation settlement criteria are highly sensisitive for geothermal power plants. In geotechnical literature there are several settlement analyses which can be done by using elastic approaches, in-situ test results or numerical methods. Unfortunately, all these methods cannot give close results with each other. As a result, the unrepresentative analyses influence the safety, economy and time of the projects. In this study, the settlement of the geothermal power plant located in Aydın / İncirliova which constructed on a raft foundation was investigated. According to soil investigations, the raft foundation is located on multilayer soil profile and a compacted high qualified fill layer is placed under the raft foundation. Soil parameters were obtained from in-situ tests (standard penetration tests, cone penetration tests, pressuremeter tests and plate load test and) and laboratory experiments. Settlement results were obtained by 1D stress – strain analyses and 3D continuum numerical analyses (Hardening Soil Model with Small Strain Stiffness and Mohr Coulomb Soil Model) using the commercially available Settle 3D and Plaxis 3D software, respectively. The results of these analysis were also compared with the field monitoring data. The results show that Hardening Soil Model with Small Strain Stiffness gave more accurate result than other models due to the representation of real soil behavior, obtaining non-uniform stress distribution of foundation and obtaining effective stress depth accurately for settlement.