Master Degree / Yüksek Lisans Tezleri

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

Browse

Filters

2006 - 200912010 - 201922020 - 20234

Settings

Subject: search.filters.subject.Geothermal energy

Search Results

Now showing 1 - 7 of 7
  • Master Thesis
    Response of Vertically Loaded Energy Piles Under Earthquake Excitation
    (2023) İnayet, Mehmet Göktuğ; İşbuğa, Volkan
    Pile foundations are deep foundation systems that are used to transfer loads from superstructure to soil by either resisting surface friction or reaching a deeper and stiffer soil layer when geotechnical properties of the soil site are not sufficient to carry the loads transferred from superstructure. Energy piles fulfill the same function along with the ground heat exchanging via heat pump systems, thus satisfying the energy demand of a building for heating-cooling operations. This feature of energy piles draws attention as an innovative system supplying a renewable energy resource. However, heat exchanging operations of energy piles cause temperature variations on pile and the surrounding soil which may cause additional load and deformations. Moreover, temperature variations may affect the elasticity modulus of soils and shear strength of cohesive soils. In this study, earthquake response of an axially energy loaded pile was investigated considering the heating effect under 2020 Izmir earthquake motion using finite element method and compared to the those of identical regular piles. We performed analyses with different soil types, geometric properties, and temperature magnitudes under steady-state heating. Based on the analysis results, heating effect on pile head stiffness with respect to geometric properties were obtained. Two important conclusions have been made; (i) the most critical effect on heating depends on mechanical loading condition of pile and thermal expansion coefficient of soil, (ii) geometric properties may affect the temperature distribution resulting in an unforeseen change in pile head stiffness.
  • Master Thesis
    Energy, Exergy and Enviromental Assessment of a Novel Multi-Generation System Fed by Biomass and Geothermal Energy Sources
    (01. Izmir Institute of Technology, 2022) Şeker, Utku; Gökçen Akkurt, Gülden; Mohammadpourfard, Mousa
    Energy is the one of the critical tools that ensure the development of the countries. Since almost no country is completely energy independent, it is very important for countries to use the available energy efficiently and to produce their own energy from renewable energy sources. Multi-generation systems combine various cycles and processes to produce number of outputs and valuable market products using one or multiple energy sources as input. By creating a multi-generation system powered by renewable sources can increase system efficiency and provide some additional outputs such as hydrogen, heating, cooling, and domestic hot water. In this thesis, a novel multi-generation system consisting of a biomass gasification cycle, a double-flash geothermal cycle, an Organic Rankine Cycle and a PEM electrolyzer subsystems, is proposed to increase the efficiency and energy production from biomass and geothermal energy sources instead of using a single source for a single output. The proposed system is analyzed in terms of energy, exergy, and environmental impact point of view. By performing parametric studies for biomass flow rate, turbine inlet temperature, and single-objective optimization, effects on thermodynamic behavior and environmental impact are investigated for subsystems and overall system. The best operating conditions are determined. The findings indicate that energy efficiency of the proposed multi-generation system is 75% higher than a double-flash geothermal power plant. Based on the parametric study, biomass mass flow rate is encountered as the most significant parameter, which caused an 11.7% increase in energy efficiency, and 225% increase in environmental impact cost.
  • Master Thesis
    Energy Performance Analysis and Materials Characterization of Aerogel Insulation Blankets
    (Izmir Institute of Technology, 2022) Alan, Selena; Gökçen Akkurt, Gülden; Akkurt, Sedat
    İzmir Geothermal Energy Inc. is a geothermal district heating company in İzmirTurkey that circulates hot water throughout the district via a 450 km of piping system and with the help of valves, pipes, and heat exchangers. As the distance traveled by the hot water is excessively long, heat losses are common. Rock wool is used as thermal insulation material, but the performance degraded over time because of water leakage. Instead of rock wool, aerogel insulation blanket use is evaluated in this study. Rock wool and three different aerogel insulation blankets are comparatively studied to assess their structures and thermal performances in two ways: the first is the characterization of materials by various physical and chemical analysis methods in the IZTECH-Integrated Research Center. The second way is to assemble a test setup on-site and make thermal measurements on the test setup for each aerogel insulation material, rock wool, and bare pipe. Heat loss calculations were conducted by EES software. The results are compared based on each characterization and thermal performance calculation. The thermal conductivity values of the insulation materials were calculated. Nonwetting properties were also checked to understand their hygrothermal properties. Compared with bare pipe, with the 10 mm thickness, rock wool decreases heat loss by 48-52%, and with the 10 mm thickness, the aerogel insulation blankets reduce heat loss by 57-61%. Finally, while aerogel insulation blankets have a better performance, they are more expensive than rock wool.
  • Master Thesis
    Development of a New Antiscalant for Minimization of Stibnite Scaling in Geothermal Binary Plants
    (01. Izmir Institute of Technology, 2021) Karaburun, Emre Mustafa; Baba, Alper; Demir, Mustafa Muammer; Demir, Mustafa Muammer; Baba, Alper
    Demand for renewable and sustainable energy resources has been increasing in recent years due to the adverse effects of fossil energy resources (gases, oil, coal ect,) on human health and nature. Since geology properties of our country is rich in geothermal energy resources, there is a remarkable increase in plant capacities every year. Geothermal energy is the energy obtained from the fluid, gas, and steam that have been stored in reservoirs by carrying the heat energy accumulated in the rocks in the depths of the earth or surfaced along the discontinuity zones.The increase in the use of geothermal energy and the increase in the capacity of the power plants has also revealed the problem of scaling. The main cause of deposition are the decrease in solubility of minerals by a decrease in pressure and temperature upon pumping the geothermal brine up to the ground. Calcium carbonate, calcium sulphate, metal silicates (Mg, Fe) are the most widely accepted types of scaling. In recent years, antimony and arsenic sulfide scaling have been encountered in volcanic and metamorphic regions. Between these two types of scaling, antimony sulfide is mostly seen in the heat-exchangers and preheaters where the temperature drops suddenly. In this thesis, the antimony sulfide scaling formed in the geothermal power plant was synthesized in an autoclave reactor under specified conditions. Water-soluble polymers nominee for being antiscalants such as Poly (vinyl sulfonic acid), Poly (acrylamide-co-vinyl sulfonic acid), Poly (acrylamide-co-vinyl phosphonic acid), Alginic Acid, Natural antiscalants, Polyacrylic acid, and Polyvinyl alcohol were employed. The results suggest that polymers containing vinyl sulfonic acid and acrylamide likely shows remarkable progress in increasing the concentration of ions in decantate, particularly at low dosages. (≈5 ppm)
  • Master Thesis
    Effectiveness in Space and Energy Utilization in Hvac System Selection
    (Izmir Institute of Technology, 2019) Elbiz, Gizem; Başaran, Tahsin
    In Turkey, energy consumption for heating constitutes an important part of the total energy consumed. The choice of heating system and the preferences in the use of related energy sources, excessive energy consumption and environmental impact cause high costs and significant area losses. A large number of parameters must be evaluated for the correct system selection. These parameters determine the installation cost of the system, heating and cooling loads during the construction period, and the environmental impact of energy consumption. This study aims to obtain the most economical and environmental friendly energy resource in a housing structure and accordingly, heating system and the system spatial value. The use of fossil fuels such as coal, fuel oil and natural gas and the geothermal energy as a renewable energy source are planned to be investigated. The analysis was carried out on how the climate conditions and economic values of the provinces of İzmir, Balıkesir, Kütahya and Ağrı, which are located in different climatic regions will be effected and where direct use of geothermal energy is concerned, will affect the results of the different system usage. Life Cycle Cost assessment was performed to investigate the relationship between the initial investment in a housing structure and the use of energy source and system selection. Geothermal energy is the best source of energy both for installation and renewal and for fuel consumption and environmental purposes. Geothermal heat exchangers selected for the source take up 36 times less space than coal boilers, and the economic reflection of this area is approximate 8000 if given the example of İzmir province. While considering the environmental impacts, CO2 emissions of geothermal energy are 15 times less than natural gas and 50 times less than coal.
  • Master Thesis
    Thermodynamic Optimization of Downhole Heat Exchangers for Geothermal Power Generation
    (Izmir Institute of Technology, 2016) Parmanto, Slamet; Gökçen Akkurt, Gülden; Yıldırım Özcan, Nurdan
    Geothermal reservoirs have various thermodynamic and physical properties. The heat extraction and power generation from the geothermal reservoirs depend on the reservoir properties. Downhole heat exchangers (DHEs) are designed to move the heat extraction process into the geothermal well. The working fluid is injected to the DHE which suspends in the geothermal well, heated by geothermal fluid and then returned to the surface through the inner pipe. DHEs have been used for heating purposes widely but there is no application for electricity generation. Because of the natural convection on the geothermal fluid side, convective heat transfer coefficient is low and simultaneously the heat extraction rate is low comparing with extracting geothermal fluid by downhole pumps. Therefore if the temperature is high but flowrate is low in a geothermal well, DHEs are good alternatives to harness the energy from that well. Considering the number of wells with abovementioned conditions in the World, there is a potential for electricity generation coupling geothermal power plants with DHEs. The main purpose of the Thesis is to develop a thermodynamic and economic evaluation model of DHEs for power generation and to examine the feasibility of the model. The thermodynamic model is developed by EES software and over 300 simulations have been conducted to identify the effects of the insulation, geothermal well conditions, geometry of DHE, mass flowrate and the type of working fluids to the performance of DHE system. The economic analyses are conducted to evaluate the thermodynamic results regarding the economic consideration such as Net Present Value (NPV), simple payback time and electricity production rate. The results show that the insulation on the inner pipe is desirable to prevent heat loss along DHEs. The best design of the DHE is a design with deeper the depth, larger the diameter of the inner pipe, and higher mass flowrate for a specific geothermal heat source. The best design for the case study resulted as a work output of 3152 kW with annual net revenue and payback time of $1.75 million and 2.24 years, respectively. Besides, the economic evaluation gives positive value for NPV which means investment in DHE for geothermal power generation is acceptable.
  • Master Thesis
    The Economic Analysis of Geothermal / Absorption Cooling of a Hospital: Case Study of Dokuz Eylül University Research and Application Hospital
    (Izmir Institute of Technology, 2006) Altın, Mete; Gökçen Akkurt, Gülden
    Dokuz Eylül Research and Application Hospital, founded in 1982, is located in İnciraltı Place, in Balçova. It is placed at the south of İzmir and between the İzmir-Çeşme Highway and İzmir-Çeşme Super Highway. Rather rich geothermal resources found in Balçova, provides the use of geothermal water for heating in the hospital. However, the required cooling capacity for the hospital, which is relatively massive when compared with the residents, has been supplied by conventional compression chillers. In this study, the aim is to decrease the overall annual costs incurred by cooling of the hospital by implementing an absorption cooling system, which uses geothermal fluid as the heating source. The main idea behind this implementation is that the electricity consumption of an absorption chiller is minimal when compared with a compression chiller. On the other hand, since the source that is going to be used in the system is geothermal energy, there will be an additional cost incurred by the use of geothermal fluid. So, the economic analysis that is going to be conducted involves the comparison of two alternatives, which are leaving the system as is now and implementing an absorption cooling system. To minimize the costs incurred by the implementation of an absorption cooling system, instead of supplying the full capacity of the hospital, a moderate capacity will be supplied by the absorption chillers, by using the existing compression chillers as the peaking units. Since it is not known which capacity will be suitable for the needs, several absorption cooling machines with various capacities will be examined. After comparing these mutually exclusive alternatives, the effect of the change in geothermal fluid price on the implementation of an absorption cooling system, and the break-even geothermal water price will be found. At the end, the investment worth values of the selected absorption cooling machines will be examined to decide whether to implement an absorption cooling system in the hospital or not.