Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Energy and exergy analysis of renewable energy utilization in cement production(01. Izmir Institute of Technology, 2025) Alaca, Pelin; Çağlar, Başar; Fard, Mousa MohammadpourGeleneksel çimento üretim yöntemlerine kıyasla daha yeşil enerji sistemleri alternatiflerini keşfetmek için çimento üretiminin enerji ve ekserji analizi çalışılmıştır. İki farklı yeşil enerji senaryosu dikkate alınmıştır. Temel senaryo geleneksel çimento üretimidir. İlk senaryoda atık rüzgar türbini kanatlarının pirolizi ve gaz türbini çimento fabrikasına entegre edilmiştir ve elektrik ihtiyacı gaz türbini tarafından karşılanmıştır. Aynı zamanda hammadde piroliz ünitesinin katı ürününden sağlanmıştır. Bu senaryo için sıcak akımları kullanmak üzere bir ön ısıtma sistemi düşünülmüştür. İkinci senaryoda, PEM elektrolizörü de çimento fabrikasına dahil edilmiştir. Burada kömürle değiştirilmek üzere PEM elektrolizöründen hidrojen üretilmiştir. Tüm senaryoların termodinamik modellemesi Engineering Equation Solver (EES) yazılımı aracılığıyla gerçekleştirilmiştir. Temel senaryonun enerji ve ekserji verimliliği sırasıyla % 61,60 ve % 20,21 olarak bulunmuştur. Termodinamik analiz dışında, özgül enerji tüketimi (SEC) ve CO2 emisyonları hesaplanmıştır. En düşük SEC, 1704 kJ/kg olan senaryo 1 ile elde edilmiştir. CO2 emisyonları, 0,219 kg CO2/kg çimento ile senaryo 2 için minimum olarak sonuçlanmıştır. Tüm bunlar göz önüne alınarak, daha yeşil ve daha az enerji tüketen bir sistem oluşturulmaya çalışılmıştır.Master Thesis Electrocatalytic isopropanol oxidation for direct organic fuel cells(01. Izmir Institute of Technology, 2024) Çetin, Yağmur; Çağlar, Başar; Şeker, ErolDünya üzerinde sürekli artan nüfus yoğunluğu ve buna eşlik eden enerji tüketim oranları nedeniyle, yenilenebilir enerji kaynaklarını bulma, bunları erişilebilir ve kullanıma hazır hale getirme ihtiyacı önemli konular gelmiştir. Son yıllarda, hidrojen taşıyıcıları ve yakıt hücresi sistemleri, geleneksel fosil yakıt türlerine bağlı enerji üretim sistemlerine iyi alternatifler olarak öne çıkmıştır. Bu çalışma için, hidrojen taşıyıcısı olarak izopropanol-aseton çifti seçilmiş ve reaksiyon kinetiği incelenmiştir. İzopropanolün elektrokimyasal oksidasyonu, yakıt hücresi uygulamaları ve enerji depolama cihazlarındaki önemi nedeniyle oldukça ilgi görmüştür. Bu tez içeriğinde, Pt/C, Cu/C, Pt-Cu(1:1)/C, Pt-Cu(3:1)/C ve Pt-Ru/C ticari katalizörleri kullanılarak izopropanolün elektrokimyasal oksidasyon davranışına odaklanılmıştır. Oksidasyon reaksiyonunun performansını iyileştirmeyi amaçlarken, her bir elektrokimyasal katalizörün aktivitesi, seçiciliği ve reaksiyon koşullarındaki kararlılığı farklı ortamların etkisi altında, alkali koşullarda incelenmiştir. Bu katalizörlerin elektrokimyasal performansı Döngülü Voltametri, Elektrokimyasal Empedans Spektroskopi ve Kronoamperometri analizleri ile değerlendirilmiştir. Sonuçlar, diğer Platin bazlı katalizörlere kıyasla daha yüksek katalitik aktivite ve daha düşük kinetik direnç gösteren Pt-Cu/C katalizörünün üstünlüğünü göstermektedir. Bu gelişmiş performans, Bakır'ın OH- türlerine olan güçlü afinitesine atfedilir ve bu da izopropanol oksidasyon hızını artırır ve genel elektrokimyasal aktiviteyi teşvik eder. Genel olarak, bu çalışma izopropanol elektrooksidasyonunun kinetiğine dair değerli bilgiler sağlayarak ve Pt-Cu alaşımının çeşitli elektrokimyasal sistemlerde verimli alkol oksidasyonu için umut verici bir katalizör olarak potansiyelini vurgular.Master Thesis Modellıng And Sımulatıon Of A Doubly Fed Inductıon Generator-based Wındturbıne Under Symmetrıcal Voltage Fault(2023) Çiçek, Elif Dilara; Akkurt, Gülden Gökçen; Altun, KeremWhen wind turbines, which convert wind energy, one of the renewable energy sources, into electrical energy, are connected to the electrical grid, it is of great importance to maintain grid stability. However, the variable nature of wind can pose certain challenges to system stability in wind turbine grid integration. Regulations in different countries require wind turbines to continue contributing to the grid in the event of a fault. In this thesis, the process of converting wind energy into electrical energy through a specific generator is described, and the behaviour of the turbine is simulated in the event of a symmetrical voltage fault. This thesis aims to develop a simulation model for a variable-speed doubly fed asynchronous generator-based (Dfig) wind turbine with a partially scaled frequency converter control using the field-oriented vector control method and to investigate its grid contribution ability under different conditions. The aim was to ensure torque control on the generator side and grid-side control. After the completion of the control system, the turbine's grid contribution ability was examined under short-term faults, and it has been shown that the system continues to contribute to the grid after the voltage drop. The modelling was performed using the Matlab / Simulink program, and the results were shared. In the last part of the thesis, the effect of a symmetrical fault on the rotor current is analysed by the Monte Carlo method.Master Thesis Manufacturing of Starch-Based Bioplastic From Waste Potato Starch by Extrusion and Energy Analysis of the Production(2023) Tıhmınlıoğlu, Funda; Gökyıldız, Yasemin; Alsoy Altınkaya, Sacide; Altınkaya, Sacide; Tıhmınlıoğlu, FundaPlastic materials are an essential part of our daily lives and annual plastic production is higher than 380 million tons with a 4% annual increasing rate. Since the 1950s, 8.3 billion tons of plastic have been produced, 9% of these plastics have been recycled, 12% have been incinerated and the rest 79% have been dumped to landfills. Therefore, the development of biodegradable polymers obtained from renewable raw materials has become a priority to reduce the environmental impact and dependency on fossil resources. Thermoplastic starch (TPS) is a starch-based bioplastic obtained by the disruption of the starch granules with thermal and mechanical forces in the presence of plasticizer. In this thesis, production of TPS from residual potato starch by extrusion was investigated. The extrusion trials were conducted in a single-screw extruder. Glycerol was selected as plasticizer and added to starch with 20, 30 and 40 wt.%. Extrusion temperature profiles were 50-90oC, 60-90oC and 70-90oC. The pretreatment conditions for the residual starch were drying to 10 wt.% moisture content and sieving with 131μm mesh size. Specific mechanical energy values ranged between 7.89 kWhkg-1 and 43.27 kWhkg-1. The optimum product formation was selected according to processability with lower energy consumption and mechanical properties as TPS303 which has 30 wt.% glycerol content and processed between 70-90oC. Specific mechanical energy consumption for TPS303 was found to be 23.78 kWhkg-1. The mechanical properties of TPS303 were 4.48 MPa tensile strength, 59.74 MPa Young's modulus and 57.33% elongation at break. Consequently, residual potato starch was found to be a promising raw material for thermoplastic starch production with proper pretreatment.Master Thesis Effects of Electrical Dynamic Response of Doubly Fed Induction Generator Type Wind Turbines on Their Mechanical Systems During Single and Multiple Faults(2023) Coşgun, Mert; Karadeniz, Ziya Haktan; Altın, MüfitIn the early stages of wind turbine technology, the focus was on the separate development of mechanical and electrical systems and research was carried out only in these areas. Today's modern wind turbine designs, which have reached megawatt sizes, continue to be more cost-effective and dependable for countries to achieve their renewable energy targets. In this direction, wind turbine research and development processes have now started to focus on both mechanical and electrical systems and their subsystem interactions. In this thesis study, it is aimed to investigate the effects of the response of electrical control systems on towers components during grid faults. A doubly fed induction generator is used for power generation and power systems including converters and control systems are modelled in MATLAB/Simulink. Simulations were designed in Simulink to test the grid-connected wind turbine model and the Fault Ride Through condition that causes voltage drops in the grid connection lines; the response of the control system and electromagnetic torque output in the relevant case were sent to the mechanical system analysis tool Horizonal Axis Wind Turbine Simulation Code 2 to observe the effects on the mechanical system. In Horizonal Axis Wind Turbine Simulation Code 2, the interaction of the main bodies against forces and limits is analyzed and the results are reported graphically. The state of the system without fault and data with the faults are analyzed comparatively. It has been observed that the reactions of the electrical power systems during grid failure influence the mechanical systems.Master Thesis Lithiation of Metal-Oxide Thin Film Layers on Zto/Ag Electrodes by Magnetron Sputtering for Electrochromic Devices(Izmir Institute of Technology, 2023) Deveci̇, Enver; Özyüzer, Lütfi̇; Ünal, UğurElectrochromism is a property of materials that undergoes a reversible transition from a colorless or transparent state to a colored state under the action of electric voltage or current. What makes electrochromic materials special is by controlling the voltage applied to the material. Among these electrochromic materials, metal oxides such as WO3 and NiOx are metal oxides that are frequently used. Electrochromic devices are devices that do not consume much energy and can save a lot of energy. A typical electrochromic device consists of five different thin film layers: an ionic conductive layer (electrolyte) and transparent conductive oxides (ZTO, ITO, etc.) are located between the main electrochromic layer and the secondary electrochromic layer.In this study, instead of the traditionally used transparent conductive electrode ITO, ZTO/Ag/ZTO (Z=Zn2SnO4) electrode with high optical transmittance and electrical conductivity was used, thus cost-effective and more efficient electrochromic devices were produced. Here, 3 layers of thin film (WO3,Ta2O5, NiOx) coating on Glass/ZAZ samples was grown by magnetic sputtering method at room temperature and the production parameters were optimized. Here, WO3 and NiOx are used as thin film electrochromic layer, while Ta2O5 is used as solid-state electrolyte. The electrochemical properties of the metal oxide WO3 and NiOx coatings used here were measured in 1 M LiClO4-PC electrolyte using a conventional three-electrode configuration. In the next step, to test the performance of WO3 and NiOx electrochromic films, Li-based liquid electrolyte was mounted on our electrochromic device (ZAZ/NiOx/Ta2O5/WO3/ZAZ), which has a five-layer battery-like structure and tested.Master Thesis Improvement of Indoor Air Quality in Classrooms Based on Age of Air Parameters and Fanger's Predicted Mean Vote Method(Izmir Institute of Technology, 2023) Yetiş, Ahmetcan; Karadeni̇z, Zi̇ya Haktan; Gökçen Akkurt, GüldenIndoor air quality in classrooms is an important research topic today. Studies have shown that poor or inadequate indoor air quality has negative effects on students' performance and active participation in classes. The aim of this study is to examine the local air velocity and air age parameters to determine the ventilation needs of crowded, but limited-sized classrooms that are not connected to a central ventilation system, and to investigate the applicability of ventilation systems that can provide adequate indoor air quality. In the study, a primary school classroom with a capacity of 30 students was examined. Ventilation requirement is determined per person according to "ASHRAE 62.1-2022" Standard and "Building Bulletin 101" directive. For ventilation of the classrooms, counter-fluid heat recovery ventilation units mounted embedded in the wall. It is aimed to reduce the total volume allocated for the ventilation device in the classroom compared to the use of a single device. To slow down fresh air entering the room at high speed and mix it before reaching breathing zone, blowing directions of the neighboring devices are intersected. With these information, a classroom model was created to be analyzed with the Computational Fluid Dynamics method. In addition, another classroom model was created for investigating personal ventilation scenario. By a comparative analysis, average air velocities, age of air values around heads of students and students' perception of indoor air quality according to Fanger's "Predicted Average Vote" method were investigated.Master Thesis Modelling and Controlling of Hybrid Energy Systems With Hydrogen Storage(01. Izmir Institute of Technology, 2023) Denizli, Osmancan; Çağlar, Başar; Altın, MüfitHybrid renewable energy systems are gaining more attention for the problems like Global Warming and high CO2 emissions. Another topic that increases its popularity is hydrogen. Because it is a very good alternative fuel. In this work, every component of a basic Hybrid Renewable Energy System (HRES) will be modeled and short-time simulations will be made for any transient response of individual components. MATLAB Simulink is used for every model and simulation. HRES includes a wind turbine, PV array, battery energy storage, and electrolyzer. The system is also grid-connected. Additionally, different control strategies are investigated, obtained, and created. Maximum Power Point Tracking (MPPT) algorithms for Wind Energy Conversion System (WECS) and PV array were conducted. A control algorithm that combines the battery and the PV array was made and necessary circuits were designed. An overall model for different sizes and operations is created. One-day-long simulations were made for 11 different cases. The user can alter the overall model for different turbines, PV modules, and battery sizes. The total amount of hydrogen produced, energy generation, and consumption were observed for every case.Master Thesis Modeling and Thermo-Economic Analysis of a Photovoltaic-Battery Hybrid Energy System: a Case Study in Yenikale Geothermal Heat Center(01. Izmir Institute of Technology, 2023) Uslu, Gökçe; Gökçen Akkurt, Gülden; Helvacı, Hüseyin UtkuWater is vital for agriculture accounting 50-70% of the total global use of fresh water for irrigation. Geothermal water as a renewable energy source is used to generate electricity, heat and cool. The remaining water can be desalinated to be used for agricultural irrigation. Energy demand of desalination systems is high and mostly rely on fossil fuels increasing cost and greenhouse gas emissions. Thus, renewable energy use in desalination process is increasing. Based on a research project, a pilot desalination system is installed in Yenikale Heat Center of Balcova-Narlidere Geothermal District Heating System to desalinate geothermal water and use for agricultural irrigation. The desalination system is powered by a solar PV system which meets energy need entirely in summer but only 30-50% in winter. The remaining energy need is supplied from the grid. The aim of this study is to maximize the utilization of solar energy for the desalination process while minimizing reliance on the grid. To achieve this objective, three different scenarios are analyzed based on three different solar radiation values of 2021 integrating a battery system. For each scenario; first, battery capacities and the number of PV panels are determined. Then, energy, exergy and exergo-economic analysis are conducted. The parameters calculated in economic analysis are net present value, payback period and cost of energy production. One of the main results obtained is the unit energy cost for solar driven desalination system 0.28 $/kWh which is in a good agreement with the literature (0.214-0.23 $/kWh).Master Thesis Catalytic Pyrolysis of Virgin and Waste Polyolefins(01. Izmir Institute of Technology, 2023) Çalık, Fatma Defne; Yıldız, Günay; Şeker, ErolThe fact that increasing plastic production and the mismanaged waste released to the environment put the ecosystem at risk. One of the most promising recycling methods developed within this framework has been pyrolysis. In this thesis, a model feedstock mi (No: 119N302). Thermal (batch and continuous) and catalytic pyrolysis (in-situ and ex-situ) techniques were applied to the polyolefins. Silica-alumina-based solid acid catalysts were produced with the simple sol-gel method to compete with commercial ZSM-5 (30) and ZSM-5 (50). Catalyst-to-plastic ratios between 1/100 and 1/1000 were used for in-situ, and 200 h-1 and 500 h-1 WHSVs were used for ex-situ mode. 57 wt.% pyrolysis oil was produced from the thermal pyrolysis of the virgin PO mixture in the batch system. In the ex-situ catalytic pyrolysis experiments by 500 h-1 WHSV and by ZSM-5, silica-alumina, and ZSM-5 supported silica-alumina, 36 wt.%, 56.6% wt.% and 45.2 wt.% liquid, and by 200 h-1 WHSV, 29.9 wt.%, 54.1 wt.%, and 57.9 wt.% pyrolysis oils were collected, respectively. The most successful test in terms of product composition was ES2 with 82.9% gasoline (8.8% BTEX), and 16.7% diesel-range hydrocarbons. The motivation was investigating whether it was suitable to produce liquid hydrocarbons, in the range of C5-C20, as a feedstock in the petrochemical industry. As a result, it has been proven that energy recovery was possible and sustainable by plastics recycling instead of using fossil fuels.