Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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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, Uğur; 01. Izmir Institute of TechnologyElectrochromism 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; Gökçen Akkurt, Gülden; Karadeni̇z, Zi̇ya Haktan; Gökçen Akkurt, Gülden; 03.06. Department of Energy Systems Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyIndoor 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 Experimental Investigation and Computational Fluid Dynamics (cfd) Analysis of Geothermal Sourced Hot Air Drying(Izmir Institute of Technology, 2022) Helvacı, Hüseyin Utku; Gökçen Akkurt, Gülden; Gökçen Akkurt, Gülden; Helvacı, Hüseyin Utku; 01. Izmir Institute of Technology; 03.06. Department of Energy Systems Engineering; 03. Faculty of EngineeringDrying is one of the oldest methods used to increase the product's shelf life and reduce transportation costs, consisting of heat and mass transfer between the product and the surrounding environment. One of the most common drying methods is hot air drying. The most critical parameters in hot air drying processes are drying air temperature, air velocity and relative humidity. Renewable energy resources can be used as heat/electricity in drying processes. Geothermal energy resources are highly suitable for hot air drying with their temperature compatibility and reliability. The geothermal resources in Turkey have a high potential for hot air drying. This Thesis examines tomato slices' quality parameters at different drying air temperatures and velocities. A cabinet-type geothermal sourced hot air dryer is installed in the Yenikale Heat Center of the Balcova-Narlidere Geothermal District Heating System in Izmir-Turkiye. Drying experiments are carried out at 40-60-80°C air temperatures and 0.5-1.5 m/s air velocities to examine their effects on drying kinetics and quality of dried tomatoes, such as pH, color, and moisture. With the help of the data obtained, drying time, drying rate, moisture rate, and effective diffusion coefficients are determined, and dimensionless moisture rate is modeled using thin layer models. Also, energy and exergy analyses are made for each experiment. Finally, experimental and simulation results are compared by using CFD to perform experimental design. The simulations created by using CFD are obtained in a much shorter time and more accurately since all materials used for the experiment are idealized.Master Thesis Statistical Analysis of the Effect of Meteorological Parameters on Pm10(Izmir Institute of Technology, 2022) Gökçen Akkurt, Gülden; Turhan, Cihan; Gökçen Akkurt, Gülden; Turhan, Cihan; 03.10. Department of Mechanical Engineering; 03.06. Department of Energy Systems Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyAir pollution is a serious threat where the pollutants in the air in solid, liquid and gaseous states reach levels that would harm the natural balance of the environment and the lives of vital organisms. Especially in industrialized cities, in addition to the effects of urbanization, physical environment characteristics may also play a role in the formation of environmental problems. Therefore, it is of high importance to understand the characteristics of the natural environment in the studies on air quality, in order for urban spaces to be livable areas. In this study, the correlations between PM10 pollutant data and certain meteorological parameters that were obtained from 3 stations in İzmir province were statistically evaluated. PM10 data was studied according to pre-pandemic, mid-pandemic and post-pandemic periods between 2017–2021. Meteorological data was gathered for a twelve-month period between February 2021 and January 2022 and its effect on PM10 data for the same period was analyzed. In the statistical analysis that was performed via Minitab software, hourly average data of PM10 was the dependent variable; temperature, relative humidity, and wind speed and direction were the independent variables. In the analysis that Pairwise Pearson Correlation Coefficient (r) was used, the most significant correlation was found to be between relative humidity and wind speed.Master Thesis Coupled Wake and Blockage Modelling for a Wind Farm(Izmir Institute of Technology, 2022) Bingöl, Ferhat; Bingöl, Ferhat; 03.06. Department of Energy Systems Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyOne of the significant reasons for the power loss in wind farms is the wake effect. Therefore, the wake effect is crucial for designing a wind farm. However, only wake modeling is not sufficient to explain power losses. Wake is the turbulent, complex, and relatively weak flow behind the wind turbine. The wake effect is not required for the front row turbines in wind farms, and the wake model cannot be applied. It is assumed that the wind farm directly encounters the free stream wind speed. However, the blockage effect, also known as the induction zone effect, is observed at the front of the wind turbines. Due to this effect, the wind farm encounters a lower wind speed than the free-stream wind speed. This situation reduces the accuracy of the Annual Energy Production (AEP) calculation in wind farms. The motivation of this study is to obtain an improved coupled wake and blockage model that converges to the accurate SCADA data of a wind farm more than the wakeonly or blockage-only models. This study applies seven wake and six blockage models to the wind farm. The similarities and differences between the coupled models and the wind farm SCADA data and their reasons are discussed.Master Thesis Energy Performance Analysis and Materials Characterization of Aerogel Insulation Blankets(Izmir Institute of Technology, 2022) Akkurt, Sedat; Gökçen Akkurt, Gülden; Gökçen Akkurt, Gülden; Akkurt, Sedat; 03.09. Department of Materials Science and Engineering; 03.06. Department of Energy Systems Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technologyİzmir 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 Computational Fluid Dynamics (cfd) Analysis of Latent Heat Storage in Heat Exchangers by Using Phase Change Materials (pcm)(Izmir Institute of Technology, 2020) Çetkin, Erdal; Çetkin, Erdal; Rocha, Luiz Aberto Oliveira; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe development of TES applications and materials takes the attention of many researchers, but the current literature rarely involves studies concerning medium temperature applications. This thesis compares available phase change materials (PCMs) for the medium temperature range. For this aim, Erythritol was defined as PCM in the numerical analyses. The effect of heat transfer fluid (HTF) tube position and shell shape on the melting time and sensible energy requirement for melting a phase change material (PCM) in a latent heat thermal energy storage (LHTES) application were investigated. Tube location and shell shape are essential due to the shape of the melted region, i.e., similar to the boundary layer. Results show that the S-curve of melting becomes steeper if the tubes are distributed such that the intersection of melted regions is delayed. Therefore, melted regions should be packed into a finite space which uncovers the shape of the shell that minimizes melting time and required sensible energy. Results show that, rectangular-shaped shell design where the tubes located near the bottom end decreases melting time and sensible energy from 67 minutes to 32 minutes and from 161.8 kJ/kg to 136.3 kJ/kg for %72.3 liquid fraction relative to the circular-shaped shell, respectively. In the four-tube cases, then the required melting time and sensible energy decrease 80% and 3.8% through the rectangular-shaped shell design for the PCM to melt completely, respectively. Overall, the results show that sensible energy storage and especially melting time can be decreased greatly by just varying the design.Master Thesis Wind Turbine Power Curve Update Based on Atmospheric Conditions and Structural Fatigue(Izmir Institute of Technology, 2020) Bingöl, Ferhat; Gökçen Akkurt, Gülden; Bingöl, Ferhat; Gökçen Akkurt, Gülden; 03.06. Department of Energy Systems Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyWind energy is still developing industry and people who work in this industry working hard to accomplish the difficulties. Problems are not arise only by nature of wind but technological developments, methods and even market pressure itself. Wind turbine theoretical power curves are given only for certain conditions and one can easily say that those conditions are not met in real sites. This difference generates a uncertainty in AEP calculations thus financial models become less reliable. Shifting power curve by taking atmospheric effects into account will give more realistic power curve thus more accurate AEP and financial models. In this study, effects of atmospheric conditions and correction methods on NREL 5MW wind turbines power curve have been investigated and importance of corrected power curve has been discussed.Master Thesis Anti-Reflective and Optical Transparent Coatings for Thin Film Solar Cells and Glasses(Izmir Institute of Technology, 2020) Özyüzer, Lütfi; Özyüzer, Lütfi; Özyüzer, Lütfi; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyAntireflective coatings in some implementation necessary for the decreasing surface reflection, but in some applications also for increasing transmittance. Incident radiation on the surface of the optical material is divided into transmitted, reflected, scattered, and absorbed proportions, and the proportion of current energy that deployed among them is defined by RI (refraction indices). Solar panels made from crystalline or polycrystalline silicon, but another type of solar panel is a thin-film solar panel. Thin-film technology has several advantages, such as low material consumption, which leads to cost savings to production, the ability to absorb diffused solar radiation, a relatively high efficiency (up to 20%), long service life (efficiency decreases by 10-15% of the initial efficiency). For all types of photovoltaic devices, energy loss is an important issue. Single-layer and two-layer antireflection coatings with a low refractive index, coated and uncoated (SiO2) thin-film with the sol-gel method were prepared and compared in terms of performance and continuity. The photocatalytic performance of (SiO2) thin films in 1, 2, 3, 4, 5 and 24 hours was defined with methylene blue dye solution (20 mL) under UV source and was illuminated by it. The I-V characteristics curve of solar cells for small and large area was learned and increasing efficiency was observed. Adhesion tests in this study was applied by tape tests on substrates of glass. As a result, the field tests of small and large area glasses coated solar panels were realized, the low reflectance and high efficiency were obtained.Master Thesis Natural Ventilation Design for Historic Libraries With Cfd (computational Fluid Dynamics) Simulation(Izmir Institute of Technology, 2019) Gülhan, Özcan; Gökçen Akkurt, Gülden; Gökçen Akkurt, Gülden; Erek, Aytunç; 03.06. Department of Energy Systems Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyLibraries accumulate and protect written and printed works that make permanent knowledge and cultures have been accumulated throughout human history. Paper-based collections kept in libraries are the heritage of humanity. They are under risk of mechanical, biological and chemical degradation over the years caused by the fluctuations in temperature and relative humidity values and inability to control these values. The aim of the Thesis is to reduce degradation risks on paper-based collections in historic libraries by providing preventive conservation without damaging the structure of the building. The historic Necip Paşa Library which is home for 1147 manuscripts was chosen as a case study. In order to provide preventive conservation for manuscripts, firstly indoor microclimatic data were collected for one year and analyzed to observe the risks that may cause degradation types on manuscripts. Only chemical degradation risk was detected. Window controlled seven natural ventilation scenarios were developed to reduce the risk. Finally, ventilation scenarios were analyzed by Ansys Fluent 17.1. Computational Fluid Dynamics (CFD) modelling was used to observe the effect of natural ventilation scenarios on indoor relative humidity according to outdoor relative humidity and wind direction. Finally, k-? turbulence model was used in CFD analysis. Results shows that during the high chemical degradation risk period (May-October), outdoor air temperature and relative humidity are suitable only 7.53% of the total time which allows appropriate natural ventilation. As a conclusion, natural ventilation is not enough to decrease chemical degradation risk totally for the Library. Therefore, additional mechanical ventilation is required.