Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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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 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 Optimization of Energy Consumption and Thermal Comfort in Historic Buildings: Case Study of İzmir National Library Building, Türkiye(01. Izmir Institute of Technology, 2023) Özsavaşcı, Umut; Durmuş Arsan, Zeynep; Gökçen Akkurt, GüldenThe 'library,' as a building type, is the visiting space of researchers and storage space of wisdom of past and present thinkers. Historic libraries host unique pieces of cultural heritage such as books, manuscripts, documents, maps, artifacts, paintings, sculptures, and frescos from the previous generations. The thesis aims to reduce energy consumption and improve occupants' comfort while paying attention to degradation risks of paper-based collections in the historic İzmir National Library Building, Türkiye. Thus, it examines building retrofit actions with different impact criteria and conducts the optimization tool to define the most optimal ones. First, three degradation risk assessment procedures were determined for the paper-based collections of the İzmir National Library Building. Within the scope of the thesis, the library building was monitored between 01.10.2016 - 01.10.2017. According to the results of the monitoring process, mechanical, chemical and biological degradation risk analyzes were carried out. The digital simulation model of İzmir National Library was prepared in DesignBuilder v. 7.0.0.102 software and calibrated monthly for a year via hourly air temperature data. Three retrofit optimization scenarios, i.e. neutral, low and high risk impact criteria, were defined by grouping different design variables such as glazing type, exterior door material, pitched roof floor construction, exterior wall construction, heating set point and cooling set point of HVAC system. The objective of optimization was reducing energy consumption and discomfort hours at the same time. The simulation results showed that all three retrofit actions reduced energy consumption and discomfort hours. Scenario 3 was the most successful among other scenarios, providing energy savings by 26.6% and reducing discomfort hours by 80.3%, according to the base case. Besides, there was no significant change in the degradation risk analyzes according to the base case.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, MousaEnergy 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 Experimental Investigation and Computational Fluid Dynamics (cfd) Analysis of Geothermal Sourced Hot Air Drying(Izmir Institute of Technology, 2022) Keleş, Nazlı; Gökçen Akkurt, Gülden; Helvacı, Hüseyin UtkuDrying 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) Birim, Necmiye Gülin; Gökçen Akkurt, Gülden; Turhan, CihanAir 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 Energy Performance Analysis and Materials Characterization of Aerogel Insulation Blankets(Izmir Institute of Technology, 2022) Alan, Selena; Gökçen Akkurt, Gülden; Akkurt, Sedatİzmir 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 The Effect of Restoration Interventions on the Indoor Climate of Historic Buildings: Case Study of Tire Necip Paşa Library, İzmir, Turkey(Izmir Institute of Technology, 2022) Çağırgan, Umut; Durmuş Arsan, Zeynep; Gökçen Akkurt, GüldenLibraries are collections of recorded information which can host cultural heritage values that must be protected against mechanical, chemical and biological degradation. To prevent degradations, libraries require stable indoor climates with minimal temperature and relative humidity fluctuations and low concentrations of indoor air pollutants. Aim of the thesis is to investigate if installing a HVAC system is effective in improving the indoor climate of a historic library as a long-term preventive conservation method on the preservation of paper-based collections. Tire Necip Paşa Library in İzmir was selected as the case building which underwent restoration and a HVAC system integration in 2015. Library’s indoor climate was investigated before 2015 which allowed the comparison of pre- and post-restoration periods. Within the scope of this thesis, library was monitored at five locations between 2019-2021. 2019-2020 monitoring results were compared to pre-restoration monitoring results in terms of degradation risks and ASHRAE Chapter 23 control classes. Pre- and post-restoration indoor climates satisfied A1 and AA control classes, respectively. While there were mechanical and chemical degradation risks before restoration, no risk was observed post-restoration. There was no biological degradation risk during either periods. Additionally air pollutants were sampled during summer and winter of 2020-2021 which showed high SO2 and NO2 concentrations. Lastly the BES model of library was prepared and calibrated to investigate if existing HVAC system will continue to provide a stable indoor climate on future. The results of 2050 and 2080 simulations showed that HVAC system will struggle to provide a stable indoor climate.Master Thesis Wind Turbine Power Curve Update Based on Atmospheric Conditions and Structural Fatigue(Izmir Institute of Technology, 2020) Demir, Erdem; Bingöl, Ferhat; Gökçen Akkurt, GüldenWind 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 Natural Ventilation Design for Historic Libraries With Cfd (computational Fluid Dynamics) Simulation(Izmir Institute of Technology, 2019) Gülhan, Özcan; Gökçen Akkurt, Gülden; Erek, AytunçLibraries 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.
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