Master Degree / Yüksek Lisans Tezleri

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Access Right: Open AccessAuthor: search.filters.author.Gökçen Akkurt, Gülden

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Now showing 1 - 10 of 22
  • 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, Gülden
    Indoor 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 Utku
    Water 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
    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
    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, Gülden
    Libraries 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, Gülden
    Wind 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, Aytunç
    Libraries 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.
  • Master Thesis
    An Investigation of Transient Water Vapor Migration in Building External Walls
    (Izmir Institute of Technology, 2019) Turgut, Çiğdem; Başaran, Tahsin; Gökçen Akkurt, Gülden
    Building envelope design is very important for energy efficiency in the building due to control the mass and energy transfer between the internal and external environments. Additionally, this performance is also important for obtaining indoor air quality and comfort conditions in the built environment. The study aims to analyze the heat and moisture performance of the different building exterior wall types composed of the different structural elements and insulation materials. Two different analysis models were used for this study. The objective of the thesis is to predict the physical, chemical and biological problems in the building envelope that will arise due to condensation in the design stage. So, saving cost and time will be provided to consumers. In the scope of the thesis, the heat and moisture performance of 21 different wall sections that composed commonly used structural body elements (concrete, brick and aerated concrete) and insulation materials (XPS, EPS and MW) in different insulation situations (internal insulation, external insulation and non-insulated situation) were analyzed in steady and transient regimes. The interlayers with a risk of condensation were determined in the result of this study. The results of the two different analysis methods were evaluated and the differences of the methods were revealed. As a result of the study, it has been shown that the placement of the insulation material on the exterior side is more suitable for moisture.
  • Master Thesis
    Thermal Comfort Analysis of Historical Mosques, Case Study: the Ulu Mosque, Manisa, Turkey
    (Izmir Institute of Technology, 2019) Diler, Yusuf; Gökçen Akkurt, Gülden; Turhan, Cihan
    Mosques are sanctuary places for Muslims where they can communicate with each other and perform their religious activities. Mosques differ from other building types in terms of occupancy period during a day with their unique function and intermittent operating schedule. Historical mosques with cultural heritage value, contain lots of artworks and represent Turkish culture for centuries. These mosques are originally built and serve without heating, cooling and mechanical ventilation systems. In this thesis, a systematic approach on monitoring and evaluating the microclimate and thermal comfort of historical mosques has been developed. This approach consists of two phases: detailed data collection and developing a dynamic building energy model. As a case study, The Ulu Mosque was monitored between 2015 and 2018. Thermal comfort evaluation of the mosque during worship periods were conducted based on the method provided by EN ISO 7730 standard. A dynamic Building Energy Performance Software, is used to model the mosque, and the model was calibrated by hourly indoor temperature data. The calibrated model, which meets ASHRAE 14 requirements, is used to develop retrofitting proposals. Thirteen different scenarios were proposed to improve thermal comfort during worship periods. The results were then evaluated according to EN 16883 standard in terms of the conservation of cultural heritage. Electric radiator heating with intermittent operating schedules was obtained as the best options to protect cultural heritage, while decreasing dissatisfaction level from 45% to 10% in winter months. Additionally, comparing with continuous operating schedule, intermittent operation saves 46.9% energy.
  • Master Thesis
    Hybrid Energy Capacity of Turkey for Small and Micro Scale Energy Production
    (Izmir Institute of Technology, 2017) Yıldız, Mustafa; Bingöl, Ferhat; Gökçen Akkurt, Gülden
    Turkish state has opened a new possibility on investing small or micro scale energy production without license in 2014. This is a new step in Turkish energy market and two renewable energy sources are considered to be the main interest; wind and solar. Although there are studies covering both technology separately, currently there is no hybrid system assessment methodology and results for the country. This thesis aims to create a quantified hybrid energy capacity of Turkey. The study will include total energy capacity of a given location based on small scale wind and solar and furthermore would be able to suggest an optimum balance between these two sources to get the maximum production capacity out. The study does not cover areas that such investment cannot be done; environmental protected areas, historical places, city centers etc.
  • Master Thesis
    Adaptive Thermal Comfort Analysis of Historic Mosque: the Case Study of Salepçioğlu Mosque, Izmir, Turkey
    (Izmir Institute of Technology, 2016) Bughrara, Khaled S. M.; Durmuş Arsan, Zeynep; Gökçen Akkurt, Gülden
    Mosques differ from other types of buildings by having intermittent operation schedule. Due to five prayer times per day throughout the year, mosques are fully or partially, yet periodically, occupied. Historic mosques, possessing cultural heritage value, need to be evaluated in terms of thermal comfort. The adaptive thermal comfort method presented by ASHRAE 55 is recommended to be used to analyze thermal comfort conditions of unconditioned buildings. The aim of research is to analyze thermal comfort conditions of historic mosques throughout the year, and to conduct an adaptive comfort analysis. The selected Salepçioğlu Mosque was built in 1905 in Kemeraltı, İzmir, Turkey. The objective is to improve indoor thermal comfort levels by applicable interventions with specific attention to its heritage value. First, indoor and outdoor microclimate of Salepçioğlu Mosque was monitored from October 2014 to September 2015. The physical model of mosque was created via dynamic simulation modelling tool, DesignBuilder v4.2. The model was calibrated by comparing simulated and measured indoor air temperature within hourly error ranges defined by ASHRAE Guideline 14. Whole-year thermal comfort analysis was conducted on monthly basis by using adaptive thermal comfort model. The adaptive comfort analysis of monitoring campaign shows that the Mosque does not satisfy acceptable comfort levels. Different scenarios were applied to better comfort levels. The best improvement is obtained with underfloor heating by which discomfort hours drop into 1369 hours by 31.34%, while it was 3760 hours by 86.08% in the baseline model.