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    Assessment of wind energy potential: a case study
    (Bellwether Publishing, Ltd., 2021) Düzcan, Abdullah; Kara, Yusuf Ali
    Utilization and investments of wind energy have been speedily rising in the world due to harmful side of the fossil fuels. Assessment of wind energy potential analysis is a must before making investment decision of wind farm. Due to high capacity factor of Aegean Sea, Gökçeada location is chosen for wind energy potential analysis. One year hourly measured wind velocity and direction data supplied by Turkish State Meteorological Service (TSMS) is used to assess the wind potential in the terrain. Two different approaches are used for the assessment, the former employs power-law method for calculating wind velocity field while the latter employs Windsim software based on Computational Fluid Dynamics (CFD) method. After calculating wind velocity field, Weibull method is used for energy analysis in both approaches. Results from each approach are compared. The roughness is attained at only two points that are measurement site and turbine site in power-law method while it is taken into account for the whole domain in CFD method. Besides, unlike CFD method, wind direction is not considered in power-law method. The velocity profile is calculated at the height of 60 m and considered the same everywhere depend on the roughness in power-law method. On the other hand, Windsim calculates velocity profile over the terrain in consideration by solving Reynolds-averaged Navier-Stokes (RANS) equations. In this assessment, seven Vestas V90 2 MW wind turbines are employed. According to the results of power-law method and CFD method, the capacity factor is calculated as 31.67 and 49.5%, respectively. Windsim results indicate that annual energy production (AEP) is 60.2 GWh/y regarding wake loss, and the shape factor ranges from 1.57 to 1.64 whereas scale factor ranges from 9.49 to 10.77 m/s for the locations of turbines. It is strongly advised to build a wind farm in Gökçeada location according to the results from the analysis.
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    Diurnal performance analysis of phase change material walls
    (Pergamon-Elsevier Science Ltd, 2016) Kara, Yusuf Ali
    A research study was conducted to investigate the thermal performance of phase change material (PCM) walls. The south-facing external wall of a test room was constructed using PCM walls composed of brick walls, plasterboards containing PCMs, and novel triple glass. The thermal performance of the PCM walls was experimentally determined on a daily basis. The ratio of the solar energy gain provided by the PCM walls to the heat load of the test room on a daily basis varied from 12% to 25%; daily overall efficiency of the coupled novel triple glass and PCM walls varied from 17% to 20%; and solar transmittance of the novel triple glass varied from 45% to 55% during the heating period. (C) 2016 Elsevier Ltd. All rights reserved.
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    ENERGY AND ENVIRONMENTAL EVALUATION OF A PCM WALL COVERED WITH NOVEL TRIPLE GLASS
    (2018) Seyhan, Aslıhan Kurnuç; Kara, Yusuf Ali
    Research was conducted to investigate the performance of phase change material (PCM) walls for solar space heating. The PCM walls were consisted of brick walls, plasterboards containing PCMs and novel triple glazing units. South façade of a test room was constructed using the PCM walls for heating the test room with solar thermal energy. The overall efficiency of the PCM walls was experimentally determined on a monthly basis. In addition to experimental analysis, a theoretical energy analysis of the PCM walls based on 10-year mean meteorological data was performed to provide a more general conclusion about the performances of the PCM walls. Besides, reduction in CO2 from the test room owing to PCM wall was also calculated. Theoretical analysis results showed that, the reduction of CO2 emission on a monthly basis varied from 57 to 7% during the heating period. Heating period is from October through May. Reduction of CO2 emission was 16% on an annual basis.
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    Exergoeconomic and exergoenvironmental analysis of a coal-fired thermal power plant
    (Springer Science and Business Media Deutschland GmbH, 2021) Düzcan, Abdullah; Kara, Yusuf Ali
    When evaluating a thermal system, exergy analysis is performed in addition to energy analysis to determine the location and quantity of losses in the system. In this study, energy, exergy, exergoeconomic and exergoenvironmental analyses of Orhaneli thermal power plant located in Bursa are carried out. In exergy analysis, physical and chemical exergies are taken into consideration and potential and kinetic exergies are neglected. Exergoeconomic analysis is conducted by using specific exergy costing (SPECO) method and cost values corresponding to each exergy flows are calculated. According to exergoeconomic analysis, unit exergy cost and exergy cost of steam sent to high-pressure turbine are calculated as 17.94 $/GJ and 22,854 $/h, respectively. The highest exergoeconomic factor is measured in pump (P2) and followed by P3. For the life cycle assessment (LCA) analysis, eco-indicator 99 impact assessment method is selected. LCA results are transferred to exergy flows and then exergoenvironmental analysis is performed. Environmental impact per exergy unit and exergetic environmental impact rate of the steam sent to high-pressure turbine are calculated as 14,680 mPts/GJ and 18,700 Pts/h, respectively. The highest exergoenvironmental factor is measured in pump (P2) and followed by P3.
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    Investigation of the usage potential of the evacuated tube and the flat plate collectors to assist an absorption chiller
    (Elsevier Ltd, 2021) Düzcan, Ahmed; Kara, Yusuf Ali
    In this study, the usage potential of the evacuated tube collectors (ETCs) and the flat plate collectors (FPCs) for assisting an absorption chiller (AC) are comparatively investigated by using TRNSYS software. ETC and FPC are examined under different load conditions and scenarios to see if the collectors satisfy the required source temperature for an absorption chiller system (ACS) with LiBr – H2O pair. Daily and seasonal analyses are carried out. Daily analyses consist of three scenarios: both the auxiliary heater and the load are turned off in the first scenario while only the load is turned on in the second; both the auxiliary heater and the load are turned on in the third scenario that is also performed for summer season as a fourth scenario. The working fluid in all scenarios is a heat transfer fluid (HTF). In the third scenario at 250 kg/h load, the maximum collector outlet temperature is 113 °C and 99 °C, the daily solar fraction (SF) is 83% and 57%, the temperature to load is 106 °C and 86 °C for ETC and FPC, respectively. In the seasonal analysis, the seasonal SF is 81% and 20.19% at 250 kg/h load for ETC and FPC, respectively. Higher temperature and SF are obtained when HTF is used instead of water. It has been observed that the required source temperature for ACS can be provided with ETC.