Energy Systems Engineering / Enerji Sistemleri Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/4752
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Article Citation - WoS: 1Citation - Scopus: 1Energy and Exergy Analysis of a Geothermal Energy Sourced Hot-Air Drying System(Inderscience Enterprises, 2023) Helvacı, Hüseyin Utku; Keleş, Nazlı; Gökçen Akkurt, GüldenA geothermal energy-sourced drying system was tested for the thin-layer drying process of tomato slices at air temperatures of 40 degrees C, 50 degrees C and 60? and velocities of 0.5 m/s and 1.5 m/s to investigate system performance in terms of the first and second laws of thermodynamics. The energy and the exergy efficiency of the system were found to be 6.6% and 22.31%. The energy utilisation and energy utilisation ratio were calculated in the range of 1.271 kW-5.102 kW and 9.644%-39.56%, respectively. The exergy destruction, exergy efficiency and improvement potential of the drying chamber varied between 0.0198 kW-0.2621 kW, 59.74%-81.95% and 0.00486 kW-0.07396 kW, respectively.Article Citation - WoS: 1Citation - Scopus: 1Thermodynamic Re-Assessment of a Geothermal Binary Power Plant Operated in a Moderate-Temperature Geothermal Field(Inderscience, 2023) Özcan, Zeynep; Gökçen Akkurt, GüldenAn existing organic rankine cycle power plant which uses isobutane as working fluid is re-evaluated for different working fluids. The plant is first modelled by EES software; then the model is simulated for different working fluids obtaining heat transferred through the heat exchanger, net work output, energy and exergy efficiencies, and mass flowrate of the working fluid. Two parametric studies are conducted to evaluate the thermodynamic performance of the plant under a range of turbine inlet temperature (130°C–155°C) and geothermal resource temperature (152°C–161°C) for each working fluid. The study reveals that the highest cycle energy and exergy efficiencies are observed for R-152a at any geothermal resource temperature. R-152a resulted with 13.1% and 58.2% cycle energy and exergy efficiency, respectively at operation condition, whilst the lowest efficiency and net work output is calculated under n-butane presence.Article Citation - WoS: 31Citation - Scopus: 33Energy and Exergy Analysis of a Pv-T Integrated Ethanol Pem Electrolyzer(Pergamon-Elsevier Science Ltd, 2021) Çağlar, Başar; Araz, Mustafa; Özcan, Hüseyin Günhan; Çalışan, Atalay; Hepbaşlı, ArifA photovoltaic-thermal (PV-T) integrated ethanol proton exchange membrane electrolyzer (PEME) was proposed as a low-energy consuming energy storage option for renewable-sourced electricity as well as a way for simultaneous chemical production in this study. Energy and exergy analyses were applied to each component of the system (e.g., pumps, heat exchanger, PV-T, PEME, and separation unit (SPU)) and the whole system to assess the system performance. The mathematical modelling of the whole system along with its main components except for the SPU was done using the Engineering Equation Solver (EES) software package while the SPU was modelled through the ASPEN Plus. A detailed modelling of the PEME was also included. The effects of the PV-T and PEME parameters on energy and exergy efficiencies of the system were evaluated while the improvement potentials and scale up options were discussed. Energy and exergy efficiencies of the proposed system at the optimum operation of the PEME and under average climatic conditions in the city of Izmir, Turkey were determined to be 27.8% and 3.1%, respectively. Energy and exergy efficiencies of the system were mainly regulated by the PV-T and PEME, whose energy and exergy efficiencies were 40.6%, 56.6% and 13.8%, 14.1%, respectively. Effective PEME parameters for energy and exergy efficiencies of the system were membrane conductivity, membrane thickness, anode catalyst and the operation temperature of the PEME. By changing the PV-T and PEME parameters and by scale-up, energy and exergy efficiencies of the system could be improved.Book Part Citation - Scopus: 11Thermodynamic Performance Evaluation of a Geothermal Drying System(Springer Verlag, 2014) Helvacı, Hüseyin Utku; Gökçen Akkurt, GüldenRenewable energy sources such as geothermal energy can be used in drying processes as a heat source due to the high energy costs of fossil fuels. In this study, geothermal cabinet type dryer was constructed and situated in Balcova-Narlidere Geothermal Field, Turkey where the clean city water of district heating system is used as an energy source for the dryer. The dryer was tested on site for drying of olive leaves and energy and exergy analyses of the drying process conducted under two cases: Case 1. Exhaust air was rejected to the environment. Case 2. A portion of exhaust air was re-circulated. Energy Utilization Ratio (EUR) was determined as 7.96 for Case 1 and 50.36 for Case 2. The highest rate of exergy destruction occurred in the fan, followed by heat exchanger and the dryer, accounting for 0.2913, 0.05663 and 0.0115 kW, respectively. Exergetic efficiency of the drying chamber was calculated as 89.66 %. Re-circulating the exhaust air decreased the exergy value at the outlet of the dryer from 0.1013 to 0.08104 kW, indicating that re-using the air increases the performance of the dyer.