Browsing by Author "Basaran A."

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    Investigation of the effect of different refrigerants on performances of binary geothermal power plants
    (2013) Basaran A.; Ozgener L.
    The paper tries to review the argument of the use of working fluids for binary cycle power plants and has been dedicated to this specific argument with a more general perspective. Binary cycle that allows the production of electricity from geothermal energy sources is one of these systems. In this cycle, thermal energy obtained from geothermal sources is transferred to second working fluid. Therefore, selection of second working fluid plays a key role on the cycle performance. In this study, a sample geothermal binary power cycle was modeled and 12 refrigerants that are HFC, HC, and zoetrope refrigerant mixtures were selected as working fluid. Energy and exergy efficiencies of binary cycle were calculated for 12 refrigerants. Dry type fluids of investigated refrigerants R 236ea, R 600, R 600a, and R 227ea showed higher energy and exergy efficiencies, respectively. On the other hand, R 143a, R 415A, R 290, and R 413A that are wet fluids indicated lower energy and exergy efficiencies, respectively. © 2013 Elsevier Ltd. All rights reserved.
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    Prediction of heat and fluid flow in microchannel condensation
    (EDP Sciences, 2019) Basaran A.; Benim A.C.; Yurddas A.
    The condensing flow inside the microchannel has gained importance as the microchannel heat exchangers are widely used in the industry. In this study, a number of numerical simulations on condensing flow inside the microchannel were conducted to investigate heat transfer characteristic. Circularmicrochannel geometries with the various diameters were considered. The Volume of Fluid model was used to model twophase flow. The phase change at the saturation temperature was modeled by the Lee model.In the considered geometries, different from the conventional channels, surface tension forces can be importantcomparedto other forces. Therefore, surface tension was considered in the simulations. Constant wall heatflux and constant saturation temperature were applied as simulation conditions, similar to actual operating conditions. The predictions were validated by comparisons with the experimental results that exist in the literature. A satisfactory agreement of the present predictions with the experimental data was observed. © The Authors, published by EDP Sciences, 2019.
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    Numerical Simulation of the Condensation Flow of the Isobutane (R600a) inside Microchannel
    (Taylor and Francis Ltd., 2021) Basaran A.; Benim A.C.; Yurddas A.
    A numerical investigation of the condensing flow of isobutane inside microchannel has been performed. Impact of mass flux, hydraulic diameter, and vapor quality on the heat transfer rate and pressure drop is determined. To this purpose, steady-state numerical simulations of condensation flow of isobutane have been performed at mass fluxes ranging from 200 to 600 kg/m2s inside a single circular microchannel with varying diameter. Similar to the usual operation conditions, the simulations have been conducted for constant saturation temperature and constant wall heat flux as the thermal boundary condition. The proposed model has been based on the volume of fluid approach, which is an interface tracking method. The Lee model has been used to model the phase change mass transfer at the interface. A verification study has been performed by comparing the proposed model results with the experimental and visual data available in the literature. The currently available correlations are assessed by comparisons with the simulation results. Based on the presently validated simulations, a new correlation has been proposed for the heat transfer coefficient and pressure drop of isobutane condensing flow inside small-scale channels. This is a novel aspect of the present paper, since such a correlation does not yet exist. © 2021 Taylor & Francis Group, LLC.