Comparison of the environmental effects and thermodynamic performances of dry and isentropic fluids in a geothermal heat sourced Organic Rankine Cycle

Organic Rankine Cycle (ORC) is an electricity generation system in which organic fluid is used instead of water in the low temperature range. ORC is used in power plants to use waste heat to generate electricity. In this study, thermophysical, environmental and thermodynamic performance comparisons of the ORC model were made using dry and isentropic fluids. Within the scope of geothermal applications, the heat source temperature was determined as 110 °C. The effect of changing the evaporation temperature between 65-100 °C on system performance was determined. As performance parameters, pump work, turbine work, input heat, irreversibility values, thermal efficiency and exergy efficiency have been determined for ORC. Thermodynamic analysis was performed using Engineering Equation Solver (EES). As a result of this study, it was observed that the highest values in terms of turbine work and thermal efficiency with R601 fluid were 54.72 kJ/kg and 11.34%, respectively, and 32.84 kJ/kg and 11.91% with R141b fluid, respectively. A fluid that performs best from dry and isentropic fluids has been proposed for ORC.