Comparison of Thermodynamic Performance of Geothermal Organic Rankine Cycle with Two Different Working Fluids /

Abstract

The organic Rankine Cycle is a potential power-generating technology that can be used to transform low and medium heat sources into electricity. As compared to conventional Rankine Cycles, ORC operate at low operating pressures and temperatures. Organic fluids or refrigerants have low critical temperatures as compared to water which operates at higher temperatures as compared to organic fluids. Organic fluids can be utilized as working fluids in ORC applications as a substitute for water in the conventional Rankine Cycle. This research provides a thorough simulation of Organic Rankine Cycle processes for the conversion of heat energy from geothermal resources. The selection of the working fluids is vital since the performance of ORC systems is dependent on the working fluids. Power generated and thermal efficiency by a baseline ORC, recuperative ORC, and ORC with pre-heater are calculated with refrigerants R113 and R245fa at different evaporation temperatures and condenser temperatures. The comparison of baseline ORC, recuperative ORC, and ORC with pre-heater has been conducted. Evaporation temperatures have been optimized to acquire the highest power output at evaporator PPTDs of 5-15 °C and geothermal source temperatures of 150 °C, 168 °C, and 180 °C. Work output the efficiency of the cycle has been enhanced by the deployment of an internal heat exchanger. Cycle-Tempo is a modern graphical tool, which is used for optimization and thermodynamic analysis of the systems to create electricity, heat, and refrigeration. The temperature of the condenser has varied from 30 °C to 50 °C. The maximum power obtained is 2942.38 kW by working fluid R113 with recuperative ORC at the source temperature of 180 °C. According to the results, the recuperative ORC is the best performing configuration among the three configurations. The working fluid R113 shows maximum thermal efficiency of 14.84% with recuperative ORC.