Thermodynamic model-based specification of optimal geothermal power generation system for high-temperature liquid-dominated systems using flash and flash-binary cycles

The utilization of high-temperature geothermal fluid for power generation requires the most suitable generation system to maximize the output with the highest efficiency. Single-flash, double-flash, and flash-binary cycles are the most representative systems for a reservoir with high-temperature geofluids. This study aims to develop a thermodynamic model-based method for selecting the optimal power generation system using criteria of power output and energy and exergy efficiencies. For this purpose, a thermodynamic model of the power generation system was constructed to calculate these values for high-temperature geofluids at 230-350 degrees C under steadystate conditions. The critical thermodynamic parameters that control these criteria include the separator pressure for the single and double flashers, working fluid, turbine inlet pressure, brine outlet temperature, and pinch point temperature, all of which are incorporated into the calculation. The results show that the flash-binary cycle generates the highest power; 21% higher than that of a single-flash cycle at the 5 degrees C pinch point, and 7% higher than a double-flash cycle. In addition to this merit, a cautious temperature of 120 degrees C is recommended for the cold reinjection fluid of a flash-binary cycle, which is considerably lower than that for the single-and double-flash cycles (164 degrees C).