Volume 66

Thermodynamic Analysis of an Increasing-Pressure Endothermic Power Cycle: Comparison with ORC Hao Yu, Xiaoguang Wang, Di Deng, Xinli Lu

Abstract

Geothermal energy, as an abundant renewable resource, holds significant potential to serve as a reliable baseload power source in the future through advanced power generation technologies. The Organic Rankine Cycle (ORC) and ORC-based integrated systems, being relatively mature, have been widely adopted in geothermal power generation applications. In this study, a novel cycle (IPEPC) integrating combined heat and power generation is proposed, featuring an increasing-pressure endothermic process (IPEP) within the downhole heat exchanger (DHE) and utilizing refrigerant as the working fluid. The net power output and heat supply rate of the IPEPC system were evaluated by varying key operational parameters—namely injection pressure and mass flow rate—to identify optimal operating conditions. Compared with the conventional ORC, the IPEPC design achieves a more favorable thermal match between the working fluid and the geofluid temperature profile in the DHE. Thermodynamic performance of the IPEPC was systematically compared with that of the ORC across a geofluid temperature range of 100°C to 180°C. Results indicate that the IPEPC yields higher net power output than the ORC at lower heat source temperatures, particularly below 160°C.

Keywords combined heat and power generation, increasing-pressure endothermic process cycle, geothermal energy utilization