Performance and Evaluation of Heat Pump Systems Based on Waste Heat Utilization in Compressed Air Energy Storage

To mitigate compression heat loss during the operation of compressed air energy storage(CAES) power stations, this study proposed a design that coupled a CAES system with a heat pump system for high-temperature steam production. Focusing on waste heat utilization in a 100 MW CAES system, a tiered compression heat utilization strategy was adopted: part of the compression heat serves as a reheating source for the energy storage system’s expansion stage, while the remainder acts as a low-grade heat source for the heat pump steam generation system. This approach effectively enhances the comprehensive energy utilization efficiency of the system. Research findings demonstrated that the novel waste heat utilization system integrating a modified CAES system with a heat pump can convert 11.64 MW of secondary low-grade compressed heat into high-temperature steam. Under specific feedwater parameters(eg.,flow rate, pressure, and temperature), the system generated steam with matched operating conditions, while the heat pump subsystem achieves a Coefficient of Performance(COP) of 1.55. Analysis of variable operating conditions revealed that when the heat load of the flash-high/low-temperature regenerators remained constant, both the steam flow rate and flash rate increased with rising feedwater temperature and decreased with increasing feedwater flow rate. Furthermore, higher the feedwater flow rates combined with the lower feedwater temperature yield higher the steam temperature, peaking at 314.02 °C under optimal operating parameters; Environmental analysis indicated that the system produced substantial high-temperature steam during annual operation, achieving significant reductions in multiple pollutants emissions compared to coal-fired industrial boilers and thus providing a valuable technical reference for relevant fields.