Temperature-rise matching and optimization of a recompression high-temperature steam heat pump system with staged subcooling

This study investigates a high-temperature heat pump (HTHP) system that combines steam generation and recompression process. The innovation of this work lies in proposing a staged subcooling configuration and achieving temperature-rise matching and optimization based on system operating characteristics studied. Key findings include: (1) The proposed staged subcooling configuration leads to clear performance gains, particularly under large temperature-rise heating conditions; (2) The integration of recompression significantly boosts system performance, especially at higher saturated steam temperature demands. As the recompression ratio increases, the system COPh,t follows a characteristic three-stage trend: “rapid rise, slow plateau, and gradual decline”; (3) A selection criterion for “80% effective recompression ratio” is established to balance system performance, stability, and cost. Under the studied conditions, recompression leads to a maximum effective improvement in COPh,t of 18.4%; (4) Performance optimization and operational guidance for the system are achieved by optimizing the intermediate pressure and selecting an effective recompression ratio, which can be uniformly converted into an internal temperature-rise matching relationship. This study not only provides innovative concepts and a theoretical foundation for the development of high-performance HTHP steam systems, but also offers a unified parameter optimization strategy applicable to related systems.