Proposal and performance analysis of a novel solar-assisted resorption-subcooled compression hybrid heat pump system for space heating in cold climate condition

Abstract

Absorption-resorption heat pumps (ARHPs) can efficiently utilize low-temperature solar heat for winter space heating, but are restricted by the relatively weak low ambient temperature adaptability. By combining the different strengthens of vapor compression heat pump (VCHP) and absorption-resorption heat pump (ARHP), a novel solar-assisted resorption-subcooled compression hybrid heat pump system with higher heating capacity under cold climate condition for space heating is proposed. Thermodynamic models for the hybrid system involving two subsystems are developed for performance evaluation under different operation conditions. Feasible high pressure/low pressure (PH/PL) and evaporation temperature/condensation temperature (Te/Ta) ranges for the hybrid system are revealed for component design. Based on that, performance evaluation indices like total coefficient of performance (COPtot), primary energy ratio (PER), primary energy saving ratio (PESR), coefficient from solar irradiation to heating capacity (SCOP) are investigated in terms of different PH/PL and Te/Ta values. The results showed that for the base-case, the above indices are 2.41, 1.66, 0.35 and 1.21, respectively. In addition, heat source temperature demand, heating capacity and ambient air temperature need of the hybrid system are compared with those of the conventional absorption heat pump (AHP), single ARHP and single VCHP under the same operation conditions. The results show that the hybrid system can extend the operation heat source temperature to above 72 °C, highlighting the possibility of integrating with common non-tracking solar collectors, and can extend the feasible ambient air temperature to above −20 °C. Moreover, by recovering the sub-cooling heat of VCHP subsystem for ARHP subsystem operation, the hybrid system can lift the heating capacity by over 50% based on the equivalent VCHP system.