Experimental and numerical investigation on the heating performance of a novel multi-functional heat pump system with solar-air composite heat source

Abstract Multi-functional heat pump system with the functions of air conditioning and producing domestic water can operate throughout the year, so its working condition is more complicated than ordinary heat pump. The integration of composite heat source with multi-functional heat pump can be an effective approach to improve the operational stability. Based on the concept of multi-energy complementarity, a solar-air composite source multi-functional heat pump (SA-CMHP) system is proposed to fulfill the energy demand in buildings. The experimental prototype is built to study the performance of SA-CMHP in space heating mode. The experimental results show that SA-CMHP achieves the optimal performance at the EXV opening degrees of (20, 20). Mathematical model of SA-CMHP is developed, and the impact of ambient temperature, solar irradiation and wind speed on heating performance is identified. It is revealed that the rise of outdoor ambient temperature is beneficial for the improvement of heat transfer performance of both evaporators. The evaporation capacity of solar collector increases as solar irradiation rises, while the variation of the evaporation capacity in outdoor air heat exchanger shows the opposite trend. With the wind speed rising from 1 m/s to 6 m/s, the COP rises from 2.11 to 2.40.