Experimental investigation on the dynamic thermal performance of the parallel solar-assisted air-source heat pump latent heat thermal energy storage system

In this study, a dual-source solar-heat pump latent heat thermal energy storage system for hot-water supply was proposed to take advantage of renewable energy sources. An experimental setup mainly consisting of a solar heat collector with a gross area of 2 m² and an air-source heat pump with a maximum capacity of 2 kW was established to evaluate the adaptability of the phase-change material to the solar-heat pump and the feasibility of the heating system. A comparative study was carried out to investigate the effects of the operation modes on the system thermal performance and explore optimal operating parameters. Compared to the single heating mode, the overall efficiency of the system was enhanced by about 57.5% under the combined heating mode due to the introduction of solar energy. The coefficient of performance of the heat pump significantly increased from 2.09 to 2.60 when the flow rate increased from 0.010 L/s to 0.038 L/s. However, an increase in the flow rate could not significantly improve the overall efficiency of the entire heating system due to the higher power consumption of the pump. The storage unit exhibits a great storage density of about 211.13 MJ/m³ with a volume saving rate of 21%.