Reliability verification of a solar–air source heat pump system with PCM energy storage in operating strategy transition

• Propose an innovative phase change material based hybrid solar–air heat pump system (PCM-SAHP).
• Design and test a prototype of PCM-SAHP for residential cooling and heating.
• PCM-SAHP achieves satisfactory capacity and energy efficiency, even during severely operating conditions.

In the recent decade, with solar energy assisted heat pump systems have increasingly developed. In the previous studies, a hybrid air source heat pump (ASHP) system was proposed, which coupled with latent heat thermal energy storage (LHTES) and solar thermal collector, for operating in various types of configurations. This paper describes the approach and principle for organizing the hybrid system in detail. Thereafter, a phase change material (PCM) based solar–air source heat pump (PCM-SAHP) prototype was set-up and implemented under variant testing conditions. Experimental results demonstrate that the PCM-SAHP system presented remarkable advantages on correcting the mismatch between supply and demand of thermal energy and electricity. Further, when the ambient temperature was higher than 38 °C, cooling COP of the hybrid system enhanced by 17%, compared with that of ASHP system under same surroundings. During the days that outdoor air temperature was below −10 °C, heating COP of the PCM-SAHP system rose by 65% comparing with that of ASHP system. In additional, switching operating strategies during system running will scarcely result in the violent or continuous fluctuations on the operating parameters. Therefore, the efficiency of the PCM-SAHP systems can be improved with capacity lapse avoiding, and exhaust controlling as well.