Air-source heat pump assisted absorption heat storage for discharging under low ambient temperature

Absorption heat storage can realize high energy storage density (ESD) and efficiency. However, its performance is significantly constrained by the icing risk and reduced ESD under low ambient temperature. To mitigate these challenges, this study proposes a coupled system of air-source vapor compression heat pump assisted absorption heat storage. When discharging under low ambient temperature, the air-source vapor compression heat pump consumes small amount of electricity and lifts the evaporation temperature of absorption heat storage, thus avoiding the icing risk and ensuring efficient operation. Theoretical and experimental analyses for the proposed system were conducted for deeper insights. The theoretical analysis demonstrates that, with the assistance of air-source vapor compression heat pump, the absorption heat storage can provide high-temperature heat output of 65 °C under cold ambient condition. By optimized the coupled temperature during discharging, absorption heat storage and heat pump can work at high ESD of 320.5 kWh/m3 and high coefficient of performance (COP) of 4.18, respectively. Besides, the electrical COP of the coupled system is no less than 3.5 under the ambient temperature of −15 °C. Experimental results validate that the coupled system can sustain a high ESD of approximately 200 kWh/m3, with an output temperature of 65 °C under cold ambient condition. This study offers a promising solution to expand the application of absorption heat storage by integrating the heat storage and heat pump technologies.