Experimental study of latent heat storage integration in a heat pump refrigeration circuit
Heat pumps (HP) are an efficient way to reduce the carbon impact of the building sector, which represented about 34% of energy-related emissions in Europe in 2022. Air-source heat pumps (ASHP) represent the majority of HPs installed worldwide; however, their performance deteriorates significantly at low ambient temperatures. Raising the evaporation temperature should significantly improve the seasonal performance of an ASHP. In this study, an ASHP integrating a latent thermal storage that can replace the evaporator when outdoor conditions are unfavorable is studied. Energy is stored in the thermal storage by means of an additional heat exchanger that performs direct heat exchanges with the HP refrigerant. Warmest outdoor temperatures are used to charge the storage unit without impacting the system performance. A suitable Phase Change Material (PCM) has been selected based on its thermal features and its compatibility with the system and a prototype has been built to study the feasibility of such a system. The latent storage was able to efficiently store and release about 0.8 ????????h of thermal energy and raise the refrigerant evaporation temperature. An energy saving of 10% was observed when comparing the system in HP mode and in storage mode.