A year-round efficient air source heat pump with separate and distant heat extraction for non-decaying heating capacity during defrosting

Boilers consume fossil fuels for heating in winter, making them neither economical nor environmentally friendly. Although air source heat pumps (ASHPs) can efficiently heat in winter, their performance decreases during frosting, and traditional defrosting methods cannot maintain stable heating capacities. A previous study developed an ASHP system with a non-decaying heating capacity; however, it was unsuitable for systems with large capacities and could not achieve efficient cooling. Thus, this study develops a year-round efficient ASHP with separate and distant heat extraction that achieves efficient cooling and heating without decaying the heating capacity during defrosting. The heating and defrosting performances of the prototypes were tested in a real project, and the economic performance was calculated and compared with that of a traditional chiller and boiler system in a case-studied building. The conclusions are as follows: (1) the developed system could effectively defrost, and the system heating capacity did not decay during defrosting; (2) compared to a traditional chiller and boiler system, this system achieves efficient and economical heating and efficient cooling; and (3) when applied to a case-studied building in southern China, the developed system achieves a 43 %–60 % energy-saving rate compared to a chiller and boiler system under various winter conditions, with an overall rate of 51 % for the entire winter season and a static payback period as approximately 2.9 years.