To investigate the impact of defrosting-water retention on the surface of heat exchangers of the air source heat pump (ASHP) performance during frosting–defrosting cycles, an experimental study has been conducted. Testing was carried out in a controlled-environment chamber with ASHP...

A study is presented on the characteristics of the air source heat pump (ASHP) under two kinds of typical mal-defrost phenomena. The definition of the “Mal-defrost phenomena” is put forward, and the possible origins of their occurrence are analyzed. It is concluded that the current defrost...

To quantify the performance drop of the air source heat pump (ASHP) system under a special kind of mal-defrost phenomenon appearing in moderate climate conditions, a field test was conducted for 8days at the initial stage of a heating season in Beijing, China. The mal-defrost was found with the...