Abstract: At present, air-cooled refrigerators have a relatively large market share, but their refrigeration evaporators rely on electric heating for defrosting, which has problems such as high power consumption, high freezing temperature rise, and poor preservation. Therefore, new heat pump defrosting systems for single system and dual system frost free refrigerators were proposed separately. The heat pump converts less electricity into increased defrosting heat. Through system simulation theory analysis and whole machine experimental research, it was finally verified through experiments that the heat pump defrosting scheme has significant advantages over electric heating defrosting. Among them, the energy consumption of refrigerator heat pump defrosting can be improved by more than 80%, and the temperature rise in the freezing room can be reduced by more than 50%. The heat pump defrosting solution provides a new technological route for the energy efficiency upgrade of future refrigerators and the research and development of ultra efficient refrigerators.

Key words: Frost-free fridge, Heat pump defrosting, Defrosting energy consumption, Freezing temperature rise