Abstract: Heat pump air conditioners have a high popularity rate due to their ability to cool in summer and heat in winter, which puts forward higher requirements for the comfort of air conditioning. Frosting under rated heating conditions is a common occurrence in most air conditioners, and frequent frosting and defrosting under such conditions can easily cause customer complaints. By analyzing the frost formation mechanism of outdoor heat exchangers and combining experimental research, the problem of frost formation in outdoor heat exchangers under rated heating conditions is solved by adjusting the refrigerant flow rate of the system and the heat exchange air volume of the internal and external units.

Key words: Heating, Frosting, Defrost