Frosting performances of the metal heat-transfer surface for the air-source heat pump in Harbin

The frost formation on the metal heat-transfer surface of the air-source heat pump system dramatically weakens the system heating capacity. In this study, a frost formation experimental system based on the metal heat-transfer surface was implemented in the severely cold region of China, Harbin. The frosting performances including frost layer thickness and mass as affected by the ambient temperature, metal-surface temperature, and relative humidity were compared and analyzed, and the Response Surface Method was applied to analyze the significance degrees of experimental parameters. The results reveal that when the ambient temperature gradually decreased from 4 °C to -10 °C, the frost layer thickness and mass on the copper surface decreased. When the metal-surface temperature gradually decreased from -10 °C to -25 °C, the thickness and mass of the frost layer on the copper surface gradually increased. When the relative humidity gradually rose from 50% to 90%, the thickness and mass of the frost layer on the copper surface increased. The significance rank of experimental parameters for the frost layer mass was the metal-surface temperature > humidity > ambient temperature.