Abstract: Supermarket freezing cabinet have been rapidly developed due to the advantages of frost-free inside the box, large available space, and clean sanitation. However, the development is limited by the large power consumption of defrosting on the evaporator surface. Defrosting, especially in winter, is a very important topic for supermarket freezing cabinet. The application of hot gas bypass defrosting method reduces the power consumption of traditional electric heater defrosting, but there are also problems such as low suction temperature of compressor and long defrosting time in low temperature environment. In order to solve the above defrosting problems, the original hot gas bypass defrosting pipeline of air-cooled frost-free vertical freezing display cabinet in supermarket is reformed, and a new heat storage defrosting system is proposed. The heat exchanger with phase change heat storage is added to store the condensing heat during the operation of the system, and the heat is released in the process of hot gas bypass defrost to improve the suction temperature of the compressor. By testing the defrost performance of the modified system and the original system in different ambient temperatures, the following conclusions are drawn: in winter temperature, the defrost time of the modified system is shortened to 5% of the original system, and the defrost power consumption is reduced to 5.6% of the original system, which can solve the problem of low defrost efficiency of the original system in winter.

Key words: Supermarket freezing cabinet, Hot-gas bypass defrosting, Storage of condensing heat