Application and Exploration of Carbon Dioxide R744 as Refrigerant and Secondary Refrigerant in Refrigerating Unit of Commercial Super

In this paper, the cascade refrigeration system and the load cooling system of the natural working medium are integrated as one unit system, which can meet the needs of different temperature zones of refrigerating in supermarkets. The concrete implementation scheme of the unit system with R717 as high temperature refrigerant, CO2 as low temperature refrigerant and carrier refrigerant was designed. According to the actual load of commercial super, the design and calculation of NH3 refrigerant system, CO2 refrigerant carrier system and CO2 cryogenic system were carried out. Through calculation and testing, the ideal refrigeration effect of the unit is obtained. Compared with the traditional unit, the energy saving is 20%, emission reduction (translated into CO2 emission) is 40%, and the operation cost is reduced by 20%.