Abstract: Under the background of the dual-carbon strategy, both international and domestic environmental policies and regulations are gradually reducing the quotas of fluorinated refrigerants. Therefore, the research on environmentally friendly refrigerants as substitutes is urgent. Water, as a pure natural working fluid (R718), can achieve nearly zero carbon emissions throughout the entire life cycle of refrigerants. It is an ideal refrigerant from the perspectives of environmental protection and safety, and it also has good refrigeration performance. According to reports, the energy efficiency level of R718 compression cycle refrigeration systems is comparable to that of refrigerants such as R134a and R290. Developed countries such as Denmark, Germany, Japan, and the United States are at the forefront of research and promotion of water vapor compression cycle refrigeration technology. However, China is still in the theoretical research stage, and there have been no reports of practical applications of water vapor compression cycle refrigeration systems in China. With the vigorous development of China's HVAC industry and the continuous restriction of HFC refrigerants, the environmentally friendly, safe, and good-performing R718 refrigerant will have broad development prospects.

Key words: Refrigerant, R718, COP, Water vapor compression cycle refrigeration