Analysis of lower GWP and flammable alternative refrigerants

High global warming potential (GWP) refrigerants for refrigeration and heat pump systems or organic Rankine cycle systems are being phased out because of their impact on climate change, such as R134a, R410A and R404A. So it is urgent to find the refrigerants with excellent environmental protection performance. Firstly, nearly 40 alternative refrigerants, including pure refrigerants and mixed refrigerants, are classified according to their environmental and safety characteristics. Secondly, the performance parameters of some typical alternatives, such as refrigerating capacity, COP, safety and environmental protection, are comprehensively compared. It can be concluded that R513a and R466A have good comprehensive performance as alternative refrigerants of R134a and R410A respectively, while those alternatives to R404A have both advantages and disadvantages. The application and technical characteristics of R32, some typical HFOs, natural refrigerants and mixtures are summarized and analyzed. In addition, our group has carried out experimental and theoretical research on the flammability of low GWP and flammable refrigerants such as R1234yf, R161, R290, R600a and R1150, and found that hydrocarbons are more difficult to be inhibited than halogenated hydrocarbons. Finally, a new research idea on the risk of refrigerant explosion is put forward, which can cover the refrigerant leakage, combustion and risk aversion.