Abstract: In order to explore the optimization direction of using R290 as a substitute for R32 in residential split air conditioners, conducted comparative analysis, including thermal property analysis, thermodynamic cycle calculation, and testing analysis of the two refrigerants on the same platform. The results of the system cycle calculations showed that the theoretical Carnot cycle performance of R290 is superior to R32. The results of the whole machine testing show that the rated refrigeration energy efficiency ratio of R290 decreased by 16.8%, and the rated heating energy efficiency ratio decreased by 5.6%. The main reason for the decrease in the overall efficiency of the R290 system is the poor stability of the saturation temperature of R290 with pressure fluctuations. Therefore, reducing the pressure loss on the low-pressure side becomes the key direction to improve the efficiency of the R290 system.

Key words: R290, Flammable refrigerant, Residential air conditioner