Abstract: Although there are already products on the market using R290, there is room to improve its annual performance factor(APF). Optimizes the heat exchange system of a 1.5-horsepower R32 household wall mounted air conditioner using R290 refrigerant as substitute to improve its energy efficiency through simulation and experimentation. Firstly, the optimal refrigerant filling amount was tested. The results showed that the system had the best performance when the filling amount was 300 g, with APF of the system reaching 4.812, and the filling amount met the maximum filling amount requirements of the specifications. Secondly, through testing, it was found that when replacing R32 with R290 refrigerant, there were two aspects that need special attention due to different characteristics of the refrigerants: (1) R290 refrigerant had higher requirements for the distribution effect of the distributor, and the problem of uneven distribution in the heat exchanger could be greatly improved by optimizing the distributors of internal and external unit; (2) R290 refrigerant was sensitive to pressure drop. By eliminating the subcooling section and replacing the connecting pipe, the system pressure drop could be effectively reduced. The APF of the prototype increased by 5.84% after optimization, reaching first level of the energy efficiency of national standard.

Key words: R290, Room air conditioner, System optimization, Energy efficiency