With good thermal performance and environmental characteristics

R32 is a candidate for replacement of R22

but it is not adopted because of its slight flammability. This paper

in the view of indoor security

analyzes the leakage variation and the effect of supply air velocity and angle on the concentration distribution when the refrigerant leaks from the indoor unit with the air conditioner operating. The experimental results show that the refrigerant leakage rate decreases with time when the air-conditioning system works. The refrigerant leakage can be classified into two stages

fast leak and slow leak. Indoor environment security is evaluated and the results show that the combustible zone only appears near the leakage hole and its residence time is very short. Thus the risk level of using R32 as the refrigerant of air conditioner is low with the air conditioner operating.