In this study

the leakage diffusion and concentration distribution characteristics of R32 refrigerants from a wall-mounted split air-conditioner indoor unit are analyzed by combining experiments and simulations under different leak locations

refrigerant leak rates

and operating conditions. Safety is compared and evaluated based on whether the R32 mass fraction reaches the R32 refrigerant detector alarm concentration (4% LFL)

the positions of the responsive detectors

and the lower flammability limit (LFL) area. The results show that the response time of the detectors inside the indoor unit is approximately 40 s and 50% faster than that located in the room. The experimental and numerical results show a high consistency. The diffusion law of R32 is different at different leak locations. The leak rate of R32 slightly influences the concentration distribution in the indoor unit. The area where the 4% LFL is reached when the air conditioning is ventilated is four times smaller than when the air conditioning is turned off. The best position to install the R32 refrigerant detector is the lower area between the electrical box and the front heat exchanger. When R32 leaks at the fin of the heat exchanger

the R32 refrigerant detector fails to respond

and the refrigerant continues to leak into the room

posing a safety hazard. The LFL volume is approximately 3×10-6 m3. The LFL region is a small area around the R32 leak port

and its safety risk is low.