Experimental research on the explosion characteristics in the indoor and outdoor units of a split air conditioner using the R290 refrigerant

• The explosion overpressure within the indoor unit R290 was measured.
• The explosion characteristic near the fan was studied.
• The explosion overpressure within compressor sub-compartment was measured.

Currently, the most common refrigerants used in household split air conditioners are R22 and R410A. Due to environmental concerns, benign options such as R290 (propane) are under consideration as an alternative. However, R290 is flammable, which poses additional fire and explosion risks. The ignition source and location of the leak that may appear within the indoor and outdoor units were analysed. A series of experiments were carried out to better understand the ignition hazard. The explosion characteristics associated with the indoor and outdoor units were studied whereby the overpressure arising from ignition of R290 was measured at different locations. According to the internal volume of indoor and outdoor units, the amount of R290 that should be deposited inside the indoor and the outdoor units is 7 g and 16 g respectively, to form a stoichiometric concentration. The explosion overpressure in the indoor and outdoor units is sufficiently low so as to not damage the air conditioner system. However, if R290 is ignited during the leak, the indoor or outdoor unit will be burned.