Influence of refrigerant charge volume on the flammability risk of an R32 rotary compressor

Abstract

The use of R32 as an ideal alternative refrigerant has been widely considered, but its slight flammability cannot be ignored. Air intrusion into the compressor and diluting the R32 to a flammable concentration range will bring flammability risk. This article studies the influence of different refrigerant charge quantities on the flammability risk of R32 in a rotor compressor under certain air intrusion conditions. The exhaust pressure, temperature distribution, R32 flammable concentration area, and flammable volume time inside the compressor were studied by experiments and simulations. The results indicate that the R32 high-risk flammable area is near the compressor motor and exhaust port. Flammability risk keeps rising as air intrusion increases and rises substantially when the amount of refrigerant is insufficient. Special compressors for which the motors and exhaust ports can withstand high temperatures and pressure should be developed for the R32. The minimum allowable R32 charging standard should be calculated to ensure that the refrigerant concentration in the compressor is higher than the flammable upper limit when a certain amount of air intrudes. The results provide the technical basis for the formulation of standards for the safe use of R32 rotor compressors, to obtain the best application potential of the R32.