Effect of gas disturbance on combustion characteristics of flammable refrigerants near LFLs.

Refrigerants with low global warming potential (GWP), will play an important role in the research of alternative refrigerants and the development of new refrigerants, but most of them are flammable. And the actual environment of the refrigeration system varies with different factors, especially gas disturbance. In this paper, the combustion characteristics of four refrigerants, i.e., isobutane (R600a), ethylene (R1150), propane (R290), and 2,3,3,3-Tetrafluoroprop-1-ene (R1234yf) under the conventional static and the gas disturbance were studied. Firstly, the flame characteristics and lower flammability limits (LFLs) of the refrigerants were investigated. Then the special combustion phenomena were observed and analyzed in the presence of the gas disturbance, and an improved method for better defining the LFLs of the flammable gases under the disturbance was proposed. Finally, the experimental results show that the LFLs of the three natural refrigerants under specific low disturbance are lower than that in normal conditions, but except for R1234yf. It was found that the specific disturbance may enhance the combustion intensity by comparing the burning time of visible flame under the two conditions. The results have guiding significance for the safe application of flammable refrigerants.