Abstract: With the implementation of the Kigali Amendment, HFCs gas fire extinguishing agents with high GWP, represented by HFC-227ea, will be restricted from use. Therefore, the research on alternatives to such fire extinguishing agents is of practical significance. The green and environmentally friendly refrigerant HFO-1234yf, as a fluorine-containing olefin compound, also belongs to the screening range of alternative fire extinguishing agents. In this paper, the critical extinguishing volume fraction of HFO-1234yf to extinguish the n-heptane flame is 11.4% by using a cup burner. To improve its fire extinguishing efficiency, KHCO3, NaHCO3 and ABC dry powder are used to carry out the mixed fire extinguishing research of gas and solid, respectively. The results show that there are different synergies between HFO-1234yf gas and the three powders, and the synergies are the best when the powder mass concentration is 40.2, 55.1 g/m3 and 67.4 g/m3, and the corresponding peak synergies are 0.884 8, 0.892 6 and 0.931 0, respectively. The combination of suitable dry powder extinguishing agent and HFO-1234yf can reduce the extinguishing concentration of HFO-1234yf and improve its extinguishing efficiency.

Key words: HFO-1234yf, cup burner, composite extinguishing agent, dry powder extinguishing agent, coordinated fire fighting