Effects of N2 and 1,1,1,3,3,3-Hexafluoropropane (C3H2F6) on Inhibition of Coal Flames

Abstract

Two gaseous fire-extinguishing agents, N2 and C3H2F6, were used to suppress open-flame coal combustion, and their inhibitory effects as well as the corresponding mechanisms were probed by simulations and confined-space experiments. The influence of N2 on the flame surface area linearly increased with increasing N2 concentration, while a sudden increase in reduction was observed from C3H2F6. In addition, C3H2F6 was capable of inducing well-pronounced flame flash-off and featured an extinguishing time smaller than that of N2, thus being a more efficient extinguishing agent. The above findings were rationalized by numerical simulations, which revealed that whereas N2 extinguished the flame mainly by dilution of reactive intermediates, C3H2F6 decomposed to produce F-containing species that competed with coal for OH, H, and O free radicals and thus cut off the free-radical chain reaction.