Effects of N2and 1,1,1,3,3,3-Hexafluoropropane (C3H2F6) on Inhibition of Coal Flames

Two gaseous fire-extinguishing agents, N(2)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 N(2)on the flame surface area linearly increased with increasing N(2)concentration, while a sudden increase in reduction was observed from C3H2F6. In addition, C(3)H(2)F(6)was capable of inducing well-pronounced flame flash-off and featured an extinguishing time smaller than that of N-2, thus being a more efficient extinguishing agent. The above findings were rationalized by numerical simulations, which revealed that whereas N(2)extinguished the flame mainly by dilution of reactive intermediates, C(3)H(2)F(6)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.