Effect of halogenated flame inhibitors on C 1−C 2 organic flames

Abstract

The influence of CF 3 Br, CF 3 I, CF 4 , CHF 3 , C 2 F 6 , and C 2 HF 5 on laminar flame propagation in mixtures of CH 4 , CH 3 OH, C 2 H 6 , and C 2 H 4 with air has been determined by numerical simulations. Comparisons are made with experimental results and earlier calculations. Flame velocities as a function of inhibitor concentration and equivalence ratio have been determined. For all the organic fuels, the ranking of inhibitive efficiency is CF 3 Br, CF 3 I>C 2 F 6 >C 2 HF 5 >CHF 3 >CF 4 . The bromine and iodine compounds are clearly the most efficient flame suppressants. They are of equal effectiveness except in methanol, where CF 3 I is superior. The retardants are more effective for rich mixtures than for lean. With 1% inhibitor concentration, the decrease in burning velocity is most pronounced for unsaturated fuels. The general ordering is consistent with calculational results on flame thickness and radical concentrations. Reaction pathway analysis demonstrates the importance of the regeneration of reactive scavengers. Relative contributions from physical and chemical effects are estimated.