Study on the inhibition of hydrogen explosion pressure and flame propagation by trifluoroiodomethane

A 20L spherical device and a schlieren system were used to study the suppression effect of CF3I on the hydrogen explosion pressure and flame characteristics. The results show that CF3I can promote and inhibit the pressure parameters of hydrogen under lean fuel, but only inhibit the pressure parameters of hydrogen under equivalence ratios and rich fuel. Such as, phi = 0.6, adding 10 % CF3I, the maximum explosion pressure increased by 8.8 %. phi = 1, adding 5 % CF3I, the maximum explosion pressure decreased by 25 %. Different from the explosion pressure, the laminar burning velocity of hydrogen with different equivalence ratio decreases gradually with the increase of CF3I concentration. Numerical simulation was used to reveal the mechanism of CF3I inhibiting hydrogen. The results show that the concentration of active free radicals(H, O, OH) decreases with the increase of trifluoroiodomethane concentration. Further analysis on the rate of production and sensitivity of H free radicals found that R822 and R839 are the main generation reactions of H free radicals in the fluorine- and iodinecontaining elemental reactions, and R1397, R1396, R1391 and R859 are the main consumption of H free radicals reaction. The elementary reaction with the greatest inhibitory effect on H free radicals is R1391, and the elementary reaction with the greatest promoting effect is R850.