Fire Safety Science Digital Archive

Effect of flame temperature on the efficiency of catalytic inhibition cycles by CF3Br in methane air counter flow diffusion flames are numerically investigated with detailed chemistry and transport. Computational results are compared with the previous finding of one-dimensional freely propagating flames, in which the efficiency of catalytic inhibition cycles with Br species is markedly enhanced at lower flame temperatures because of longer residence time in the reaction zone. The present results at constant strain rates demonstrate that the efficiency of inhibition cycles in the counterflow flame is enhanced at lower flame temperatures, while the residence time remains unchanged with the flame temperature variation. The enhanced efficiency in the counterflow flame is attributed to the slower oxidation, which results in higher concentrations of fuel-originated intermediates in the reaction zone, that are important for regeneration of HBr from Br. The effects of strain rate and CF3Br concentration in the oxidizer are also examined. At a constant flame temperature, the efficiency of inhibition cycles is found to be greater at smaller strain rates and suppressant doping.