On mild and vigorous oxidation of mixtures of chlorinated hydrocarbons in droplet burning

Droplet burning with mixtures of nonane and the heavily chlorinated tetrachloroethane (TECA) was studied computationally using a quasi-steady, spherical diffusion flame model of simultaneous fuel vaporization, pyrolysis, and combustion, with detailed transport and a semidetailed reaction mechanism. The dependence of the droplet burning rate on the chlorine content was examined through the TECA concentration in the fuel mixture. It is shown that the model predicts reasonably well the influence of chlorine content on the d²-law burning rate constant experimentally determined in a previous study, and that the sharp decrease in the burning rate for fuel mixtures with C1/H ratio around and greater than unity is caused by the reduction of heat release, as well as through the chemical inhibition by chlorine. The computational results also suggest the beneficial effect of water vapor in promoting burning.