A REDUCED KINETIC MECHANISM FOR PREMIXED CH3CL/CH4 AIR FLAMES

A reduced kinetic consisting of nine global steps is derived to describe freely propagating flames burning mixtures of methyl chloride and methane in air. The fuel blend contains two fuels with distinct (methyl chloride and methane) thermochemical properties, whose contribution to the radical pool in the flame is different. Our objective is to (1) obtain predictions of flame speeds, particularly for rich flames, and (2) describe the gross chemistry by predicting the concentration profiles of the (a) fuels, (b) oxidizer, (c) products, in particular the C2-containing species (since halogenated flames are generally sooting), and (d) the significant atomic/radical species in the flame. Chlorine atoms available from methyl chloride inhibit the flames, resulting in lower flame speeds. The mechanism is able to predict flame speeds for flames burning rich mixtures of equal molar amounts of methyl chloride and methane in air, and for stoichiometric flames burning methyl chloride and air in the range 30%-67% methyl chloride in the methane/methyl chloride mixture. These predictions are in good agreement with simulations and measurements made in our laboratory, though large discrepancies exist in the measured flame speeds when data due to other investigators is included. The species concentration profiles obtained by using the reduced mechanism are in agreement with those predicted by the detailed mechanism from which it is derived.