An experimental and numerical study on the global and detailed kinetics of premixed and nonpremixed flames of chloromethane, methane, oxygen and nitrogen

A comprehensive experimental and numerical study has been conducted on the global flame characteristics and detailed oxidation kinetics of both premixed and nonpremixed flames of chloromethane, methane, oxygen and nitrogen. The experimental phase involves the determination of the laminar burning velocities of premixed flames and of the extinction stretch rates of nonpremixed flames in the counterflow configuration. The experimental results demonstrate and quantify the significant reduction in the burning intensities of these flames with increasing chlorine content. Together with those in the literature, they are then compared with the numerically calculated values obtained with detailed kinetic schemes and transport descriptions. These comparisons, while being fair in most situations, also indicate inadequacies in the existing chlorine-related kinetic sub-mechanisms and/or transport descriptions. As such, the calculated results show a weaker burning intensity than observed and the peaking of the laminar burning velocity on the rich instead of the lean side of stoichiometry. The calculated species profiles within the flame structure allow further identification of the role of the chlorinated species in the flame response, including an increase in the formation of higher-order hydrocarbons indicating a strong tendency to form soot. Finally, based on a one-step overall reaction interpretation, the influences of chlorine content on the responses of premixed and nonpremixed flames are found to be similar.