A numerical model of chemical kinetics of combustion in a turbulent flow reactor

Calculations with a numerical model incorporating detailed chemical kinetics, hydrodynamic motion, and energy transport in a turbulent flow reactor have been compared with experimental results of Dryer and Glassman. A reaction mechanism, including 19 chemical species and 56 reactions, for the reaction of dilute moist carbon monoxide in air and of dilute methane in air was established for the temperature range 1000-1350 K. HO₂ and H₂O₂ were found to be important in the mechanism for both carbon monoxide and methane oxidation, and CH₂O, CH₃O, C₂H₆, and C₂H₄ were found to be important in methane oxidation. Important steps in the reaction mechanisms have been identified, and optimal values for some key reaction rates have been determined. The branching ratio between reaction 3, H + O₂ = OH + O, and reaction 17, H + O₂ + M = HO₂ + M, was found to be important in determining the length of the induction period in each experiment. At 1100 K the value determined for k₁₇ was 2.6 × 10¹⁵ cm⁶/(mol² s). Decomposition reaction 7 for HCO, HCO + M = H + CO + M, was found to play a key role in methane oxidation, providing the major path for production of carbon monoxide. At 1100 K, k₇ was found to be 2.4 × 10¹⁰ cm³/(mol s). Even though the reaction studied was extremely oxygen rich, recombination of methyl radicals and subsequent oxidation of the ethane thus formed was found to provide a major route for methyl radical destruction. The assumption that plug flow conditions prevail in the turbulent flow reactor was examined and found to be valid under most practical conditions.