Optimized Chemical Kinetics for Modeling Natural Gas Combustion

Improved understanding of natural gas combustion chemistry, leading to the formulation and validation of a detailed reaction mechanism capable of quantitatively accounting for and modeling high temperature natural gas ignition and flame phenomena, is needed to serve as a basis for designing improved combustion devices with respect to efficiency and emissions. We have carried out a systematic optimization procedure, starting from a critically evaluated set of 177 elementary reactions, to derive a thermochemical and kinetic parameter set (GRI-Mech 1.2) that successfully accounts for a set of laboratory combustion property measurements (47 flame speeds, shock tube ignition delay times, and species profiles) over wide temperature, pressure, and composition ranges. In our presentation we will describe this optimization procedure, and present the results of validation studies on the combustion of methane and related fuels. We will also report on the performance of reduced mechanisms, derived from the full one for specific conditions to use in applications requiring shorter kinetic parameterization, and on the results of extending the optimization procedure to a detailed mechanism describing NOx formation and reburning.