An Optimized Methane Reaction Model for Oxyfuel Combustion

Pressurized oxyfuel combustion technology is a potentialsolutionfor reducing greenhouse gas emissions by carbon capture and storagewhile burning hydrocarbon fuels. Numerous experiments on CH4 ignition delay times and laminar flame propagation velocities athigh pressures and CO2 atmosphere dilution have been reported,contributing to the improvement of current CH4 combustionkinetic models. However, existing mainstream models produce significantlylarger prediction errors for syngas ignition delay time data, especiallyunder oxyfuel combustion conditions. Motivated by the observation,an optimized CH4 model was developed based on a comprehensiveset of experimental data, including 2205 ignition delay time, 3344laminar flame speed, and 200 species profile measurements and balancedthe predicted performance of the syngas. A novel sampling strategywas developed and embedded in the optimization algorithm to improvethe computational efficiency. The optimized rate constants fall reasonablywithin the estimated uncertainty range. Prediction performance ofthe optimized model was evaluated and compared to four well-establishedmodels. The optimized model showed considerably improved results,providing a better balance between the prediction of ignition delaytime and laminar flame speed data. The kinetic reasons for the improvedperformance were examined and discussed.