An Optimized Methane Reaction Model for Oxyfuel Combustion

Abstract

Pressurized oxyfuel combustion technology is a potential solution for reducing greenhouse gas emissions by carbon capture and storage while burning hydrocarbon fuels. Numerous experiments on CH4 ignition delay times and laminar flame propagation velocities at high pressures and CO2 atmosphere dilution have been reported, contributing to the improvement of current CH4 combustion kinetic models. However, existing mainstream models produce significantly larger prediction errors for syngas ignition delay time data, especially under oxyfuel combustion conditions. Motivated by the observation, an optimized CH4 model was developed based on a comprehensive set of experimental data, including 2205 ignition delay time, 3344 laminar flame speed, and 200 species profile measurements and balanced the predicted performance of the syngas. A novel sampling strategy was developed and embedded in the optimization algorithm to improve the computational efficiency. The optimized rate constants fall reasonably within the estimated uncertainty range. Prediction performance of the optimized model was evaluated and compared to four well-established models. The optimized model showed considerably improved results, providing a better balance between the prediction of ignition delay time and laminar flame speed data. The kinetic reasons for the improved performance were examined and discussed.