Numerical Simulation of Methane Combustion in Two-Layer Porous Media Under Oxy-Fuel Condition

The combination of oxy-fuel and porous media combustion can considerably broaden the lean-burn limit while significantly improving combustion stability. It is foreseeable that some of the deficiencies under oxyfuel condition will be overcome. In this paper, a two-layer porous burner model is established, in which the CH 4 skeletal kinetic mechanism and a two-temperature equation model are adopted for calculation purposes. Corresponding experiments are set up to verify the accuracy of the mathematical model. After that, the stable range and temperature field under oxy-fuel conditions, as well as the resulting CO emissions, are studied in detail. The stable range can be substantially broadened by adjusting the equivalence ratio and the oxygen fraction in the combustion-supporting gas. Stable combustion can be achieved under an inlet velocity of 2–29 cm/s and a thermal load of 36–834 kW/m 2 . Properly preheating the premixed gas can also effectively broaden the stable range, while the flame temperature will not rise sharply. The difference in the peak temperature between the solid and gas phases is in the range of 170–200 K. In addition, the peak temperature of the solid phase is located 0.8–1.2 cm downstream that of the gas phase. Extremely low or high equivalence ratios and oxidizer ratios need to be avoided, as they can introduce large amounts of CO emissions. When the flame peak temperature is controlled between 1300 and 1700 K, the CO emissions can reach values lower than 5 ppm.