Experimental Study of the Laminar Flame Speeds of the CH4/H2/CO/CO2/N2 Mixture and Kinetic Simulation in Oxygen-Enriched Air Condition

The experimental study on the laminar flame speeds of the CH4/H-2/CO/CO2/N-2 mixture was carried out in oxygen-enriched air condition. The laminar flame propagation velocities of the blended gas were measured in a range of equivalence ratios (from 0.6 to 1.4) and oxygen concentrations (from 21 to 33%) using a Bunsen flame. Comparisons between the experiments and calculations show that the GRI Mech 3.0 mechanism can well predict the laminar flame speed of the blended gas in oxygen-enriched conditions. The laminar flame propagation velocities were enhanced by the increasing oxygen concentration, while the reaction pathway of fuel changed little. The effects of each species of the CH4/H-2/CO/CO2/N-2 mixture on the laminar flame speeds were discussed. Results show that the laminar flame speed is promoted by the increase of H-2 and CO, while the laminar flame speed is decreased by the increasing CH4, CO2, and N-2 concentrations. The inhibition effect of CO2 on the laminar flame speed is bigger than that of N-2, which is due to the difference in the properties of CO2 and N-2.