Experimental and Numerical Study of the Laminar Burning Velocity and Pollutant Emissions of the Mixture Gas of Methane and Carbon Dioxide

This paper presents the experimental and numerical study of the laminar burning velocity and pollutant emissions of the mixture gas of methane and carbon dioxide. Compared to previous research, a wider range of experimental conditions was realized in this paper: CO(2) dilution level up to 60% (volume fraction) and equivalence ratio of 0.7–1.3. The burning velocities were measured using the heat flux method. The CO and NO emissions after premixed combustion were measured by a gas analyzer placed 20 cm downstream of the flame. The one-dimensional free flames were simulated using the in-house laminar flame code CHEM1D. Four chemical kinetic mechanisms, GRI-Mech 3.0, San Diego, Konnov, and USC Mech II were used in Chem1D. The results showed that, for laminar burning velocity, the simulation results are all lower than the experimental results. GRI Mech 3.0 showed the best agreement when the CO(2) content was below 20%. USC Mech II showed the best consistency when the CO(2) content was between 40 and 60%. For CO emission, these four mechanisms all showed a small error compared with the experiments. When CO(2) content is higher than 40%, the deviation between simulation and experiment becomes bigger. When the CO(2) ratio is more than 20%, the proportion of CO(2) does not affect CO emission so much. For NO emission, when the CO(2) content is 40%, the results from simulation and experiment showed a good agreement. As the proportion of CO(2) increases, the difference in NO emissions decreases.