Chemical effect of CO2 on the laminar flame speeds of oxy-methane mixtures in the condition of various equivalence ratios and oxygen concentrations

•Chemical effect of CO2 versus oxygen fractions and equivalence ratios was studied.•Changes of contribution of reactions were investigated by sensitivity analysis.•The effect of third body efficiency of CO2 on the laminar flame speed was studied.

The chemical effect of CO2 on the laminar flame speeds of oxy-fuel mixtures was related to the oxygen concentrations and equivalence ratios. In order to study the chemical effect of CO2, we have adopted a premixed oxy-methane flame in the condition of various oxygen concentrations and equivalence ratios. Results show that the chemical effect was smaller than the thermal effect but much bigger than the radiative effect in the calculation domain. The chemical effect of CO2 changed a lot with the oxygen concentrations and equivalence ratios. The effect of third body efficiency of CO2 on the laminar flame speeds of oxy-methane mixtures was discussed. The reaction rate and sensitivity analysis were performed to identify the important reactions which have a third body efficiency of CO2. In addition, the contributions of the elemental reactions were studied with the sensitivity analysis.