A shock-tube and modeling study of syngas ignition delay times in rich CO 2 environment at elevated pressures

Oxy-fuel combustion techniques are crucial for fossil fuel power plants with substantially reduced greenhouse gas emission. The chemical effect of CO 2 as a reactant/product or a third-body is important in modeling oxy-fuel combustion. Many previous kinetic studies focused on evaluating the rate parameters in relevant reactions, but less attention was paid to CO 2 collision efficiencies. In this study, ignition delay time data were measured in a shock-tube facility for stoichiometric syngas mixtures with 50%, 70% and 90% CO in fuel at 1 and 5 atm, diluted in 85% CO 2 bath gas. Among the chemical effect of CO 2, the CO 2 collision efficiency in reaction H+O 2 (+M) = HO 2 (+M) shows a dominantly high sensitivity value to model prediction over the present experimental conditions. Therefore, the CO 2 collision efficiency was evaluated using the current data and a recommended value was reported with uncertainty analysis. Moreover, the CO 2 collision efficiencies in reaction H 2 O 2 (+M) = OH+OH(+M), HCO(+M) = H+CO(+M), H 2 +M = H+H+M and O+O+M = O 2 +M were evaluated using ignition delay time data at higher pressures (40 atm to 200 atm) and recommended CO 2 collision efficiency values were reported with uncertainty analysis. The model with recommended CO 2 collision efficiency values significantly improved prediction performance at 5 atm and was validated over a comprehensive set of syngas ignition delay time and laminar flame speed data.