Reduced chemical kinetics mechanism for syngas combustion and NOx formation

Chemical kinetics and computational fluid-dynamics (CFD) analysis were performed to evaluate the combustion of syngas derived from biomass solid feedstock in a micro-pilot ignited supercharged dual-fuel engine under lean conditions. For this analysis, a new reduced syngas chemical kinetics mechanism was developed and validated by comparing the ignition delay and laminar flame speed data with those obtained from experiments and other detail chemical kinetics mechanisms available in the literature. The reaction sensitivity analysis was conducted for ignition delay at elevated pressures in order to identify important chemical reactions that govern the combustion process. We found that H02+OH=H20+02 and H202+H=H2+H02 reactions showed very high sensitivity during high-pressure ignition delay times and had considerable uncertainty. The chemical kinetics of NOx formation was analysed for H2/CO/C02/CH4 syngas mixtures by using premixed laminar flame speed reactors. The new mechanism showed a very good agreement with experimental measurements and accurately reproduced the effect of the equivalence ratio on NOx formation. Finally, the new mechanism was used in a multidimensional CFD simulation to predict the combustion of syngas in a micro-pilot-ignited supercharged dual-fuel engine and results were compared with experiments. The mechanism showed the closest prediction of the in-cylinder pressure and the rate of heat release (ROHR).