Investigation of the Effect of Hydrogen and Methane on Combustion of Multicomponent Syngas Mixtures using a Constructed Reduced Chemical Kinetics Mechanism

This study investigated the effects of H 2 and CH 4 concentrations on the ignition delay time and laminar flame speed during the combustion of CH 4 /H 2 and multicomponent syngas mixtures using a novel constructed reduced syngas chemical kinetics mechanism. The results were compared with experiments and GRI Mech 3.0 mechanism. It was found that mixture reactivity decreases and increases when higher concentrations of CH 4 and H 2 were used, respectively. With higher H 2 concentration in the mixture, the formation of OH is faster, leading to higher laminar flame speed and shorter ignition delay time. CH 4 and H 2 concentrations were calculated at different pressures and equivalence ratios, showing that at high pressures CH 4 is consumed slower, and, at different equivalence ratios CH 4 reacts at different temperatures. In the presence of H 2 , CH 4 was consumed faster. In the conducted two-stage sensitivity analysis, the first analysis showed that H 2 /CH 4 /CO mixture combustion is driven by H 2 -based reactions related to the consumption/formation of OH and CH 4 recombination reactions are responsible for CH 4 oxidation. The second analysis showed that similar CH 4 -based and H 2 -based reactions were sensitive in both, methane- and hydrogen-rich H 2 /CH 4 mixtures. The difference was observed for reactions CH 2 O + OH = HCO + H 2 O and CH 4 + HO 2 = CH 3 + H 2 O 2 , which were found to be important for CH 4 -rich mixtures, while reactions OH + HO 2 = H 2 O + O 2 and HO 2 + H = OH + OH were found to be important for H 2 -rich mixtures.