Comparative analysis of the Z45 reduced mechanism in predicting methane-hydrogen combustion

This study presents the first comprehensive evaluation of the reduced Z45 chemical mechanism proposed by Zettervall et al. for predicting methane-hydrogen combustion, focusing on ignition delay time, laminar flame velocity, and turbulent flame simulations. The Z45 mechanism is compared to the detailed mechanism GRI-Mech 3.0 and validated across a range of conditions from pure methane to pure hydrogen combustion. The results demonstrate that the Z45 mechanism accurately predicts the ignition delay times for methane at 1, 5, and 10 atm, and the laminar flame velocity for methane-hydrogen mixtures across equivalence ratios of 0.8, 1.0, and 1.2. However, the Z45 mechanism exhibits limitations in predicting autoignition for high-hydrogen-proportion mixtures under relatively high-pressure conditions (5 atm). Sensitivity analysis identifies key reactions driving methane and hydrogen combustion, with reaction H + O 2 ⇒ O + OH being the most sensitive one for methane-hydrogen flame propagation. Turbulent flame simulations of Sandia Flames D, E, and F validate the adaptability of Z45 under various RANS and turbulence-chemistry interaction models, including EDC and PaSR. Computationally, Z45 is approximately six times faster than GRI-Mech 3.0 with the EDC model and five times faster with the PaSR model, while maintaining good accuracy. This study provides a thorough assessment of Z45, demonstrating potentiality for efficient and accurate modeling of methane-hydrogen combustion. • First evaluation of Z45 in premixed laminar and turbulent flames. • Z45 accurately predicts CH 4 ignition delay and CH 4 -H 2 laminar flame velocity. • Sensitivity analysis of Z45 in CH 4 -H 2 flame propagation is performed. • Z45 is applied to RANS simulations of Sandia Flames D, E, and F. • Z45 performs around five to six times faster than GRI-Mech 3.0 with good accuracy.