Numerical study of the effect of CO₂/H₂O dilution on the laminar burning velocity of methane/air flames under elevated initial temperature and pressure

Abstract

Diluents have an essential effect during combustion. Discovering the influence of CO2 and H2O as diluents on laminar burning velocity (LBV) is helpful for combustion control and optimization. In this study, CH4/air/CO2/H2O mixtures were investigated and validated using the FFCM‐Mech 1.0 over extensive boundary conditions. The chemical effects of the diluents CO2 and H2O were separated using a decoupling method. It was found that an increase in initial temperature promotes the chemical effects, while an increase in initial pressure does the opposite. In addition, the inhibiting effect of CO2 on LBV is stronger than that of H2O. Sensitivity, mole fraction, and rate of production (ROP) analyses were used to reveal that the sum of the chemical effects of adding CO2 and H2O separately was greater than the chemical effects of adding equal amounts of CO2 and H2O simultaneously. This paper not only investigates the effect of CO2 and H2O on the LBV under wide boundary conditions, but also offers a valuable guide for studying the operating conditions and intensity settings of exhaust gas recirculation (EGR) and theoretical guidance for further research on the combination of EGR and in‐cylinder water injection technology.

Deflagration Dynamics of Methane–Air Mixtures in Closed Vessels at Elevated Temperatures

“…The intricate interplay between heat release, flame stretch, and diffusive processes at varying temperatures necessitates comprehensive experimental and numerical analyses. In the literature [21], some authors also investigated the dilution effect of carbon dioxide and water on the laminar burning velocity of methane-air flames, as well as the coupling effect between CO 2 and H 2 O. It was concluded that the strongest chemical effects were observed with the simultaneous supplementation of CO 2 and H 2 O.…”