Computational Study of the Laminar Reaction Front Properties of Diluted Methanol–Air Flames Enriched by the Fuel Reforming Product

Abstract

The current work investigates the flame structure and the propagation of premixed laminar flame fronts for mixtures of diluted methanol–air enriched by fuel reforming products under spark ignition engine conditions. Two engine concepts were investigated: one with external fuel reforming (EFR) and one with reformed exhaust gas recirculation (R-EGR). Here, the fuel reformate (or syngas) is a mixture of H2, CO, and CO2 with a CO selectivity of 6.5%, which is used to represent the products of methanol steam reforming over a Cu–Mn/Al foam catalyst. The simulations were exercised over a wide range of dilution level and unburned gas temperature at 40 bar with a skeletal chemical kinetic mechanism using zero/one-dimensional codes. Two types of dilution—air and EGR—were compared at the same fuel-to-charge equivalence ratio (ϕ′). The results showed that the knock limit for spark-ignited operation is extended with rising dilution levels, especially when diluted by an R-EGR mixture. Syngas addition also leads to a re...