The Addition Effects of Methyl Halides on Ethane Ignition Behind Reflected Shock Waves

Abstract

Ignition delay times were measured in C2H6–O2–CH3X(X:Cl, Br or I) mixtures highly diluted with argon behind reflected shock waves. The measurements covered a temperature range of 1200–1900 K and the pressure range of 1.4–2.9 atm. The times were longer than those without CH3X, indicating that CH3X inhibits ethane ignition. This was contrary to the previous results which showed that CH3X promoted methane ignition. To clarify the addition effects of CH3X from the viewpoint of the reaction mechanism, computational analyses were performed in C2H6–O2–CH3Br and CH4–O2–CH3Br mixtures. The analytical results showed that different chain cycles for Br-containing species were formed in the two mixtures. The opposite effects of CH3Br on ethane and methane ignitions could be interpreted in terms of these different cycles.