Methane Combustion in Laminar Diffusion Flames

Abstract

This paper is concerned with methane combustion in laminar diffusion flames. Data on methane concentration distributions in different diffusion flame geometries are correlated against a conserved scalar called mixture fraction. The correlation is used to determine a global methane combustion rate applicable in the rich to stoichiometric regions of laminar diffusion flames. The global rate is consistent with methane disappearance through the forward kinetic step:

CH₄ + H → CH₃ + H₂

with [H] equilibrated according to

$$

on the rich side. This equilibration results from the three-body reaction

$$

which is equilibrated in the region 1.1 ≤ φ ≤ 2.74, 1300 K ≤ T ≤ 2000 K.

These results indicate that initial radical attack on the fuel molecule provides the rate-controlling step for methane combustion.