Superequilibrium O Concentrations and Prompt NO Formation in Laminar Premixed Methane-Air Flames

Abstract

Superequilibrium concentrations of oxygen atoms which enhance the production of prompt NO in laminar premixed methane-air flames are usually computed using elaborate flame codes. This paper presents a simple method to compute superequilibrium O atom concentrations and simplifies the prompt NO mechanism using steady state relationships such that the flamefront NO production depends solely on the rates of just 3 reactions. The results show that the contribution of the N₂O mechanism to the total NO increases dramatically with pressure and that the Fenimore mechanism is more important than the Zeldovich and N₂O pathways in the cooler regions of the flame.

Keywords:

• NO _x
• prompt NO
• N₂O mechanism
• superequilibrium O
• laminar premixed flames
• methane

Notes

∗Address for correspondence: A. C. Leadbetter Inc., 110 Arco Dr, Toledo, OH 43607.