CHEMICAL ASPECTS OF SOOT PARTICLES OXIDATION IN A LAMINAR METHANE - AIR DIFFUSION FLAME

The oxidation of soot in a laminar diffusion flame has been studied experimentally by examining the characteristics of soot particles using laser light scattering. The kinetics mechanisms of oxidation by O2 and OH have been analyzed. The concentrations of OH radicals have been measured by laser-induced fluorescence and calculated, using a partial equilibrium hypothesis. The maximum value of the coefficient of OH collision efficiency obtained is 0.1, and this value is in close agreement with previous published results in other combustion systems. The reaction with OH constitutes the dominant mode of attack unless the O2 concentration is sufficiently high. The breakup of the aggregates that we have observed in the diffusion flame may be explained by an internal burnout of soot particles, due to oxygen molecules, after a surface attack by OH radicals. © 1990.