Fire Safety Science Digital Archive

A systematic study of the effects of soot formation on the production of carbon monoxide (CO) in laminar diffusion flames has been conducted. Increased amounts of soot have been observed to result in larger concentrations of CO in the higher regions of the flames. Comparisons of CO state relationships as a function of local equivalence ratio show distinct effects as the local soot volume fraction is varied. Fuel rich regions exhibit lower CO mole fractions as soot concentration increases, whereas higher CO mole fractions are observed under fuel lean conditions. Radiative quenching and competition between soot and CO for OH is examined. Competition for OH is a plausible mechanism that can be responsible for the high CO emissions from fires. Radiative quenching does not seem to play a significant role in fuel rich regions but can be important under fuel lean conditions.