Radiative properties of char, fly-ash, and soot particles in coal flames. Quarterly report No. 5, September 15--December 15, 1993

The soot formation model formulated in this study is a simple one and considered mainly to determine the order-of-magnitude variations of soot volume formation distribution in a flame. To this extent the model is considered sufficient. First of all, the soot formation is to be coupled closely with the chemical kinetics models. Recent studies suggest that acetylene formed during the combustion of heavy hydrocarbons play a key role in the formation of PAH molecules and in soot inception. Lindstedt and his coworkers (Fairweather et al., 1992; Leung et al., 1992) used a flamelet model and considered global reactions for soot formation. They derived instantaneous relationships between mixture fraction, density, temperature, and gaseous composition of a combusting mixture. Leung et al. (1991) suggested a four-step soot formation/destruction mechanism, and they connected it to the presence of intermediate pyrolysis products, primarily to acetylene. Two separate competing mechanisms were thought to be responsible from soot mass formation: the formation of incipient particles and the particle surface growth due to adsorption of acetylene molecules