Effect of molecular structure on incipient soot formation

Abstract A rational threshold soot index (TSI) varying from 0 to 100 is defined for evaluating the onset of soot formation in both premixed and diffusion flames. It is shown that all of the data in the literature on either premixed or diffusion flames, taken by many techniques, are consitent with respect to molecular structure for each of the two types of flames. There is also a closer similarity between the effect of molecular structure on soot formation in premixed and diffusion flames than previously thought. The use of TSI permits one to use all of the literature data to interpret molecular structure effects and thus arrive at rules for predicting the effect of molecular structure for compounds which have not yet been measured or to correlate the results from one experimental sytem with another. If a correlation can be demonstrated between the effect of molecular structure on soot formation in laboratory and in practical systems, then TSIs will be useful to the synfuels program for defining the desired fuel components to be prepared from a given feedstock.