Sooting tendencies premixed flames

For the flames described in Table 8.7, Harris and Weiner [74] obtained the results shown in Fig. 8.20, where the increase of soot volume fraction is plotted as a function of time. Thus, temperature measurements revealed that Flame 3 has the lowest temperature, Flames 2 and 4 are of equal, and somewhat higher temperature, and Flame 1 has the highest temperature. These results supply quantitative proof that in premixed flames the tendency to soot decreases with increasing flame temperature. Also of importance is the fact that Flame 2, which has toluene as a fuel constituent and the same equivalence ratio as that of Flame 4 for pure ethene, gives the same soot volume fraction as Flame 4... 

The results presented in Fig. 17 for diffusion flames and those from shock tubes clearly indicate that fuel structure does indeed play a role in a fuel s tendency to form particulates—in significant contrast to the results observed in premixed flames. One may conclude, then, that a fundamental knowledge of a fuel s pyrolysis chemistry [51, 76] will allow one to predict its relative tendency to soot with respect to the results presented in Fig. 17. For example, cyclohexadienes are known to dehydrogenate to benzene during pyrolysis and, indeed, the data in... 

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