Modeling benzene and naphthalene formation in a premixed propylene flame

The Utah Surrogate Mechanism was used to model a fuel-rich, non-sooting premixed laminar flame of propylene at 5000 Pa with an equivalence ratio of 2.32. The simulation results were found to be satisfactory in comparison with the experimental data. For example, the measured concentration profiles of the fuel, oxidizer, inert and major products were successfully reproduced. The predictive ability of the model for soot precursors is one of the major foci of this paper; the maximum acetylene and benzene concentrations were predicted within 15% and 30% of the measured values, respectively. The formation of benzene and naphthalene has been critically examined to identify the major reaction pathways of these smallest aromatics, the chemistry of which initiates the growth of PAH species. Combination reactions involving resonant stabilized species such as propargyl, allyl and benzyl radicals were found to be the most important formation pathways for aromatics. Reactions involving benzene have profound impacts on those of naphthalene; however, other formation routes bypassing benzene via reactions of C3+C4 were identified to be the major formation pathways of the higher aromatic species.