| A reaction model was developed for the simulation of the entire combustion process for transportation fuels starting with the pyrolysis and oxidation of the fuel to the formation of soot.; The fuel consumption process can be explained by cascading alkyl radical decompositions combined with olefin chemistry with appropriate kinetic parameters assigned to important reaction classes. Those reaction classes include hydrogen abstraction and thermal decomposition for the fuel consumption, and beta scission, alkyl radical isomerization, hydrogen abstraction by O2, thermal decomposition, and radical addition then decomposition for olefin chemistry. To make the mechanism extendable to even larger paraffins, generic rates of reactions involving paraffins, olefins and alkyl radicals in the same reaction class were selected and tabulated.; The proposed final mechanism for the combustion simulation of commercial fuels comprises 208 species and 1087 reactions and implements a detailed reaction network for the pyrolysis and oxidation of surrogate fuels up to normal dodecane. Reactions involving paraffins, olefins, and alkyl radicals in the same reaction class were assigned generic rates. Rates of reactions involving other unsaturated species had been carefully estimated by consulting findings in the literature for same or similar reactions with adjustments in statistical factor and activation energy. In order to correctly predict the level of benzene, the reactions involving allyl radical and its related species were modified and the ability to predict these species has been greatly improved.; Simulations using the final mechanism were found to adequately fit the experimental data of fourteen premixed flames burning surrogate fuels including benzene, n-heptane, isooctane, n-decane, methyl cyclohexane, n-dodecane and other smaller fuels for equivalence ratios between 1.0 (stoichiometric) to 3.1 (fuel rich) and pressures ranging from 20 torr to 760 torr.; Two soot formation models using particle dynamics with one-dimensional nucleation mode directly coupled with gas phase chemistry were tested on three ethylene and three methane laminar premixed flames. These models correctly predict the effect of C/O ratio on soot formation and predict the soot characteristics with satisfactory accuracy. The predicted values of soot volume fraction are within a factor of three and those of particle diameter are within a factor of two of the experimental data. |
