Improved Phenomenological Soot Model for Multicomponent Fuel Based on Variations in PAH Characteristics with Fuel Type

Abstract

Integration of a skeletal polycyclic aromatic hydrocarbon (PAH) model with a toluene reference fuel (TRF) oxidation model was used to develop a skeletal TRF-PAH model. A phenomenological soot model, coupled with the new TRF- PAH model, was modified based on the experimental observation that fuels with different molecular structures produce PAHs and soot in different ways. The new TRF-PAH model was validated against experimental data for the relevant PAHs for the oxidation/pyrolysis of toluene in a jet-stirred reactor, flow reactor, and shock tube. The results show that the PAH model can reproduce the experimental data for the major species concentrations. The predicted benzene concentration in the oxidation of alkanes and aromatic hydrocarbons indicates that the molecular structure of the fuel significantly affects the PAH formation pathway. The improved soot model was validated against measured soot yields from the pyrolysis of toluene, toluene/n-heptane mixtures, and toluene/isooctane mixtures in a shock tube, as well as toluene oxidation. The results show that the predicted soot yields obtained using the new soot model are in reasonable agreement with the experimental data over a wide operating range. Finally, the soot model was used to predict the soot emissions from a diesel engine fueled with TRF20. The results indicate that the TRF-PAH combustion model and the new soot model can reproduce the combustion and emission characteristics well.