Modeling of multi-component fuel vaporization and combustion for gasoline and diesel spray

The present study applied a continuous thermodynamics approach to consider the multi-component nature of petroleum fuels during the vaporization process. A gamma distribution was used to describe the molecular weight of the fuel. The model was first used to study the vaporization of single diesel and gasoline drops. Results showed that the mean molecular weight of the fuel drop kept increasing, indicating that the lighter components vaporized earlier in the process. The present vaporization model was also integrated with an engine simulation code for diesel spray combustion study. Results of diesel spray modeling showed that heavy fuel components survived during the early vaporization process such that the drops in the outer regions of the spray were mostly composed of heavier components. In this study, detailed chemistry was used for diesel combustion modeling. Results showed that good levels of agreement between experiments and predictions were obtained in flame structures and soot distributions. Effects of ambient temperature in the sooting tendency of diesel spray were also predicted by the present model. Under the conditions studied (ρ=14.8kg/m3), soot emissions were not seen for ambient temperature less than 850 K, which is consistent with the concept of low-temperature engine combustion for low emissions.