Analysis of Gasoline Surrogate Combustion Chemistry with a Skeletal Mechanism

The engine knock is a major obstacle towards the downsizing and boosting—popular techniques towards meeting the increasingly stringent emission standards— of SI engines. The commercially available gasoline is a mixture of many chemical compounds like paraffins, isoparaffins, olefins and aromatics⁠. Therefore, the modelling of its combustion process is a difficult task. Additionally, the blends of certain compounds exhibit non-linear behaviour in comparison to the pure components in terms of knock resistance and pollutant emission. These facts require further analysis from the perspective of combustion chemistry. The present work analyses the effects of blending different gasoline components on the laminar burning velocity and auto-ignition delay times. A range of pressures, temperatures and equivalence ratios has been considered for this purpose. The open source software Cantera version 2.4.0 has been used for the simulation of laminar burning velocity and ignition delay time. Moreover, the present work proposes a skeletal chemical kinetic mechanism for multicomponent gasoline surrogates. This mechanism has been formed using the open source chemical kinetic reduction code pyMARS. The present work shows that the high temperature ignition delay time is similar for most gasoline component species. However, toluene is significantly less reactive than the rest of the compounds. Some of the blends have been observed to be behaving synergistically with respect to the pure component ignition delay time. On the other hand, the laminar burning velocity of the gasoline surrogates have been seen to be varying linearly with the RON and MON. Therefore, the present work connects the gap between the high temperature combustion chemistry of gasoline surrogates with the associated RON and MON values.