A reduced mechanism for the combustion of gasoline-ethanol blend on advanced engine combustion modes

A reduced mechanism composed of 144 species and 653 reactions is developed in the present study for simulating the combustion and soot emission of gasoline-ethanol blends on advanced engine combustion modes. The sub mechanism for gasoline combustion is reduced from a detailed mechanism based on the surrogate mixture of n-heptane, iso-octane, toluene, and 1-hexene. A composite approach composed of the path flux analysis and sensitivity analysis is used to perform the reduction. The reduced gasoline mechanism is comprehensively validated against the original detailed mechanism by predicting ignition day, instantaneous temperature, and species mole fraction during the homogeneous auto-ignition and the temperature profiles of perfectly stirred reactor, especially under low-temperature combustion conditions. A reduced ethanol mechanism is also obtained using the same reduction approach and then combined with the reduced gasoline mechanism. By further implementing elementary reactions related to the formation of polycyclic aromatic hydrocarbons (PAHs), the resulting combined mechanism can be used to simulate the ignition, combustion, and PAHs formation of gasoline-ethanol blends with different ratios. The fidelity of the present combined mechanism is comprehensively examined by predicting ignition delay, laminar burning velocity, and PAHs formation of various blends of gasoline surrogates and ethanol. Good agreement is obtained between the predicted properties and the corresponding experimental data.

Automated summary

A reduced mechanism consisting of 144 species and 653 reactions was developed to simulate the combustion and soot emission of gasoline-ethanol blends on advanced engine combustion modes. The reduced mechanisms for gasoline and ethanol were combined to predict ignition delay, laminar burning velocity, and PAHs formation, showing good agreement with experimental data. The fidelity of the combined mechanism was comprehensively examined under different blend ratios.