Development of a 5-component gasoline surrogate model using recent advancements in the detailed H2/O2/CO/C1-C3 mechanism for decoupling methodology

Abstract

In the present work, a 5-component gasoline surrogate chemical kinetic mechanism has been developed and validated. The first novelty of this mechanism is that a recently advanced H2/O2/CO/C1 detailed sub-mechanism is adopted for accurately predicting the laminar flame speeds over a wide range of operating conditions and a recently advanced C2-C3 detailed sub-mechanism is used due to its potential benefits on accurate flame propagation simulation in order to overcome the drawbacks in the original decoupling methodology. The second novelty of this mechanism is that the sub-mechanisms of propyne and allene which are important for soot formation from non-aromatics have been improved significantly. For each of the five gasoline surrogate components (iso-octane, n-heptane, iso-hexane, 1-hexene, and toluene) a skeletal sub-mechanism, which determines the simulation of ignition delay times, is constructed for species C4-Cn. The five skeletal sub-mechanisms are coupled with the new C2-C3 and H2/O2/CO/C1 detailed sub-mechanisms. Together with a reduced NOx (oxides of nitrogen) sub-mechanism, the 5-component gasoline surrogate chemical kinetic mechanism has 214 species and 1233 reactions, which are feasible currently for CFD simulation of gasoline engine combustion, emissions, and knock. The new H2/O2/CO/C1 and C2-C3 detailed sub-mechanisms were validated with selected experimental data of ignition delay times, laminar flame speeds, and important species profiles in the literature. The reaction rate constants of the five skeletal sub-mechanisms were optimized in this work to match available experimental data of either pure fuels or fuel blends, including real gasoline fuels. The validation results show that the prediction accuracy of the 5-component gasoline surrogate chemical kinetic mechanism of the present work can be less than 5% for various fuel blends under a pressure range of 1.0 80.0 bar, a temperature range of 300 1260 K, and an equivalence ratio range of 0.5 2.5.