Formulation of a three-component gasoline surrogate model using laminar burning velocity data at elevated mixture temperatures

Abstract

In this work, a three-component gasoline surrogate model is proposed using the laminar burning velocity data at elevated mixture temperatures. Laminar burning velocity data for a commercially available gasoline + air mixture is obtained using the externally heated diverging channel (EHDC) method for a temperature range of 443–600 K, 1 atmospheric pressure over an equivalence ratio range (0.7–1.4). The measured values are compared with the laminar burning velocities of n-heptane, iso-octane, and methylcyclohexane (MCH) to highlight the variation. Using these components, a new gasoline surrogate model is proposed using an energy-fraction mixing rule and enable its application for engine simulations. The proposed surrogate is validated using a detailed chemical kinetic model of Ranzi (2014). A comparison of the burning velocities (commercial gasoline and proposed gasoline surrogate model) is carried out using a recent Monte-Carlo based correlation (KAUST) for predicting the laminar burning velocity at elevated temperature conditions. A good consistency is observed between the measured laminar burning velocity values of commercial gasoline, its surrogate model, and the predictions of Ranzi (2014) kinetic model. A comparison with KAUST correlation shows a significant disagreement at elevated mixture temperatures for rich mixture conditions. At ϕ = 1.4, and 600 K mixture temperature, the predicted values using KAUST correlation are ~12% higher than the present measurements. A similar over-prediction in the values of temperature exponent, α, is observed for KAUST correlation compared to the predictions of the proposed surrogate model, detailed kinetic model, and experimental measurements.