Engine Fuel Droplet High-Pressure Vaporization Modeling

Abstract

The objective of this investigation was to characterize the high-pressure vaporization processes of engine fuels, which are too complex in composition to be described with conventional methods. To do so a comprehensive model was developed for the transient vaporization process of droplets of practical engine fuels using continuous thermodynamics in which high-pressure effects are fully considered. Transport equations are derived in a spherical coordinate system for the semi-continuous systems of both gas and liquid phases. A general treatment of vapor-liquid equilibrium is presented, which can be applied with any type of cubic equation of state. Relations for the properties of the continuous species are formulated. The model is further applied to calculate the transient high-pressure vaporization processes of droplets of representative engine fuels—diesel and gasoline. The high-pressure vaporization processes of droplets of two single-component fuels are also predicted for comparison. The results clarify the characteristics of the vaporization processes of engine fuel droplets and indicate the significant effects of fuel type on the vaporization behavior. The comparison with the results of the single-component cases also emphasizes the importance of considering the influence of multicomponent fuels in practical applications.