A Model for Multicomponent Droplet Vaporization in Sprays

A simplified model for multicomponent droplet vaporization is developed and implemented in a multidimensional model for flows, sprays and combustion in engines. The model is applied to study the vaporization characteristics of a multicomponent droplet under Diesel conditions, the distribution of the vapor components in a Diesel spray and the distribution of the components in a Diesel engine. It is shown that for typical warm Diesel engine operating conditions, the droplets vaporize sufficiently rapidly that the stratification of the different components in the spray is not significant. However, under engine starting conditions and, in particular, cold starting conditions, there is a significant stratification of the different components of the fuel. When the species are stratified, the heavier and slower vaporizing components are predicted to be on the periphery of the spray envelope. However, these components also take longer to reach there. The implications of this predicted distribution for cold start in Diesel engines are discussed.