A multicomponent fuel evaporation model was developed to describe diesel fuels. This model is based on the principles of continuous thermodynamics. In contrast to conventional models, each component is not described by discrete relations for energy and mass, but the whole mixture is characterized by a distribution function. In most CFD (computational fluid dynamics)-applications the droplet interior is assumed to be well mixed, this means that composition and temperature are spatially constant inside the droplet. But this assumption is only correct in the case of turbulent mixture with high velocity gradients between spray and surrounding gas, e.g. the area near the nozzle. Due to areas with low relative velocities this formulation is inaccurate and demands a more detailed description of the processes inside the droplet. For these areas the use of a model based on a droplet consisting of several shells is advantageous, because composition and temperature are not spatially constant inside the droplet. The model divides the droplet into a finite number of layers that interchange energy and mass. The implementation of these two models into the CFD-code KIVA-3V implifies the effects of the multicomponent character of the fuel by describing the different areas of the spray more correctly. Both models are compared in single droplet calculations and show a detailed description of evaporation.
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