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A new model for drop evaporation has been developed, including the effect of gas convection according to the film theory, by relating the thermal and diffusional film thicknesses to the gas stream Reynolds number. The model solves the species, momentum and energy conservation equations in a radial coordinate system, accounting explicitly for the gas density dependence on temperature and vapour concentration. The model has been tested under a wide range of gas temperatures, Reynolds numbers and liquid species and the results have been compared against experimental data available in the scientific literature and with the predictions from the classical extended film model. The present model, together with relieving some of the physical inconsistencies of the classical models, which become not negligible at high gas temperature, also shows a rather good agreement with the experimental data for the selected operating conditions.

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Most of the currently used models for droplet heating and evaporation are based on the assumption that droplets are perfect spheres. At the same time the shapes of many observed droplets in engineering applications are far from spherical. We have studied the influence of droplet non-sphericity on their heating and evaporation, approximating droplet shapes as prolate and oblate spheroids. The previously developed exact solutions to the heat and mass transfer equations for the gas phase surrounding a spheroidal droplet have been used as boundary conditions for the solutions to these equations in the liquid phase. The temperature gradients inside and at the surface of the droplets, and the changes in their shape during the heating and evaporation process have been taken into account. The effects of surface tension and droplet motion on droplet heating and evaporation are ignored. The results are applied to the analysis of heating and evaporation of an n-dodecane fuel droplet in Diesel engine-like conditions. The effect of droplet nonsphericity is shown to be relatively small for the evaporation time of these droplets with initial eccentricities 2/3 ≤ ǫ ≤ 1.5.

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