a b s t r a c tThe earlier reported simplified model for multi-component droplet heating and evaporation is generalised to take into account the coupling between droplets and the ambient gas. The effects of interaction between droplets are also considered. The size of the gas volume, where the interaction between droplets and gas needs to be taken into account, is estimated based on the characteristic thermal and mass diffusion scales. The model is applied to the analysis of the experimentally observed heating and evaporation of monodispersed n-decane/3-pentanone mixture droplets at atmospheric pressure. It is pointed out that the effect of coupling leads to noticeably better agreement between the predictions of the model and the experimentally observed average droplet temperatures. In most cases, the observed droplet temperatures lie between the average and central temperatures, predicted by the coupled solution. For the cases reported in this study, the observed time evolution of droplet radii cannot be used for the validation of the model. It is pointed out that the number of terms in the series in the expressions for droplet temperature and species mass fraction can be reduced to just three, with possible errors less than about 0.5%. In this case, the model can be recommended for the implementation into computational fluid dynamics (CFD) codes and used for various engineering applications, including those in internal combustion engines.Crown

The main ideas of the model for droplet heating and evaporation, based on the analytical solution to the heat conduction equation inside the droplet, and its implementation into ANSYS Fluent are described. The model is implemented into ANSYS Fluent using User-Defined Functions (UDF). The predictions of ANSYS Fluent with the new model are verified against the results predicted by in-house research code for an n-dodecane droplet heated and evaporated in hot air. Also, the predictions of this version of ANSYS Fluent are compared with in-house experimental data.

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Modelling of gasoline fuel droplet heating and evaporation processes is investigated using several approximations of this fuel. These are quasi-components used in the quasi-discrete model and the approximations of these quasi-components (Surrogate I (molar fractions: 83.0% n-C 6 H 14 + 15.6% n-C 10 H 22 + 1.4% n-C 14 H 30 ) and Surrogate II (molar fractions: 83.0% n-C 7 H 16 + 15.6% n-C 11 H 24 + 1.4% n-C 15 H 32 )). Also, we have used Surrogate A (molar fractions: 56% n-C 7 H 16 + 28% iso-C 8 H 18 + 17% C 7 H 8 ) and Surrogate B (molar fractions: 63% n-C 7 H 16 + 20% iso-C 8 H 18 + 17% C 7 H 8 ), originally introduced based on the closeness of the ignition delay of surrogates to that of gasoline fuel. The predictions of droplet radii and temperatures based on three quasi-components and their approximations (Surrogates I and II) are shown to be much more accurate than the predictions using Surrogates A and B.

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