An efficient liquid film vaporization model for multi-component fuels considering thermal and mass diffusions

An improved multi-component quasi-dimensional vaporization model for wall film was proposed with considering the finite thermal and mass diffusions within the liquid film. In the improved model, high order polynomials were introduced to describe the profiles of the temperature and component concentrations within the film. The results show that the predictions from the present quasi-dimensional model agree well with those predicted by the one-dimensional model. By investigating the effect of the thermal and mass diffusions on the vaporization of the diesel film, it is found that the thermal diffusion plays a more dominant role in the multi-component film vaporization. Compared with the linear temperature model with the linear temperature and uniform component distributions in the film, the application range of the quasi-dimensional model is considerably wider and the computational error is significantly reduced. Finally, the linear temperature, quasi-dimensional, and one-dimensional models were integrated into a Computational Fluid Dynamics (CFD) code for the simulations of film vaporization in the flow over a backward facing step and in a practical diesel engine. The results indicate that the improved model gives much better agreement with the one-dimensional solutions than the linear temperature model, while maintaining high computational efficiency under different operating conditions. (C) 2016 Elsevier Ltd. All rights reserved.