A discrete multicomponent fuel evaporation model with liquid turbulence effects

A new approach to simultaneously account for finite thermal conductivity, finite mass diffusivity and turbulence effects within atomizing multicomponent liquid fuel sprays has been developed in this study. The main contribution of this paper is to incorporate the liquid turbulence effect in modeling the boundary layer heat and mass resistance during multi-component droplet evaporation. The finite conductivity model is based on an existing two-layer film theory, where the turbulence characteristics of the droplet are used to estimate the effective thermal conductivity. The present paper extends the two-layer film theory formulation to include multi-component mass diffusivities within the droplet liquid phase. In this model four regions are considered: the interior region of the droplet, droplet-side interface, gas-side interface, and the surrounding gas phase. Approximate solutions to the quasi-steady energy and mass transfer equations were used to derive an explicit expression for the heat and mass flux from the surrounding gas to the droplet-gas interface, and within the multi-component droplet. Extension of the model to high pressures using the Peng-Robinson equation of state is also considered. The validation study was carried out for a bi-component decane/hexadecane fuel, followed by application studies of complex gasoline-ethanol blended fuels evaporating in hot gas environments.