Modeling non-ideal vapor–liquid phase equilibrium, mass and energy transfer in a binary system via augmentation of computational fluid dynamical methods

A numerical method has been derived to model dynamically varying vapor–liquid phase equilibrium for non-ideal binary systems by augmenting the existing constitutive equations of computational fluid dynamics (CFD). Mass transfer during condensation and vaporization is modeled via equivalently varying source and sink terms; this mass transfer is governed by chemical potential at the liquid–vapor interface. Mass transfer resulting from the chemical potential field is determined by solving the Maxwell–Stefan and energy equations for a time variable pressure, momentum and temperature distribution. Condensation and evaporation are simulated within a multiphase Eulerian framework in such a manner that the components undergoing phase change map the non-ideal phase equilibrium diagram locally at steady state. Equilibrium is assumed at the phase boundary during transient mass transfer prior to reaching global steady conditions.