Mass transfer in continuous mixtures with Maxwell–Stefan diffusion using the adaptive characterization method

The adaptive pseudocomponent characterization method for continuous mixtures was extended to mass transfer problems using the Maxwell–Stefan diffusion model. It is based on the direct quadrature method of moments (DQMoM), using a quadrature rule to discretize the molar fraction distribution of the continuous mixture. The solution method was applied to two one-dimensional mass transfer problems: the transient diffusion in a Loschmidt tube and the steady-state diffusion in a thin film. In the latter, it was showed that the DQMoM equations reduce to an equivalent problem with a fixed characterization and solution methods for linearized theory problems can be employed. For these two problems, the proposed method was verified against the discrete component model (DCM), whose implementation was also verified against existing solutions. Results showed that the adaptive method with five pseudocomponents predicts the mixture properties with maximum relative deviation smaller than 1% when compared to the DCM with 57 components.