Stefan–Maxwell mass transport

Stefan–Maxwell multicomponent transport equations have a lot of appeal because of their symmetry and because the diffusion coefficients are independent of composition for ideal gases. A simple numerical solution method, which can easily be extended to more components, is illustrated for the popular chemical-engineering film, penetration, and boundary-layer models with a particular example of evaporation of acetone and methanol through air. Extension of each model to other geometries and chemical systems is discussed. In the boundary-layer model there is no need to assume that both total concentration and density are constant.