Stephan-Maxwell equation

Anisothermal Transport Across a Phase Boundary. Once we know the effect of temperature on equilibrium position, we need know only its effects on diffusivities and the condensation coefficient to complete our task. The Stephan-Maxwell equation states that diffusivity in the vapor increases with the square root of the absolute temperature. In the condensed phase the temperature effect is expressed by an Arrhenius-type equation. 

In the case of transport in gases, Stokes law applies only if particle radius a is much larger than the mean free path (0.065 /im in air at 20°C and 1 atm). For smaller particles and molecules, a correction factor must be applied to Stokes law [30]. Alternatively, the friction coefficient may be approximated using Eq. 3.21 and the Stephan-Maxwell equation for diffusion in an ideal gas mixture composed of solute of molecular weight Mx in a carrier of molecular weight M2... 

In addition to this, the three-dimensional mathematical model of heat and mass transfer [3, 4] has been developed. Stephan-Maxwell equation was used for mass transport calculations in gas channels and gas diffusion layers. Proton transport in membrane and electrocatalytic layer was described by Nemst-Planck equation. The diffusion and electroosmosis of water were taken into account for membrane potential distribution. 

R. Krishna and G. L. Standart, A Multicomponent Film Model Incorporating a General Matrix Method of Solution to Maxwell-Stephan Equations, AIChE I, 22, pp. 383-389,1976. 

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