DERIVATION AND APPLICATION OF THE STEFAN-MAXWELL EQUATIONS

The Stefan-Maxwell equations represent a special form of the species momentum equations that are used to determine species velocities. These species velocities appear in the species continuity equations that are used to predict species concentrations. These concentrations are required, in conjunction with concepts from thermodynamics and chemical kinetics, to calculate rates of adsorption/desorption, rates of interfacial mass transfer, and rates of chemical reaction. These processes are central issues in the discipline of chemical engineering. In this paper we first Outline a derivation of the species momentum equations and indicate flow they simplify to the Stefan-Maxwell equations. We then examine three important forms of the species continuity equation in terms of three different diffusive fluxes that are obtained from the Stefan-Maxwell equations. Next we examine the structure of the species continuity equations for binary systems and then we examine some special forms associated with N-component systems. Finally the general N-component system is analyzed using the mixed-mode diffusive flux and matrix methods.