Mass transfer interdiffusion coefficient

Mutual Diffusivity, Mass Diffusivity, Interdiffusion Coefficient Diffusivity is denoted by D g and is defined by Tick s first law as the ratio of the flux to the concentration gradient, as in Eq. (5-181). It is analogous to the thermal diffusivity in Fourier s law and to the kinematic viscosity in Newton s law. These analogies are flawed because both heat and momentum are conveniently defined with respec t to fixed coordinates, irrespective of the direction of transfer or its magnitude, while mass diffusivity most commonly requires information about bulk motion of the medium in which diffusion occurs. For hquids, it is common to refer to the hmit of infinite dilution of A in B using the symbol, D°g. 

For the interdiffusion in the pores of membrane support, the individual mass-transfer coefficient is... 

Diffusion coefficients are important for mass-transfer operations (see Chapter 8, Mass Transfer ). There are several differently defined diffusion coefficients (self-diffusion coefficient, interdiffusion [or mutual diffusion] coefficient, intradiffusion [or tracer diffusion] coefficient) this can be a source of confusion. These are delineated in standard references [15, 68, 69]. 

Model calculations were carried out by the example of a parabohc dependence of the interdiffusion coefficient for a binary system. The efficiency of the method was demonstrated for significant perturbations of the model experimental concentration profile up to 10% with respect to the exact values. The additional smoothing component of the discrepancy functional expressed as squared entropy production can be set to solve any inverse problems of heat and mass transfer. The suggested method, unlike the Matano-Boltzmann method, can be generalized to multicomponent systems with arbitrary sample configurations. 

---