Estimation of Multicomponent Diffusion Coefficients for Gas Mixtures

For ideal gases the thermodynamic matrix [F] reduces to the identity matrix and Eq. 4.2.1 becomes 

As discussed briefly in Section 4.1.2, the diffusion coefficients of the binary pairs D-j can be estimated from the kinetic theory of gases or from an appropriate correlation to a reasonable degree of accuracy, particularly for nonpolar molecules. The matrix of diffusion coefficients may therefore be calculated using Eq. 4.2.1 or, for a ternary system, directly from the relations derived below. 

For a ternary system [B] is of order 2 with elements given by 

The inversion of [B] can be carried out explicitly using Equations A.3.9-A.3.10 as shown below. 

It is easy to check that if the binary diffusion coefficients are equal = D, for all 

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