GE mixing rule

By equating the Ge from an EOS at zero pressure to that from a GE model, a mixing rule was proposed by Michelsen(1990b) as follows ... 

A new mixing rule has been proposed and tested coupled with SRK EOS and UNIFAC in this work. The new mixing rule, which is obtained by introducing a correction parameter to the Ge from the original UNIFAC in MHV1, is accurate for both binary and ternary gas/large n-alkane systems. The correction parameters have been correlated as a simple function of carbon number for a certain kind of gas/n-alkane system, which is convenient for engineering purposes. 

Finally, we would like to point out that in this work SRK EOS is used to test the new mixing rule, but we believe it is applicable to other cubic EOSs, though the correction factor to GE from UNIFAC may be different. 

Excess volume predictions are extremely sensitive to the value used for the unlike-molecule size parameter. Small deviations must be allowed from the commonly used arithmetic mean mixing rule for size parameters if quantitative results are to be obtained for VE simultaneously with other measurable excess thermodynamic functions (GE and HE). It should be noted that similar conclusions have been drawn for mixtures of globular molecules (8). 

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