Heteronuclear Group Contribution Models in SAFT

Following the original first-order thermodynamic perturbation theory of Wertheim heteronuclear models can be proposed where the segments in a given model molecule are arbitrarily different. The earliest works in this direction 

The key difference between the two approaches lies in the treatment of the chain term, in SAFT-y the SAFT-VR chain term is used through the 

A key additional advantage of both SAFT-y and GC-SAFT-VR is that mixtures can be treated in a fully predictive marmer without the need to propose combining rules and adjustable parameters. In this context both methods have been shown to provide a good description of the pressure and composition of mixtures including binary mixtures of alkanes, alkenes, alkanols, namely (alkanes + alkylbenzenes), (alkane + ketones), (alkane + esters), (alkane + adds), (alkanes + amines) and even cases with highly non-ideal behaviour including liquid-liquid equilibrium (LLE) and polymer systems.  

These are promising approaches, which incorporate a detailed molecular model in which groups can be differentiated. In this way, they benefit from advantages of the successful UNIFAC approach, and overcome the difficulties associated with its underlying lattice model. They are accurate over large pressure ranges and can be used consistently for liquid and vapour phases. In addition, as mentioned above, their formulation as continuum fluid theories means that the binary interaction parameters can be determined from pure component data. 

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