Electrolyte-NRTL Model by Chen

Both the long-range and the short-range interactions have to be taken into account for the calculation of the phase equilibrium behavior in multicomponent electrolyte mixtures. While the long-range interactions can be accounted for by the Debye-Hiickel term, the short-range interactions can be described by the local 

However, the influence of long-range interactions has to be taken into account by a term describing the Debye-Hiickel theory. For this term, in the general case the density and the dielectric constant of the mixed solvent have to be determined (see Eq. (7.49)). As the reference state of the electrolyte components refers to the infinitely diluted solution in pure water, the Debye-Hiickel term must be corrected by the so-called Born term, which takes into account the difference between the dielectric constants of water and the solvent mixture [14]  

For the ionic radius n, the default value n = 3 10 m has been recommended. Thus, the Gibbs energy of a system described by a local composition model can be expressed as 

For the local concentrations 0y (concentration of species i in direct neighborhood to the central species j), the following equations can be set up  

Additionally, for the cells with a molecule at center, Chen et al. [15] postulates local electroneutrality, that is. 

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