NRTL

The Non-Random-Two-Liquid model presented by Renon and Prausnitz. This model uses local compositions to represent the excess Gibbs energy.

$$G^E = nRT \cdot \sum_i x_i \frac{\sum_j x_j \tau_{ji} G_{ji}}{\sum_j x_j G_{ji}}$$

with:

$$\tau_{ij} = A_{ij} + \frac{B_{ij}}{T}$$

$$G_{ij} = exp(-C\tau_{ij})$$

Where $A_{ij}, A_{ji}, B_{ij}, B_{ji} \text{ and } C$ are fittable parameters.

1. H. Renon and J. M. Prausnitz, “Local compositions in thermodynamic excess functions for liquid mixtures,” AIChE Journal, vol. 14, no. 1, pp. 135–144, 1968, doi: