*Qk* = group area parameters,

Γ*<sup>k</sup>* = group residual activity coefficient,

Γ*k (i)* = residual activity coefficient of group *k* in pure component *i*,

*ϑ<sup>m</sup>* = area fraction of group *m*,

*ψm,k* = group interaction parameter,

*Xm* = mole fraction of group *m* in the mixture,

*am,n* = group interaction parameters obtained from experimental phase equilibrium data.

#### **References**

