association models as Cubic Plus Association (CPA) and SAFT are very good for modeling mixtures including components capable of hydrogen bonding, these are a large part of fluids in industrial plants, I mention water, acids, amines, glycols etc.
These models offer many advantages in terms of accuracy, I have compared water-hydrocarbons VLE calculated with CPA and Peng-Robinson Huron-Vidal (and Wong Sandler) and results from CPA are equivalent or better.
Also Prode Properties includes the data regression utility for calculating VLE/LLE/SLE Kij, Lij (both pairs) interaction coefficients.
This is a really good software and I hope that many engineers will consider with interest this alternative...