q-Quadratic mixing rule for cubic equations of state

• The q-Mixing rule is a new nonquadratic mixing rule.
• Correlations between species evaluated by means of the q-product.
• The proposal is a generalization of van der Waals mixing rules.
• The q-Mixing rule has been tested by evaluating vapor–liquid equilibrium.

We introduce a new nonquadratic mixing rule that models correlations between species by means of the q-product of mole fractions, instead of the ordinary product. The use of the q  -product is a procedure adopted within the nonextensive statistical mechanics formalism in the generalization of the central limit theorem for strongly correlated systems. The proposal is a generalization of the ordinary van der Waals quadratic law that is recovered when the so-called nonquadraticity binary parameter takes the limit qij→1qij→1. The proposed q-mixing rule has been tested by evaluating vapor–liquid equilibrium at different temperatures for systems containing alcohol, hydrocarbons and CO2, species that yield departures from ideality. Two distinct approaches, the Akaike Information Criterion and the F-test, were used to compare the q-mixing rule and the van der Waals mixing rule.