Virial: Virial equations evaluated for pure components are used. The interaction virial coefficient is evaluated if data are available for the mixture; otherwise it is assumed to be b12= (b1 + b2)/2. Third interaction virial coefficients are estimated as follows:
c112 = (2×c1 + b2)/3 and c122 = (c1 + 2×b1)/3.
Peng -Robinson: The Peng-Robinson equation in its original form is used with critical parameters evaluated for the pure components. Interaction parameters kij are assumed to be 0. Reference: D.-Y. Peng, D.B.Robinson, Ind. Eng. Chem., Fundam. 1975, 15, 59.
Redlich-Kwong: The Redlich-Kwong equation with critical parameters evaluated for the pure components components is used. Reference: O. Redlich and J.N.S Kwong, Chem. Rev., 1949, 44, 233 - 244.
Hayden-O'Connell: Computer Calculations for Multicomponent Vapor-Liquid and Liquid-Liquid Equilibria by Prausnitz, Anderson, Greens, Eckert, Hsieh and O'Connell.