A generalized four-parameter equation of state based on corresponding states principle was proposed in a previous paper by Zhang and Xu (1986).In this work

a new mixing rule was derived by analysing the relationship between molecular parameters and bulk properties of fluids. High-pressure vapor-liquid equilibria of 22 binary systems were calculated using the Zhang and Xu equation with the new mixing rule. The calculated pressures and mole fractions of the vapor phase were compared with the experimental values in the literature and also with the results obtained with the LKP corresponding states method. The comparison indicated that the method described here provided better estimates than the LKP method.