A molecular model for correlating vapor-liquid equilibrium of propane plus hydrocarbon mixtures

Simple analytical expressions are proposed for the calculation of the equilibrium pressure and the mole fractions of both liquid and vapor phases of propane+ hydrocarbon binary mixtures. The new proposed expressions are based on a simple analytical expression for the vapor pressure of pure non-polar fluids, which, for a given temperature, only requires as input the values of the Lennard-Jones molecular parameters and the acentric factor. A properly modified Lorentz-Berthelot mixing rule is used, the interaction parameters being given as simple functions of the temperature and concentration with eight constants for each binary mixture. A different model is proposed to calculate the vapor mole fraction in which four appropriate constants are needed for each mixture. Here, it is shown how the models can reproduce accurately and straightforwardly the vapor liquid equilibrium properties (pressure, liquid mole fraction, and vapor mole fraction) of binary mixtures containing propane.