GC-MCSPT-A MODIFIED HARD-SPHERE THREE-PARAMETER EQUATION OF STATE WITH GROUP MODEL FOR VLE PREDICTION

The mixing rule for a new group-contribution equation of state was proposed by combining the excess Gibbs energy model with the modified Hard-Sphere Three-Parameter Equation of State designated as the MCSPT equation. Low-and high-pressure vapor-liquid equilibria of 28 binary and 9 ternary systems containing strongly polar substances were predicted by using the interaction parameters of the original and modified UNIFAC model. Predicted results have shown that the proposed GO-MCSPT equation has an extensive applicability with satisfactory accuracy.

1 INTRODUCTIONModels for calculating fluid phase equilibria can be classified into two categories,i.e.the excessGibbs energy model(or the activity coefficient model)and the equation-of-state model.Theformer has achieved a great success in correlating low-pressure phase equilibria of polarmixtures.However,its applicability in the field of high pressure has been limited due to thedifficulty to determine the standard state.