CALCULATION OF VAPOR LIQUID EQUILIBRIUM AND EXCESS ENTHALPY WITH THE UNIQUAC EQUATION

Abstract

The UNIQUAC equation was used for calculation of vapor liquid equilibrium (VLE)as well as excess enthalpy (h^E). Four sets of binary interaction parameters were applied: first, parameters estimated only from VLE data, then parameters from h^E data for both the original UNIQUAC equation and the Anderson modification, and finally parameters estimated from h^E and VLE data simultaneously. Calculations were performed for seven binary systems with polar components, representing different h^E behavior. The cross-prediction of h^E from VLE data works better than the reversed prediction. The model with parameters estimated simultaneously to both kinds of data can be applied successfully to both kinds of calculations, but it is a compromise between the models estimated from one kind of data.

Keywords:

• Excess enthalpy
• UNIQUAC
• Vapor liquid equilibrium

Notes

^a The units of the parameters are ν₁₂ and [J/mole] and [J/(mole*K)].

The unit for the pressure is kPa and for the temperature is K.

Unit for the parameters is J/mole.

The average at the bottom of the table is weighed with the number of data points for each system. The source column refers to the page in the DECHEMA book for heats of mixing on which the data set may be found.