N. Elvassore et al., GROUP-CONTRIBUTION EQUATION OF STATE FOR THE PREDICTION OF VAPOR-LIQUID-EQUILIBRIA OF MIXTURES CONTAINING HYDROFLUOROCARBONS AND ALKANES, Industrial & engineering chemistry research, 37(8), 1998, pp. 3105-3111
This work is aimed to present and validate a thermodynamic model that
enables the prediction of vapor-liquid equilibria of refrigerant mixtu
res of alkanes and hydrofluorocarbons, in the temperature and pressure
ranges of interest for refrigeration cycles and heat pump application
s. A modified Redlich-Kwong-Soave equation of state is used with Huron
-Vidal mixing rules and a modified UNIFAC group-contribution approach
for calculating the component infinite-pressure activity coefficients.
A new classification of functional groups is suggested, and the value
s of interaction parameters between groups are provided. These paramet
ers are regressed from selected binary vapor-liquid equilibrium data.
A good regression is obtained for all group pairs, with a maximum root
-mean-square deviation on relative pressure residuals of 1.86%, The pr
oposed method is totally predictive since only the structure, critical
constants, and vapor pressure of pure components are needed in order
to calculate thermodynamic properties of refrigerant mixtures. Results
for a number of binary and ternary mixtures are reported and compared
to available experimental data.