Modelling of Trifluoromethane (R-23) or Hexafluoroethane (R-116) and Alkane Binary Mixtures using the Group-Contribution whith Association Equation of State

Abstract

The Group-Contribution with Association equation of state (GCA-EOS) has been applied to represent the phase behaviour of binary systems containing either trifluoromethane (R-23) or hexafluoroethane (R-116) with alkanes. The model was successfully fitted to selected literature data, which also formed part of a study into the use of these refrigerants as supercritical fluid extraction solvents. The tuned model was tested against the available experimental data covering the homologous series of C2 to C11 alkanes with either R-23 or R-116, at temperatures of between (193 and 343) K and at pressures of up to 60 MPa. The tuned model provided accurate predictions of the phase behaviour of these systems, including the ability to identify the carbon number of the alkane in the system at which the phase equilibria transformation occurred. The comparison of the model to the experimental data was excellent, with absolute average relative deviations of between (1 and 5) % for both pressure and vapour phase compositions.