We report experimental measurements of
three-phase equilibria in the system (heptane + carbon dioxide
+ water) obtained with a quasi-static analytical apparatus with
compositional analysis by means of gas chromatography. The
apparatus was calibrated by an absolute area method and the
whole measurement system was validated by means of
comparison with the published literature data of the system
(heptane + carbon dioxide). The compositions of the three
phases coexisting in equilibrium were measured along five
isotherms at temperatures from (323.15 to 413.15) K with
pressures ranging from approximately 2 MPa to the upper
critical end point pressure at which the two nonaqueous
phases became critical. The experimental results have been compared with the predictions of the statistical associating fluid
theory for potentials of variable range. The unlike binary interaction parameters used here are consistent with a previous study for
a ternary mixture of a different n-alkane, while the alkane−water binary interaction parameter is found to be transferable and the
alkane−carbon dioxide binary interaction parameter is predicted using a modified Hudson-McCoubrey combining rule.
Generally, good agreement between experiment and theory was found