Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

The isothermal vapour-liquid and vapour-liquid-liquid equilibria of four binary refrigeranthydrocarbon systems were measured using a static-analytic apparatus at temperatures of between (293.0 and 313.2) K and at pressures of up to 6.1 MPa. The two refrigerants that were investigated were trifluoromethane and hexafluoroethane, and the hydrocarbons were methylcyclohexane and toluene. At the temperatures that were investigated, the R-23 + toluene system alone did not exhibit any liquid-liquid immiscibility. The "bird's-beak" phenomenon was observed for all the systems. The experimental data were regressed with the PR MC EOS with the WS mixing rule. Either the NRTL or the UNIQUAC activity coefficient model was used within the WS mixing rule. Both a procedure for the calculation of the critical locus curves from thermodynamic models and an extrapolation technique for determining the mixture critical points from sub-critical co-existence curves were employed. The van Konynenburg and Scott classifications of the four binary systems were discussed.