Fluid Phase Equilibria in Binary Systems of Trifluoromethane + Phenylalkanes

In this study, the phase behaviour of asymmetric systems consisting of the refrigerant, trifluormethane (R23) and 7 members of the family of the alkylbenzenes is investigated. Alkylbenzenes are used as lubricants in refrigeration cycles for special applications at very low temperature. Equilibrium data were obtained using a synthetic method in the temperature range 250…400 K and in the pressure range 1.5…15 MPa. The investigated systems all exhibit III phase behaviour, according to the classification of van Konynenburg and Scott, except for the system CHF3+ i-propylbenzene, which is of type II. For 4 systems the experimental data were modelled with two cubic EoSs: Soave-Redlich-Kwong (SRK) and Peng-Robinson (PR) and coupled with classical van der Waals mixing rules. A single set of binary parameters was used to predict the global phase behaviour of the system for a large range of pressure and temperature. Although the model is simple, it is able to represent correctly the complex phase equilibria of the systems studied in this work.