Liquid–Liquid–Vapor Equilibria in Binary Families of SF6, CClF3, C2H3F3, and C2H4 with n-Alkanes

Liquid-liquid-vapor equilibria were determined experimentally for binary and quasi-binary systems which consisted of a low-volatile n-alkane or mixture of n-alkanes with a more volatile component, chlorotrifluoromethane, sulfur hexafluoride, 1,1,1-trifluoroethane, and ethene. From the location of the critical endpoints L2 = L1 + V and L2 + L1 = V of the three-phase curves, the coordinates of the tricritical point and the double critical endpoint of these families were estimated by extrapolation. For the families studied it was found that increasing the carbon number of the n-alkane leads to a transition from type II to type IV to type III fluid phase behavior.