The present paper describes a numerical technique to compute phase equilibria of ternary liquid systems. First, particle swarm optimization is used to estimate the binary interaction parameters of the NRTL (Non-Random Two Liquid) and UNIQUAC (Universal Quasi-Chemical) models. We show how the arc-length continuation method allows the calculation of the liquid-liquid equilibrium diagram for any ternary system. A total of seven case studies of industrially important mixtures are described. Both Type I systems (oleic acid-water-ethanol, water-1propanol-toluene, DEC-ethanol-water, water-propionic acid-n-hexane, and water-TMA-benzene) and Type II mixtures (water-1-butanol-nhexane) are discussed. In addition, a system with temperature-dependent behavior (n-hexane-methyl cyclopentane-aniline) is studied. The numerical techniques and the thermodynamic problem involved in this paper are suitable for a first-year graduate-level course in chemical engineering. All computer coding is based either on MATHEMATICA© or MATLAB®. This is an ideal opportunity to introduce graduate students to advanced commands and programming syntax of state-of-the-art mathematical software.
K E Y W O R D Sarc-length continuation, graduate chemical engineering thermodynamics, liquid-liquid equilibrium data, MATHEMATICA© and MATLAB®, NRTL and UNIQUAC models