The phase equilibrium behavior of the ternary mixture, containing two completely miscible pairs and one partially miscible binary pair, of ethanol, ethyl acetate, and water was reported in this study. The phase equilibria of this mixture include vapor-liquid equilibria of ethanol-ethyl acetate and ethanol-water binary mixtures; vapor-liquid-liquid equilibrium and vapor-liquid equilibrium (in the miscible region) of water-ethyl acetate binary mixture and ethanol-ethyl acetate-water ternary mixture. All the equilibrium measurements were conducted only with a simple condensed vapor recirculating apparatus. We observed that the equilibrium was difficult to be attained by this simple apparatus in the water-rich region, x(1) > 0.988, of the ethyl acetate-water binary constituent system, since the condensed vapor phase has smaller density and immiscible to the liquid phase. Thus a complete dew point curve can not be constructed. However, this difficulty was overcome by using an isobaric coexistence equation. The binary interaction parameters of the models of UNIQUAC, NRTL, and modified Wilson of Huang and Lee [1994] were obtained based on the various correlations of VLE, LLE, and VLLE of various mixtures of the constituent components. Then those interaction parameters were used to estimate the ternary VLE and LLE of the present mixtures. Comparisons were made between the estimated results and the experimental data. Selection of the best fitted model and interaction parameters can be determined through the various correlations and analysis of the estimated results.
