Phase Equilibrium Measurements of Fluid Mixtures at High Pressures

Phase equilibrium relations at high pressures are required in practical use, such as in the design and operation of supercritical fluid extraction. High-pressure phase equilibrium measurements of fluid mixtures cannot simply generate the reliable data. In the present review, the reference data are first mentioned. For the development of mixing rules in equations of state for fluid mixtures, reliable standard phase equilibrium data of fluid mixtures at high pressures are required as reference of standard. Next, recent researches on the phase equilibrium measurements at high pressures are reviewed by classifying the types of the experimental apparatus: static, circulation, static-circulation, flow, synthetic, and mass balance. All experimental methods and apparatus seem consistent, with the exception of some special cases. The experimental data obtained by the different experimental methods and apparatus should agree one another. In the high-pressure phase equilibrium measurements of fluid mixtures just a minor poor treatment in the experiment causes a large error in the final experimental results, and all experimental treatments should be carefully consistent to establish the reliable consistent data.