ACOUSTIC PROBING OF PHASE-EQUILIBRIA IN NEAR-CRITICAL FLUIDS

Phase behavior is a fundamental aspect of supercritical fluids. We des cribe a simple acoustic method for the investigation of fluid phase eq uilibria. The method is used to investigate pure components, and binar y and ternary mixtures. In contrast to highly accurate speed of sound measurements in homogeneous fluids, we investigate the vapor-liquid bo undaries of mixtures. The reciprocal of the speed of sound was measure d at selected near-critical isotherms. For mixtures, isopleths are mea sured to establish the course of the critical line. All data for pure components are in good agreement with the literature where available. Limitations of the acoustic method in determining phase equilibria are discussed. (C) 1998 Elsevier Science B.V. All rights reserved.