Acoustic Determination of Dewpoints in Natural Gas Mixtures and RetrogradeCondensates. Annual Report, January-December 1989

摘要

The sonic speed is utilized as a sensitive probe for detecting phase boundariesand critical points of fluids. Location of the boundary is revealed by a discontinuity in the variation of sonic speed with temperature for a sample confined isochorically in a spherical acoustic resonator. The corresponding temperature at which this discontinuity occurs was taken as a phase boundary temperature. This indicator is very pronounced, especially when the system is near the critical condition for which strong local density fluctuations disperse sound and cause the sonic speed to dip sharply toward zero. This research reports on such studies for two pure gases CO2, and C2H6 and one mixture of these two. For each system, data on resonance frequency, amplitude and pressure as a function of temperature were collected under computer control for a series of different loading densities around the critical value. Portions of the phase diagrams revealed by the measurements were recorded in tabular and graphical formats.