Application of a two-sinker densimeter for phase-equilibrium measurements: A new technique for the detection of dew points and measurements on the (methane + propane) system. (August 2016)

• Record Type: Journal Article
• Authors: McLinden, Mark O.; Richter, Markus
• Is Part Of: Journal of chemical thermodynamics. Volume 99(2016:Aug.)
• Page Start: 105
• Page End: 115
• Publication Date: 2016-08
• Subjects: Adsorption -- Dew point -- Gas density -- Measurement -- Methane -- Propane; Thermodynamics -- Periodicals; Thermochemistry -- Periodicals; Thermodynamique -- Périodiques; Thermochimie -- Périodiques; Thermochemistry; Thermodynamics; Periodicals; 541.369
• DOI: 10.1016/j.jct.2016.03.035
• Languages: English
• ISSNs: 0021-9614

Abstract

Graphical abstract: Highlights: A new technique for detecting dew points in fluid mixtures is described. The method makes use of a two-sinker densimeter. The technique is based on a quantitative measurement of sample mass adsorbed onto the surface of the densimeter sinkers. The dew-point density and dew-point pressure are determined with low uncertainty. The method is applied to the (methane + propane) system and compared to traditional methods. Abstract: We explore a novel method for determining the dew-point density and dew-point pressure of fluid mixtures and compare it to traditional methods. The ( p, ρ, T, x ) behavior of three (methane + propane) mixtures was investigated with a two-sinker magnetic suspension densimeter over the temperature range of (248.15–293.15) K; the measurements extended from low pressures into the two-phase region. The compositions of the gravimetrically prepared mixtures were (0.74977, 0.50688, and 0.26579) mole fraction methane. We analyzed isothermal data by: (1) a "traditional" analysis of the intersection of a virial fit of the ( p vs. ρ ) data in the single-phase region with a linear fit of the data in the two-phase region; and (2) an analysis of the adsorbed mass on the sinker surfaces. We compared these to a traditional isochoric experiment. We conclude that the "adsorbed mass" analysis of an isothermal experiment provides an accurate determination of the dew-point temperature, pressure, and density. However, a two-sinker densimeter is required.