Vapor-Liquid Equilibrium, Coexisting Phase Densities, and Surface Tension

VLE/Interfacial Tension Apparatus -- click to enlarge

Vapor-liquid-equilibrium (VLE) measurements are the most fundamental data for mixtures and are thus analogous to p-V-T measurements for pure fluids. These data consist of bubble and/or dew point pressures and the compositions (and sometimes the densities) of the coexisting liquid and vapor phases. They are the data needed to fit the adjustable "mixing coefficient(s)" in mixture equations of state.

Historically, vapor-liquid equilibrium measurements have proven to be very valuable in the characterization of the thermodynamic surface of fluids. These measurements are particularly useful for the purpose of mathematically representing the saturation boundary of a fluid. A state of the art vapor-liquid equilibrium apparatus is used for measurements of vapor pressure, coexisting phase densities, coexisting phase compositions (for multi-component fluids), and surface tension.

The measurement capabilities of the apparatus are as follows:

Temperature Range: 218-423 K

Pressure Range: 0-14 MPa
Accuracy: 0.03 K in temperature, 0.1% of the pressure range, 0.5 kg/m³ in density, 0.2 dyne/cm in surface tension, and 0.5 mole percent in composition.
Applications: Pure and multi-component fluid systems over wide ranges of temperature and pressure.

The apparatus has been used for vapor-liquid equilibrium measurements on a variety of potential alternative refrigerant systems as well as some hydrocarbon systems. A sampling of journal articles pubished on this research is given below.

C. D. Holcomb, and L.J. Van Poolen, "Coexisting Densities and Vapor Pressures for Refrigerant R-143 from 314-401 K with New Critical Point Property Estimations," Fluid Phase Equil. 100, 223 (1994).
V.G. Niesen, L.J. Van Poolen, S.L. Outcalt, and C.D. Holcomb, "Coexisting Densities and Vapor Pressures of Refrigerants R-22, R-134a, and R-124 at 300 to 395 K," Fluid Phase Equil. 97, 81 (1994).
C.D. Holcomb, V.G. Niesen, L.J. Van Poolen, and S.L. Outcalt, "Coexisting Densities and Vapor Pressures of Refrigerants R-32 and R-152a at 300 to 385 K," Fluid Phase Equil. 91, 145 (1993).

Small Volume Dual-Cell Dew-Bubble Point

Small Volume Dual-Cell Dew-Bubble Apparatus -- click to enlarge

A dew-bubble point apparatus is being designed and constructed for the measurement of. Construction and initial testing are expected to be completed by . The experimental capabilities of the apparatus will be as follows:

Temperature Range: 218-423 K
Pressure Range: 0-14 MPa
Accuracy: 0.03 K in temperature, 0.1% of the pressure range, 0.5 kg/m³ in density, 0.2 dyne/cm in surface tension, and 0.5 mole percent in composition.
Applications: Pure and multi-component fluid systems over wide ranges of temperature and pressure.

Contact:

Stephanie L. Outcalt
NIST
Physical and Chemical Properties Division
Experimental Properties of Fluids Group
Mail Stop 838.07
325 Broadway
Boulder, CO 80305-3328 USA

	+1-303-497-5786
	+1-303-497-5224


Physical & Chemical Properties Division	Chemical Science & Technology Laboratory	NIST Boulder Labs	NIST Homepage

Vapor-Liquid Equilibrium, Coexisting Phase Densities, and Surface Tension

Temperature Range: 218-423 K

Pressure Range: 0-14 MPa

Accuracy: 0.03 K in temperature, 0.1% of the pressure range, 0.5 kg/m³ in density, 0.2 dyne/cm in surface tension, and 0.5 mole percent in composition.

Applications: Pure and multi-component fluid systems over wide ranges of temperature and pressure.

C. D. Holcomb, and L.J. Van Poolen, "Coexisting Densities and Vapor Pressures for Refrigerant R-143 from 314-401 K with New Critical Point Property Estimations," Fluid Phase Equil. 100, 223 (1994).

V.G. Niesen, L.J. Van Poolen, S.L. Outcalt, and C.D. Holcomb, "Coexisting Densities and Vapor Pressures of Refrigerants R-22, R-134a, and R-124 at 300 to 395 K," Fluid Phase Equil. 97, 81 (1994).

C.D. Holcomb, V.G. Niesen, L.J. Van Poolen, and S.L. Outcalt, "Coexisting Densities and Vapor Pressures of Refrigerants R-32 and R-152a at 300 to 385 K," Fluid Phase Equil. 91, 145 (1993).

Small Volume Dual-Cell Dew-Bubble Point

Temperature Range: 218-423 K

Pressure Range: 0-14 MPa

Accuracy: 0.03 K in temperature, 0.1% of the pressure range, 0.5 kg/m³ in density, 0.2 dyne/cm in surface tension, and 0.5 mole percent in composition.

Applications: Pure and multi-component fluid systems over wide ranges of temperature and pressure.

Contact:

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Vapor-Liquid Equilibrium, Coexisting Phase Densities, and Surface Tension

Temperature Range: 218-423 K

Pressure Range: 0-14 MPa

Accuracy: 0.03 K in temperature, 0.1% of the pressure range, 0.5 kg/m3 in density, 0.2 dyne/cm in surface tension, and 0.5 mole percent in composition.

Applications: Pure and multi-component fluid systems over wide ranges of temperature and pressure.

C. D. Holcomb, and L.J. Van Poolen, "Coexisting Densities and Vapor Pressures for Refrigerant R-143 from 314-401 K with New Critical Point Property Estimations," Fluid Phase Equil. 100, 223 (1994).

V.G. Niesen, L.J. Van Poolen, S.L. Outcalt, and C.D. Holcomb, "Coexisting Densities and Vapor Pressures of Refrigerants R-22, R-134a, and R-124 at 300 to 395 K," Fluid Phase Equil. 97, 81 (1994).

C.D. Holcomb, V.G. Niesen, L.J. Van Poolen, and S.L. Outcalt, "Coexisting Densities and Vapor Pressures of Refrigerants R-32 and R-152a at 300 to 385 K," Fluid Phase Equil. 91, 145 (1993).

Small Volume Dual-Cell Dew-Bubble Point

Temperature Range: 218-423 K

Pressure Range: 0-14 MPa

Accuracy: 0.03 K in temperature, 0.1% of the pressure range, 0.5 kg/m3 in density, 0.2 dyne/cm in surface tension, and 0.5 mole percent in composition.

Applications: Pure and multi-component fluid systems over wide ranges of temperature and pressure.

Contact:

Accuracy: 0.03 K in temperature, 0.1% of the pressure range, 0.5 kg/m³ in density, 0.2 dyne/cm in surface tension, and 0.5 mole percent in composition.

Accuracy: 0.03 K in temperature, 0.1% of the pressure range, 0.5 kg/m³ in density, 0.2 dyne/cm in surface tension, and 0.5 mole percent in composition.