Kinematics Viscosity of Several Gases at Temperatures Between 220 K and 375 K, and Pressures up to 3.4 MPa Determined From a Greenspan Acoustic Viscometer

Published

July 18, 2007

Author(s)

Andres Estrada-Alexanders, John J. Hurly

Abstract

The sample gas oscillates between the two chambers at a low frequency dependent on the molecular weight, typically 300 Hz for argon. A complete acoustic model has been developed to fit the complex voltage of the resonance pattern for the Helmholtz mode. This lump-component model is based on a network impedance equivalent circuit of the acoustic resonator. An explicit expression for the impedance main duct end correction can be obtained because of the rounded ends of this duct and both real and imaginary parts of this impedance can be expressed as simple polynomial functions of the viscous penetration length. The values of the coefficients for these polynomials depend on the specific dimensions of the resonator, and are sensitive to resonator s geometrical imperfections. Calibration of the end corrections was obtained at 298.15 K using five reference gases, Ar, He, N2, CH4, C3H8, which viscosity and speed of sound is known. With this calibration, we are estimating an uncertainty in the kinematic viscosity of about 0.5 % as one standard deviation and an uncertainty in speed of sound of few parts in ten thousand, except for very low pressure range where the signal to noise ratio deteriorates and quality factors for the Helmholtz mode are as low as 20 or less.

Citation

Journal of Chemical Thermodynamics

Pub Type

Journals

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Keywords

ab initio, acoustic resonance, frequency scaling factor, ideal gas heat capacity, siloxane, speed of sound

Citation

Estrada-Alexanders, A. and Hurly, J. (2007), Kinematics Viscosity of Several Gases at Temperatures Between 220 K and 375 K, and Pressures up to 3.4 MPa Determined From a Greenspan Acoustic Viscometer, Journal of Chemical Thermodynamics, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=830994 (Accessed December 12, 2024)