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5. Debye equation of state for fluid helium-3.

Author

Yonghua Huang, Guobang Chen, and Arp, Vincent

Subjects
HELMHOLTZ equation, THERMODYNAMICS, PHONONS, HELIUM, THERMAL conductivity, VISCOSITY, PROPERTIES of matter
Abstract

An equation of state for ³He using the Helmholtz potential function has been developed. The lower limit of the equation of 0.01 K is safely above the superfluid transition at 0.0026 K. The upper limit of 60 K is approximately the upper limit of available ³He property measurements. The new state equation form is based on Debye function which goes smoothly to zero in the limit of zero temperature and reduces to the ideal gas in the limit of zero density and/or very high temperature. The equation combines (a) necessary temperature-independent compressibility terms at the lowest temperatures, (b) terms describing the linear specific heat of a Fermi fluid below 1 K, (c) terms describing the phonon excitations which begin above about 1 K, and (d) terms which attempt to fit the conventional critical point thermodynamics at 3.3157 K and 114 604 Pa. State properties, e.g., p-V-T relations, specific heats, thermal expansion, sound velocity, etc., are determined from the Helmholtz energy by standard thermodynamics. Transport properties, e.g., thermal conductivity and viscosity, are not obtained in this work. [ABSTRACT FROM AUTHOR]

Published
2006
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6. Thermophysical properties of Helium-4 from 0.8 to 1500 K with pressures to 2000 MPa

Author

Arp, Vincent D and Mccarty, Robert D

Subjects
Inorganic And Physical Chemistry
Abstract

Tabular summary data of the thermophysical properties of fluid helium are given for temperatures from 0.8 to 1500 K, with pressures to 2000 MPa between 75 and 300 K, or to 100 MPa outside of this temperature band. Properties include density, specific heats, enthalpy, entropy, internal energy, sound velocity, expansivity, compressibility, thermal conductivity, and viscosity. The data are calculated from a computer program which is available from the National Institute of Standards and Technology. The computer program is based on carefully fitted state equations for both normal and superfluid helium.

Published
1989

10. Refrigeration of Superconducting Rotating Machinery.

Author

NATIONAL BUREAU OF STANDARDS BOULDER COLO CRYOGENICS DIV, Arp,Vincent D., NATIONAL BUREAU OF STANDARDS BOULDER COLO CRYOGENICS DIV, and Arp,Vincent D.

Abstract

Recent work at the NBS Cryogenics Division in three areas related to helium refrigeration is summarized: (1) Analysis is given of a possible high pressure refrigeration cycle which offers in principle a reduced component size, but which turns out to be impractical because of expansion engine inefficiencies. (2) Exact equations for flow of a real fluid are derived and applied to problems of fluid flow near the critical point, as may occur with some helium-cooled superconducting systems, and (3) Three new equations of state for helium are given, each using different state variables, to eliminate the need for iterative techniques in helium refrigeration cycle and fluid flow analysis. (Author)

Published
1973

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