HELIUM
Helium provides thermodynamic properties for normal fluid (not superfluid) Helium using the fundamental equation of state developed by Ortiz Vega:
Diego Orlando Ortiz Vega
A New Wide Range Equation of State for Helium-4
PhD Thesis, Chemical Engineering
Texas A&M University, August 2013
https://oaktrust.library.tamu.edu/handle/1969.1/151301
There are a few typographical errors in this work that should be noted. The sign for h and b in Eqn (75) should be positive, not negative as displayed when used with the coefficients in Table 4. Coefficient N4 in Equation (109) should also be positive. Coefficients s0/R and h0/(RT0) need to be adjusted to provide the desired reference state.
The specific enthalpy and entropy values provided by the equation of state are referenced to 0 for saturated liquid at the normal boiling point (4.23 K).
The equation of state is valid for temperatures between the lower l-point temperature (2.172 K) and 1500 K for pressures up to 2000 MPa.
Viscosity data:
Arp, V.D., McCarty, R.D., and Friend, D.G., "Thermophysical Properties of Helium-4 from 0.8 to 1500 K with Pressures to 2000 MPa," NIST Technical Note 1334, Boulder, CO 1998.
Thermal Conductivity Data:
Hands, B.A. and Arp, V.D.,"A Correlation of Thermal Conductivity Data for Helium," Cryogenics, 21(12):697-703, 1981.
Surface tension data are provided using the information in:
Mulero, A., Cachadina, I, and Parra, M.
"Recommended Correlations for the Surface Tension of Common Fluids"
J.Phys. Chem Ref. Data, Vol. 41, No.4, 2012
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The current helium correlation was implemented in version 10.049. Previous versions used an equation of state based on data from McCarty and Arp as provided by Reiner Tillner-Roth, Fundamental Equations of State, Shaker, Verlag, Aachan, 1998 with ancillary equations provided by R.D. McCarty and V.D. Arp, "A New Wide Range Equation of State for Helium", Advances in Cryogenic Engineering, Vol. 35, pp. 1465-1475, 1990. The range of applicability of the thermodynamic properties is from the lambda point temperature 2.1768 K to 1500 K at pressures up to 100 MPa.
Note that there is a missing plus sign before the first summation in equation (2) of the McCarty and Arp paper and the X in table 2 should be defined as (T-TC)/(T1-TC).
The older equation of state is provided for backward compatibility with substance name Helium_MA. Note that the values of specific enthalpy and entropy in this implementation are referred to values of 0 at 298.15 K and 101.325 kPa, which differs from the reference state in the current Helium implementation.