**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