**HYDROGEN**

HYDROGEN provides high accuracy thermodynamic properties for normal hydrogen (Molar mass =2.01594 kg/kmol) using the Fundamental Equation of State, as described by:

Fundamental Equations of State for Parahydrogen, Normal Hydrogen, and Orthohydrogen

J. W. Leachman, R. T Jacobsen, S. G. Penoncello, and E. W. Lemmon

J. Phys. Chem. Ref. Data 38, 721 (2009)

**Reference State **

** ** h = 3932 kJ/kg, s = 53.37 kJ/kg-K at 298.15 K, 101.325 kPa. The reference state can be changed using the $Reference directive.

**Range of applicability for equation of state**:

13.957 < T < 1000 K

0 < P < 2000 MPa

Note that HYDROGEN provides thermodynamic properties assuming real fluid behavior. The reference state for this formulation is NOT consistent with the enthalpy of formation reference for which specific enthalpy would be 0 at 25C. Use H2 for ideal gas properties of hydrogen consistent with reference states used in combustion calculations.

Transport and surface tension data were fit from the tabular data provided by: P.E. Liley and P.D. Desai, "*Thermophysical Properties of Refrigerants*", ASHRAE, 1993, ISBN 1-1883413-10-9. The valid temperature ranges for these transport data are as follows:

gas phase viscosity: 18 K < T < 500 K

liquid phase viscosity: 14 K < T < 32 K

gas phase thermal conductivity: 14 K < T < 500 K

liquid phase thermal conductivity: 14 K < T < 32 K

__Surface tension data are provided through a correlation developed by:__

G.R. Somayajulu

"A Generalized Equation for Surface Tension from the Triple Point to the Critical Point"

International Journal of Thermophysics, Vol. 9, No. 4, 1988