n-BUTANE or R600
N-BUTANE and R600 provide high accuracy thermodynamic and transport properties for normal butane (R600, Molar mass = 58.122 g/mol) using the Fundamental (or Helmholtz Free Energy) Equation of State described by:
D. Bucker and W. Wagner
"Reference Equations of State for the Thermodynamic Properties of Fluid Phase n-Butane and Isobutane"
J. Phys. Chem. Ref. Data, Vol. 35, No. 2, 2006
The equation of state is valid for temperatures between 134.895 K (the triple point temperature) and 600 K at pressures up to 70 MPa.
The default reference state is the IIR standard for which: h=200.0 kJ/kg, s=1.0 kJ/kg-K. The reference state can be changed using the $Reference directive.
(Versions prior to 12.010 used the equation of state provided by: Miyamoto, H., and Watanabe, K.,"A thermodynamic property model for fluid-phase isobutane," Int. J. Thermophys., 23(2):477-499, 2002.)
Thermal conductivity data are provided by:
R.A. Perkins, M.L.V. Ramires, C.A. Nieto de Castro, L. Cusco,
"Measurement and correlation of the thermal conductivity of butane from 135 K to 600 K at pressures to 70 MPa,"
J. Chem. Eng. Data 47 (2002).
Viscosity information is provided by:
New Formulation for the Viscosity of n-Butane
Sebastian Herrmann and Eckhard Vogel
Journal of Physical and Chemical Reference Data 47, 013104 (2018)
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
The melting pressure curve (valid for temperatures between 134.86 K and 245 K) is determined from D. Bucker and W. Wagner
Note that N-BUTANE and R600 all provide thermodynamic properties assuming real fluid behavior. Use C4H10 for ideal gas properties of normal butane consistent with reference states used in combustion calculations.