**CARBONDIOXIDE or R744**

CARBONDIOXIDE and R744 both provide high accuracy thermodynamic properties for carbon dioxide using the fundamental equation of state developed by:

R. Span and W. Wagner

*"**A New Equation of State for Carbon Dioxide Covering the Fluid Region from the Triple-Point Temperature to 1100 K at Pressures up to 800 MPa"*,

J. Phys. Chem, Ref. Data, Vol. 25, No. 6, 1996.

The values of specific enthalpy and entropy are, by default, referred to values of 0 at 298.15 K and 101.325 kPa in the ideal gas state. The reference state can be changed using the $Reference directive.

Thermal conductivity is determined in the manner described by:

Vesovic et al., *The Transport Properties of Carbon Dioxide*, J. Phys. Chem Ref, Data, Vol. 19, No. 3, 1990.

The thermal conductivity correlation is valid for temperatures between 200 K and 1000 K for pressures up to 100 MPa.

Viscosity is determined using the correlation provided in:

Fenghour, A., Wakeham, W.A., and Vesovic, V.,

"*The Viscosity of Carbon Dioxide*",

J. Phys. Chem Ref, Data, Vol. 27, No. 1, 1998.

The viscosity correlation is valid for temperature between 200 K and 1500 K for pressures up to 300 MPa.

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 Poin*t"

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

The sublimation pressure curve (valid for temperatures between 70 K and 216.592 K) is determined from R. Span and W. Wagner

The melting pressure curve (valid for temperatures between 216.592 K and 270 K) is determined from R. Span and W. Wagner

Note that CARBONDIOXIDE and R744 provide thermodynamic properties assuming real fluid behavior. Use CO2 for ideal gas properties of carbon dioxide consistent with reference states used in combustion calculations.