**R123**

R123 provides thermodynamic properties for R123 using the fundamental equation of state described by Reiner Tillner-Roth in ** Fundamental Equations of State,** Shaker, Verlag, Aachan, 1998. The equation is a refit of the modified Benedict-Webb-Rubin equation established by B.A. Younglove and M.O. McLinden, "An International Standard Equation of State for the Thermodynamic Properties of Refrigerant R123," Journal of Physical and Chemical Reference Data, Vol. 23, No. 5, pp. 731-779, 1994. Ancillary routines are from Younglove and McLinden. The equation of state is valid for temperatures between 166K and 525K at pressures lower than 40 MPa.

The values of specific enthalpy and entropy are, by default, referred to 200 kJ/kg and 1.00 kJ/kg-K, respectively for the state of saturated liquid at 273.15 K. The reference state can be changed using the $Reference directive.

__Viscosity and thermal conductivity are calculated using the correlations presented by:__

Y. Tanaka and T. Sotani,

"Thermal Conductivity and Viscosity of 2-2-dichloro-1,1,1-trifluoroethane, (HCFC-123),

Int. J. of Thermophysics, Vol. 17, No. 2, pp. 293-328, 1966.

The correlation is valid for temperatures between 253 K and 425 K.

__Surface tension data are from: __

Okada, M. and Higashi, Y.,

"R123--Thermodynamic and physical properties, International Institute of Refrigeration, Paris, (1995).