**R134a**

R134a provides thermodynamic properties for R134a using the fundamental equation of state developed by R. Tillner-Roth and H.D. Baehr, *An International Standard Formulation for the Thermodynamic Properties of 1,1,1,2-Tetrafluoroethane (HFC-134a) for Temperatures from 170 K to 455 K and Pressures up to 70 MPa*, J. Phys. Chem, Ref. Data, Vol. 23, No. 5, 1994.

The values of specific enthalpy and entropy are, by default, set to 0 kJ/kg and 0 kJ/kg-K at -40°C (and -40°F). Another common reference state is the IIR reference for which h and s are 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 is correlated with a relation developed by__:

Marcia Huber, Arno Laesecke, and Richard A. Perkins at NIST-Boulder, submitted in January 2003 to Industrial Engineering and Chemistry Research;

__Liquid phase thermal conductivity data are from the generalized correlation described by__

M.J. Assael, N.K. Dalaouti, A.A. Griva, and J.H. Dymond,

"Viscosity and Thermal Conductivity of Halogenated Methane and Ethane Refrigerants",

IJR, Vol. 22, pp. 525-535, 1999.

These property correlations are applicable over the same range as the equation of state.

Gas-phase viscosity: 230 K to 475 K

Gas-phase thermal conductivity: 230 K to 475 K

__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

A computationally more efficient but potentially less accurate formulation for R134a properties is available with fluid name R134a_mh.