**R134a_mh**

The thermodynamic properties of refrigerant R134a are provided by Martin-Hou equation of state (A.I.Ch.E. Journal, 1:142, 1955) based on thermodynamic information from McLinden et al., *Measurement and Formulation of the Thermodynamic Properties of R134a and 123*, ASHRAE Trans., Vol. 95, No.2, 1989.

The values of specific enthalpy and entropy are referred to 0 for saturated liquid at -40 C (F).

Fluid R134a will provide properties using the international standard formulation and more accurate results at high densities.

**Range of applicability for transport function correlations**:

Gas-phase viscosity: 230 K to 475 K

Liquid-phase viscosity: 230 K to 375 K

Gas-phase thermal conductivity: 230 K to 475 K

Liquid-phase thermal conductivity: 230 K to 375 K

The Martin-Hou equation of state is valid for states in which the density is less than 1.5 times the critical density. Properties in the vicinity of the critical point and at high pressures may be inaccurate. Properties in the subcooled region are determined by assuming the fluid is incompressible.

Surface tension data were fit to data obtained from the NIST REFPROP 6 program (M.O. McLinden, S.A. Klein, E.W. Lemmon and A.P. Peskin, Physical and Chemical Properties Division, National Institute of Standards and Technology, Boulder, CO 80303, 1995. The range of applicability of the data are from 170 K to the 374 K.

NOTE: This fluid is provided for backward compatibility. Use of R134a (rather than R134a_MH) is recommended because it is based on a more accurate equation of state.