Thermodynamic Properties of R134a (1,1,1,2-tetrafluoroethane)

The thermodynamic surlace of R134a is expressed in terms of a 32-term modified Benedict· Webb-Rubin (MBWR) equation of state. Coefficients for this equation and for the ancillary equations representing the saturated liquid and vapor densities and the vapor pressure are presented. Temperatures are given on the new International Temperature Scale· of 1990 (lTS 90). The MBWR coefficients were obtained using a multi-property fit that used experimental data for PVT properties, isochoric heat capacity, second virial coefficients, speed of sound, and coexistence properties, including new measurements not used in previous formulations. The formulation is applicable to both the liquid and vapor phases at pressures up to 70 MPa, and for a temperature range from the triple point to 450 K. The accuracy of the equation of state is estimated to be ±0.2% in density, ±1.0% in constant-volume heat capacities, and ±0.6 % in the sound velocity, except in the critical region, based on comparisons with experimental data. In addition, a comprehensive bibliography of experimental data for R 134a is presented.