An equation of state formulation of the thermodynamic properties of R134a (1,1,1,2-tetrafluoroethane)

New correlations for the thermodynamics properties of R134a are presented. A classical equation for the molar Helmholtz energy is used with temperature and density as the independent variables. The equation is accurate for both the liquid and vapour phases at pressures up to 70 Pa, and for a temperature range from the triple point to 450 K. Temperatures are given on the new International Temperature Scale of 1990 (ITS 90). The equation was developed by using experimental data for pressure-volume-temperature (PVT) properties, isochoric heat capacity, second virial coefficients, speed of sound and coexistence properties. Comparisons with experimental data and with two other equations of state are given. Ancillary equations representing the saturated liquid and vapour densities and the vapour pressure are also presented.