A fundamental equation of state has been developed for 1,1,1-trifluoroethan
e (R-143a) using the dimensionless Helmholtz energy. The experimental therm
odynamic propel ty data, which cover temperatures from the triple point (16
1 K) to 433 K and pressures up to 35 MPa, are used to develop the present e
quation. These data are represented by the present equation within their re
ported experimental uncertainties: +/-0.1% in density for both vapor and li
quid phase P-p-T data, +/- 1 % in isochoric specific heat capacities, and /-0.02% in the vapor phase speed-of-sound data. The extended range of valid
ity of the present model covers temperatures from 160 to 650 K and pressure
s up to 50 MPa as verified by the thermodynamic behavior of the isobaric he
at-capacity values over the entire fluid phase.