E.W. Lemmon and R.T. Jacobsen
Submitted to the Journal of Physical and Chemical Reference Data (JPCRD)
A new formulation for the thermodynamic properties
of the alternative refrigerant R143a (1,1,1trifluoroethane, CH3CF3) based
upon available experimental data is presented. The formulation provides
for the calculation of densities, heat capacities, sound speeds, energies
and saturation properties using an equation of state explicit in
Helmholtz energy. Ancillary equations are given for the ideal gas heat
capacity, the vapor pressure, and for the saturated liquid and vapor
densities as functions of temperature. Comparisons to available
experimental data are given which establish the accuracy of calculated
properties using this equation of state. The estimated uncertainty of
properties calculated using the new equation is 0.1% in density, 0.5% in
heat capacities, 0.02% in the speed of sound at pressures less than 1
MPa, 0.5% in speed of sound elsewhere, and 0.1% in vapor pressure, except
in the critical region. The equation is valid for temperatures from the
triple point (161.34 K) to 450 K and pressures up to 50 MPa, and can be
extrapolated to 650 K.