An international standard formulation for the thermodynamic properties of 1,1,1-trifluoroethane (HFC-143a) for temperatures from 161 to 450 K and pressures to 50 MPa
Ew. Lemmon et Rt. Jacobsen, An international standard formulation for the thermodynamic properties of 1,1,1-trifluoroethane (HFC-143a) for temperatures from 161 to 450 K and pressures to 50 MPa, J PHYS CH R, 29(4), 2000, pp. 521-552
A new formulation is presented for the thermodynamic. properties of refrige
rant 143a (1,1,1-trifluoroethane, CH3-CF3) based upon available experimenta
l data. The formulation can be used for the calculation of density, heat ca
pacity, speed of sound, energy, and saturation properties using an equation
of state explicit in Helmholtz energy. Ancillary equations are given for t
he ideal gas heat capacity, the vapor pressure, and for the saturated liqui
d and vapor densities as functions of temperature. Comparisons to available
experimental data are given that establish the accuracy of calculated prop
erties using this equation of state. The estimated uncertainties of propert
ies calculated using the new equation are 0.1% in density, 0.5% in heat cap
acities, 0.02% in the speed of sound for the vapor at pressures less than 1
MPa, 0.5% in the speed of sound elsewhere, and 0.1% in vapor pressure, exc
ept in the critical region. The equation is valid for temperatures from the
triple point temperature (161.34 K) to 450 K and pressures up to 50 MPa, a
nd can be extrapolated to 650 K. It has been accepted as an international s
tandard formulation for the properties of R-143a by the International Energ
y Agency-Annex 18. (C) 2001 by the U.S Secretary of Commerce on behalf of t
he United States. All rights reserved.