AN EQUATION OF STATE FOR THE THERMODYNAMIC PROPERTIES OF R143A (1,1,1-TRIFLUOROETHANE)

Thermodynamic properties of 1,1,1-trifluoroethane (R143a) are expresse d in terms of a 32-term modified Benedict-Webb-Rubin (MBWR) equation o f state. Coefficients are reported for the MBWR equation and for ancil lary equations used to fit the ideal-gas heat capacity, and the coexis ting densities and pressure along the saturation boundary. The MBWR co efficients were determined from a multiproperty fit that used the foll owing types of experimental data: PVT; isochoric, isobaric, and satura ted-liquid heat capacities; second virial coefficients; speed of sound and properties at coexistence. The equation of state was optimized to the experimental data from 162 to 346 K and pressures to 35 MPa with the exception of the critical region. Upon extrapolation to 500 K and 60 MPa, the equation gives thermodynamically reasonable results. Compa risons between calculated and experimental values are presented.