AN INTERNATIONAL STANDARD EQUATION OF STATE FOR THE THERMODYNAMIC PROPERTIES OF HFC-125 (PENTAFLUOROETHANE)

An 18-coefficient modified Benedict-Webb-Rubin equation of state for H FC-125 (pentafluoroethane) has been developed, Correlations of vapor p ressure and saturated liquid density are also presented. This equation of state has been developed using experimental data for the relations hip of pressure-volume-temperature of fluid, saturation properties, is ochoric heat capacity data, and speed of sound data. The equation of s tate is valid in the superheated gaseous phase and the compressed liqu id phase at pressures up to 68 MPa, densities to 1700 kg/m(3), and tem peratures from the triple point (172.52 K) to 475 K. This equation of state has been selected as an international standard formulation for H FC-125 based on an evaluation of the available equations of state by A nnex 18 of the International Energy Agency. (C) 1998 American Institut e of Physics and American Chemical Society. [S0047-2689(98)00304-3].