Speed-of-sound measurements and ideal-gas heat capacity for 1, 1, 1-trifluoroethane

Speed-of-sound, ideal-gas heat capacity and the second acoustic Virial coefficient have been experimentally studied for 1, 1, 1-trifluoroethane (HFC143a), which is a new refrigerant to substitute chlorodifluoromethane (HCFC22) and/or dichlorodifluoromethane (CFC12). Twenty-eight speed-of-sound values in gaseous 1, 1, 1-trifluoroethane were measured with a spherical resonator for pressure from 200 kPa to 800 kPa along with four isotherms at 293.61, 302.96, 313.19 and 323.18 K, respectively. The ideal-gas heat capacity as well as the second acoustic Virial coefficient has been deduced from the speed-of-sound measurements. The equation of ideal-gas specific heat capacity for 1, 1, 1-trifluoroethane was also proposed, which is effective in temperature range 250-400 K. The experimental uncertainties of temperature, pressure and speed-of-sound for 1, 1, 1-trifluoroethane are estimated to be plus and minus 14 mK, 2.0 kPa and plus and minus 0.0037%, respectively.