Speed of sound, ideal-gas heat capacity at constant pressure, and second virial coefficients of HFC-227ea

The speed of sound of the gaseous 1,1,1,2,3,3,3-heptafluoropropane (HFC-227 ea) was measured for temperatures from 273 to 333 K and pressures from 26 t o 315 kPa with a cylindrical, variable-path acoustic interferometer operati ng at 156.252 kHz. The uncertainty of the speed of sound was less than +/-0 .05%. The ideal-gas heat capacity at constant pressure and the second acous tic virial coefficients were determined over the temperature range from the speed of sound measurements. The uncertainty of the ideal-gas heat capacit y at constant pressure was estimated to be less than +/-0.5%. The ideal-gas heat capacity at constant pressure results and second virial coefficients calculated from the present speed of sound measurements were compared with the available data. (C) 2001 Elsevier Science B.V. All rights reserved.