Measurement of isobaric heat capacity of R125

The specific isobaric heat capacity (cp) was measured for R125 (pentafluoroethane) in the gas phase by using a flow calorimeter. Twelve measurements for R125 were obtained at temperatures from 313 to 333 K and at pressures from 0.8 to 2.4 MPa. Some of them are close to the saturation curve. The expanded uncertainty (k = 2) of the temperature measurements is estimated to be less than 23 mK, and that of the pressure measurements is less than 14 kPa. The expanded uncertainty for cp is estimated to range from 12 to 22 J kg−1 K−1. Also, the experimental data were compared with available equations of state. From the results, it became clear that these data will be essential to improve available models so as to represent more reliable thermodynamic properties of R125 and refrigerant mixtures with R125 that are used for refrigeration and air conditioning systems.