Measurements of isobaric heat capacity of R32

The specific isobaric heat capacity (cp) was measured for R32 (difluoromethane) in the gas phase. Thirty-two measurements for R32 were obtained at temperatures from 274 to 353 K and at pressures from 0.65 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 26 mK, and that of the pressure measurements is less than 23 kPa. The expanded uncertainty for cp is estimated to range from 13 to 27 J kg−1 K−1. The experimental data were compared with available equations of state. These data will be essential for improving available models so as to represent more reliable thermodynamic properties of R32 and refrigerant mixtures with R32 that are used for refrigeration and air conditioning systems.

► We measured 32 specific isobaric heat capacity (cp) data for R32 (difluoromethane) in the gas phase. ► The experimental data were obtained at temperatures from 274 to 353 K and at pressures from 0.65 to 2.4 MPa. ► The data were compared with available equations of state. ► The equations have a systematic bias from the data because they were not correlated to the data.