Measurements of PVTx properties of refrigerant mixture HFC-32 + HFC-125 in the gaseous phase

The experimental 156 PVTx properties of an important binary refrigerant mixture, HFC-32 (difluoromethane) + HFC-125 (pentafluorethane), have been measured for three compositions, i.e., 50, 60, and 80 wt% HFC-32, by a constant-mass-method coupled with expansion procedure in an extensive range of temperatures T from 320 to 440 K, of pressures P from 1.8 to 5.3 MPa, and of densities ρ from 50 to 124 kg·m^-3. The experimental uncertainties of the present measurements are estimated to be within ±7 mK in temperature. ±2 kPa in pressure. ±0.2% in density and ±0.02 wt% of HFC-32. The sample purities are 99.998 wt% for HFC-32 and 99.99 wt% for HFC-125. Seventy-eight second and third virial coefficients for temperatures from 320 to 440 K have been determined by the present measurements.