The experimental pressure-volume-temperature-composition (PVTx) properties of binary refrigerant, HFC-32 (difluoromethane)+HFC-134a (1,1,1,2-tetrafluoroethane) have been measured by means of a constant-mass method coupled with expansion procedure. A total of 178 pressure-volume-temperature-composition relationships were measured for the 20, 40, 60, and 80 wt% HFC-32 mixtures at 320-440 K, 1.5-6.2 MPa, and 61-183 kg/m3 by an apparatus of constant-mass-method with experimental errors of ±7 mK in temperature, ±2 kPa in pressure, ±0.1% in volume, and ±0.2% in composition, respectively. The sample purities are 99.998 wt% for HFC-32 and 99.99 wt% for HFC-134a. The second and third virial coefficients have been determined from the measurements. The enthalpy and entropy values in the gaseous phase are derived from the virial equations for each composition which can be used for the evaluation of the compressors for this binary refrigerant system in the refrigeration machine.
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