NA-04-1-1 – Viscosity Measurements and Model Comparisons for the Refrigerant Blends R-410A and R-507A PDF

Wide-ranging viscosity measurements of the blends R-410A (0.5 R-32 + 0.5 R-125 by mass) and R-507A (0.5 R-143a + 0.5 R-125 by mass) were carried out in a torsional crystal viscometer at two subcritical and three supercritical isotherms between 300 and 420 K with pressures up to 82 MPa. Considerable conductances were observed in the blend containing difluoromethane (R-32). Therefore, reference viscosity measurements of the blend R-410A were carried out at saturated-liquid conditions between 240 K and 310 K with a sealed gravitational capillary viscometer, because in that instrument the sample is not exposed to an electric field. The measurement results are compared with values estimated via the extended-corresponding-states model in NIST Standard Reference Database 23 (REFPROP, version 7.0) and with literature data. For both blends, the results obtained with the torsional crystal viscometer agree with the predicted viscosities within the estimated experimental uncertainty of the instrument at low sample conductances. The deviations increase systematically with the sample conductance. The data for R-410A obtained with the capillary viscometer agree with the estimated viscosities within their experimental uncertainty. Literature data deviations range from –18% to 5% for this blend and from –9% to 14% for R-507A, while the R-507A-measurements of this work agree with the model viscosities within ±4%.

Units: SI