VISCOSITIES OF HFC-32 AND HFC-32 LUBRICANT MIXTURES/

A modified capillary tube method has been used to measure viscosities for HFC-32 over a temperature range From -20 to 90 degrees C and a pre ssure range from 0.1 to 5.3 MPa, and for the liquid mixtures of HFC-32 with a synthetic polyolester oil at temperatures from 20 to 75 degree s C and oil mass fractions from 0.44 to 1. Estimated uncertainties in the measured viscosities do not exceed +/- 1.2 and +/- 1.8% for the pu re fluocarbon and the mixtures, respectively. It is found that viscosi ty isotherms for HFC-32 at subcritical temperatures exhibit a minimum with increasing pressure, with the viscosity decreasing as much as 10% relative to its value al one atmosphere. Correlations are presented f or dilute gas viscosities, excess viscosities, and saturated liquid an d vapor viscosities. These correlations are shown to fit our data with in experimental uncertainties. For HFC-32/lubricant mixtures, a Free-v olume viscosity model has been applied to correlate the experimental d ata.