Measurements of the Liquid Viscosities of Mixtures of Isobutane with Squalane to 30 MPa

The viscosities of liquidmixtures of isobutane with squalane, which seem to be representative of mixtures of refrigerants with refrigeration oil, were measured from 273.15 to 333.15K at pressures to 30MPa using a falling-body viscometer. The uncertainty of the measurements was estimated to be no larger than 2.9%. The experimental viscosity values were fitted with a Tait-like equation within 2.8%. There are large deviations between the experimental data and calculated values predicted by the equation of Kanti et al., which is derived from Flory’s theory. By introducing two index numbers of the energetic mixing rule into the equation, the predictions could be improved considerably.