The liquid viscosity of six binary mixtures of HFC-134a with glycols l-ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol(400), and polypropylene glycol (2000)] was measured in the temperature range from 273 to 333 K. The viscosity was measured with an improved capillary viscometer instead of the rolling-ball viscometer reported in our previous work. The measurement uncertainty was estimated to be 1.6%. Most of the present data are higher than previous data, and the gap between the two sets of data increases further in low-viscosity regions. The present results obtained with laminar flow are more reliable than previous results, which are indefinite because of the limit of usefulness of the rolling-ball viscometer in low-viscosity regions.

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