Viscosity measurement of low GWP refrigerants with a tandem capillary tubes method.

New experimental data on the viscosity of low-GWP refrigerants such as HFOs are reported in order to contribute for development of low-GWP refrigeration/heat pump systems. Accurate data of thermodynamic and transport properties are indispensable to design and to manufacture the systems with high efficiency. However, there are only limited data of the viscosity. In this study, the viscosity of low-GWP refrigerants were measured by a tandem capillary tubes method with wide temperature and pressure range covered from subcooled liquid to superheated vapor region. In this method, the test fluid flows inside two different length and same diameter capillary tubes connected in series in order to eliminate the pressure drop at the inlet and outlet therefore the measurements have better accuracy than the single capillary tube method. Because correlations to calculate the viscosity at arbitrary conditions are useful for investigations, designs and simulations, correlations which can be available in wide temperature and pressure range are also proposed in the present study. The correlations developed are based on Extended Corresponding States (ECS) model.