Thermophysical Properties of the Refrigerant Mixtures R417A and R417B from Dynamic Light Scattering (DLS)

Dynamic light scattering (DLS) has been used for the measurement of several thermophysical properties of the refrigerant mixtures R417A (50 % by mass 1,1,1,2-tetrafluoroethane—R134a, 46.6 % pentafluoroethane—R125, 3.4 % n-butane—R600) and R417B (79 % by mass R125, 18.25 % R134a, 2.75 % R600). Both refrigerant mixtures are designed for a replacement of R22 (chlorodifluoromethane) in existing refrigeration systems. Thermal diffusivity and sound speed have been obtained by light scattering from the bulk fluid for the liquid phase under saturation conditions over a temperature range from about 283 K up to the liquid–vapor critical point with estimated uncertainties between 1 % and 3 % and between 0.5 % and 2 %, respectively. By applying the method of DLS to a liquid–vapor interface, also called surface light scattering, the saturated liquid kinematic viscosity and surface tension have been determined simultaneously. These properties have been measured from 253.15 K up to the liquid–vapor critical point with estimated uncertainties between 1 % and 3 % for kinematic viscosity and between 1 % and 2 % for surface tension. The measured thermal diffusivity, sound speed, kinematic viscosity, and surface tension are represented by interpolating expressions with differences between the experimental and calculated values that are comparable with but always smaller than the uncertainties. The results are discussed in detail in comparison with literature data and with various prediction methods.