Saturated liquid viscosity and surface tension of alternative refrigerants

Light scattering by thermally excited capillary waves on liquid surfaces or interfaces can be used For the investigation of viscoelastic properties of fluids. In this work, we carried nut the simultaneous determination of the surface tension and the liquid kinematic viscosity of some alternative ref rigerants by surface light scattering (SLS) on a gas-liquid interface. The experiments are based on a hetero dyne detection scheme and signal analysis by photon correlation spectroscopy (PCS). R23 (trifluoromethane), R32 (dif luoromethane), R125 (pentafluoroethane). R143a (1,1,1-trifluoroethane), R13 4a (1,1,1,2-tetrafluoroethane); R152a (1,1-difluoroethane), and R123 (2,2-d ichloro-1,1,1-trifluoroethane) were investigated under saturation condition s over a wide temperature range, from 233 K up to the critical point. It is estimated that the uncertainty of the present sur-Face tension data for th e whole temperature range is less than +/-0.2 mN(.)m(-1). For temperatures up to about 0.95T(c). the kinematic viscosity of the liquid phase could be obtained with an absolute accuracy of better than 2%. For the highest tempe ratures studied in this work, measurements for the kinematic viscosity exhi bit a maximum uncertainty of about +/-4%. Viscosity and surface tension dat a are represented by a. polynomial function of temperature and by a van der Waals-type sui face tension equation, respectively. The results are discus sed in detail with comparison to literature data.