Surface tension of the binary refrigerant mixture HFC-32 + HFC-125

The surface tension of the binary mixture HFC-32+HFC-125 was measured at three nominal mass fractions of 24.95%/75.05%, 44.83%/55.17% and 66.75%/33.25% over the temperature range from 253 to 333 K using the differential capillary rise method under vapor–liquid equilibrium conditions. The temperature and surface tension uncertainties were estimated to be within ±10 mK and ±0.15 mN m−1, respectively. Correlations for pure HFC-32 and HFC-125 were used to develop a van der Waals-type correlation for the experimental data of the HFC-32+HFC-125 mixtures as a function of the mass fraction.