Measurements of the surface tension for the R290 + R32 mixture

There were no data of the surface tension for the R290 + R32 mixture which is expected as one of the new refrigerant mixtures, and its prediction is considered to be difficult because it is a mixture of a very polar molecule with a nonpolar molecule. In this work, the surface tension measurements for the R290 + R32 mixture were carried out by the differential capillary-rise method modified for measuring mixtures. Thirtyone, thirty-five, and thirty-three data points were obtained with changing the composition of the mixture at T = 280 K, 290 K, and 300 K, respectively. The experimental uncertainties of temperature and surface tension are estimated to be within 20 mK and 0.2 mN·m ^-1, respectively. The excess molar surface tension is also calculated by the present data, and its uncertainty was estimated to be 0.3 mN·m^-1. The excess molar surface tension was correlated as a function of composition. The deviation of the present data from the present correlation was within the experimental uncertainty.