Surface tension measurement of low gwp refrigerants.

HFOs (hydro-fluoro-olefins) are very recently under consideration as a potential candidate of R410A alternatives with GWP of 2800 that is most widely used in air-conditioning and refrigeration systems. The capillary constant and surface tension of R32, R1234ze(E), and their binary mixture R32/R1234ze(E) are measured in the temperature range from 274 K to 342 K by the differential capillary rise method. The propagated uncertainty in the surface tension is estimated within 0.3 mN m-1. The experimentally quantified surface tensions of the components R32 and R1234ze(E) well agree with the calculated value by REFPROP 9.1. The measured surface tension of R32/R1234ze(E) at charged compositions 51/49 mass% and 43/57 mass% reasonably agree with the correlation for R32/R1234ze(E) (50/50 mass%) proposed by Tanaka and Higashi [1]. The surface tension data presented in this study and available in literatures (Tanaka and Higashi [1]; Cui et al. [2]) appear to vary almost linearly against mole fraction at a fixed reduced temperature.