HFO-1123, HFO-1234ze(E), HFC-32, surface tension, mixtures
HFOs (hydro-fluoro-olefins), HFO-1123 and HFO-1234ze(E) with GWP (global warming potential) of less than 1 attracted attention in a field of air conditioning and refrigeration engineering. However, the use of those HFO alone in such heat pump systems lucks adequate capacity or chemical stability. To compensate the shortcomings, mixtures coupled with R32 is considered to be one solution. This paper presents the surface tension measurement data of HFC-32, HFO-1123, and HFO-1234ze(E), and also their binary mixtures HFO-1123/HFC-32 and HFO-1234ze(E)/HFC-32 at various mass fractions. The capillary constant and surface tension of those are measured across temperature range from 267 K to 307 K using a measuring apparatus based on the differential capillary rise method to discuss the effects of mass fraction to the surface tension of HFO-1123/HFC-32 and HFO-1234ze(E)/HFC-32. The propagated uncertainty in the surface tension is typically 0.3 mN m-1. The experimentally quantified surface tension of HFC-32 alone well agrees with the calculated value of REFPROP ver. 9.1, and also data in literatures. However, data of HFO-1234ze(E) showed slightly negative deviation to REFPROP. To the authors’ best knowledge, available data for HFO-1123 was not found and presented data are new, so far. Among the selected predicting methods, the correlations of Di Nicola et al. (2011) and Gharagheizi et al. (2012) show the best agreement with data of two HFOs. The measured surface tension data of HFO-1123/HFC-32 at a HFC-32 mass fraction of 0.48 well agree with the correlation of Di Nicola et al. (2017). However, the correlation deviates from the present data as mass fraction approaches to 0 and 1. Similarly, data of HFO-1234ze(E)/HFC-32 shows considerable deviations.