R1234ze(E) flow boiling inside a 3.4 mm ID microfin tube

•The flow boiling heat transfer of a new low-GWP refrigerant is studied.•A new mini microfin tube is tested as enhanced solution for vaporization.•The vapour quality at the onset of the dryout is experimentally estimated.•The results for R1234ze(E) are compared against those for R134a.•Two new models are proposed and validated against R1234ze(E) data.

R1234ze(E) has a GWP<1 and a normal boiling temperature approximately 7.3 °C lower than that of R134a; it represents an interesting candidate for its replacement as working fluid in refrigerating machines. The refrigerant charge minimization in refrigerating and air conditioning equipment is a key issue for the new environmental challenges. Mini microfin tubes represent an optimal solution for both heat transfer enhancement and charge minimization tasks. This paper presents an experimental study of R1234ze(E) flow boiling inside a mini microfin tube with internal diameter at the fin tip of 3.4 mm. The experimental measurements were carried out at constant saturation temperature of 30 °C, by varying the refrigerant mass velocity between 190 kg m−2 s−1 and 940 kg m−2 s−1, the vapour quality from 0.2 to 0.99 at three different heat fluxes: 10, 25, and 50 kW m−2. The experimental results are then compared with those obtained for the more traditional R134a.