This paper explores the heat transfer and fluid flow characteristics of the low-GWP refrigerant R1234yf duringflow boiling inside a mini microfin tube with internal diameter at the fin tip of 4.2 mm, 40 fins, 0.15 mm high,and a helix angle of 18°. The microfin tube is brazed inside a copper plate, electrically heated from the bottom.Several T-type thermocouples are inserted in the wall to measure the temperature distribution during the phasechange process. In particular, the experimental measurements were carried out at constant mean saturationtemperature of 30 °C, by varying the refrigerant mass velocity between 200 kg m~(-2) s~(-1) and 400 kg m~(-2) s~(-1), thevapor quality from 0.2 to 0.95, at three different heat fluxes: 15, 30, and 45 kW m~(-2). The experimental resultsare presented in terms of the two-phase heat transfer coefficient, onset of dryout vapor quality, and frictionalpressure drop as a function of the operating test conditions.
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