R1234ze(E) flow boiling heat transfer and pressure drop inside a 2.4 mm microfin tube.

There are two possible viable factors to cope with the new environmental regulations: more efficient heat exchangers and environmental-friendly refrigerants. This paper explores the use of the new low-GWP refrigerant R1234ze(E) during flow boiling inside a mini microfin tube, which has an inner diameter at the fin tip of 2.4 mm, thus it is a downsizing of the traditional microfin tubes. In the experimental tests, the mass flux was varied between 375 and 940 kg m-2 s-1, the heat flux from 10 to 50 kW m-2, and the vapour quality from 0.1 to 1. The saturation temperature at the inlet of the test section was kept constant and equal to 30°C. The results show the promising capabilities of both the mini microfin tube and the new low-GWP refrigerant, which can be used as an efficient alternative to the more common R134a.