Flow Boiling Heat Transfer and Pressure Drop of R1234ze(E) and R32 in a Horizontal Micro-Fin Tube

In the present study, the flow boiling heat transfer of R1234ze(E), R32 and zeotropic mixture R1234ze(E)/R32 (50/50 mass%) in a horizontal micro-fin tube is experimentally investigated to clarify the pressure drop and heat transfer characteristics. Tested micro-fin tube is made of copper, and its geometry is as follows, 6.00 mm in outer diameter, 5.21 mm in mean inside diameter, 0.26 mm in fin height and 20 degree in spiral angle. Experiments are conducted in the mass velocity range of 150 to 400 kg m-2s-1 at a constant inlet temperature 10 oC. The effects of mass velocity and the difference of refrigerants on heat transfer and frictional pressure drop characteristics are clarified. The measured pressure drop and heat transfer characteristics of pure refrigerants are also compared with some correlations.