Experimental study on condensation of a zeotropic mixture R1234ze(E) / R32 in a horizontal micro-fin tube

Heat transfer and pressure drop during condensation of a zeotropic refrigerant mixture R1234ze(E)/R32 (50/50 mass%) and pure refrigerants R1234ze(E) and R32 in a horizontal micro-fin tube are experimentally investigated in this paper. Experiments are conducted in the mass velocity range of 150 to 400 kg m^-2s^-1 at a constant inlet temperature 40°C. Tested micro-fin tube is made of copper, and its geometry is as follows: 6.05 mm in outer diameter, 5.21 mm in mean inside diameter, 0.26 mm in fin height, and 20 degree in spiral angle. The effects of mass velocity and the difference of pure and mixed refrigerants on heat transfer and frictional pressure drop characteristics are clarified. The measured heat transfer coefficient and frictional pressure drop of the zeotropic mixture are compared with several existing correlations.