EXPERIMENTAL INVESTIGATION OF CONDENSATION HEAT TRANSFER AND PRESSURE DROP OF R152a/R1234ze(E) IN A SMOOTH HORIZONTAL TUBE

The heat transfer and pressure drop performances of R152a/R1234ze(E) by mass fraction of 0.6/0.4 are studied experimentally. Experiments are carried out at mass flux between 173 to 462 kg·m-2·s-1, heat flux between 5 to 10 kW·m-2, saturation temperature between 30 to 40°C, and mean vapor quality between 0.16 to 0.93 in a smooth horizontal tube with an inner diameter of 4.0 mm. The effects of heat flux, refrigerant mass flux, saturation temperature, and vapor quality on heat transfer coefficient and frictional pressure gradient are analyzed. The heat transfer coefficient increases with mass flux and vapor quality and decreases with saturation temperature, showing great sensitivity to heat flux. The frictional pressure gradient increases with mass flux and vapor quality and decreases with saturation temperature, while the heat flux has a little effect on the frictional pressure gradient. Furthermore, the studied models predict the experimental condensation heat transfer coefficient poorly, and a new model is proposed, which offers a satisfactory accuracy with an absolute deviation of 13.08%. The Muller-Steinhagen and Heck correlation shows acceptable agreement with the experimental frictional pressure gradient with the lowest absolute deviation of 9.37%.