Experimental Study of Single and Two-Phase Flow and Heat Transfer Characteristics in Helical Tube under Motion Condition

The unique structural characteristic of the helical coiled pipe causes some special phenomena such as the secondary flow effect inside the tube, and the heat transfer characteristics are more complicated than those in circular pipe. There have been few published papers about experimental research of flow and heat transfer characteristics of helical tube under motion conditions. An experimental loop was built based on the background above. An experimental study of single-phase and saturated boiling two-phase heat transfer characteristics and flow instability in helical tubes under multiple motion conditions was carried out. In which the maximum system pressure was 4 MPa, mass flux was 550 kg/(m2<middle dot>s), and heat flux of the test section was 360 kW/m2. The results show that the heat transfer capacity of the side close to the central axis of the helical tube is significantly lower than that of the side away from the central axis under rocking and inclination conditions. An empirical correlation of the heat transfer coefficient in helical tube under static and motion conditions was drafted based on the experiment data of single-phase conditions. The influence of motion conditions on two-phase heat transfer characteristics was similar to that of a single phase but much weaker.