Experimental Research on the Effects of Tube Diameter and Inclination on Steam-Air Condensation Characteristics

For light water reactor nuclear power plants, in loss of coolant accidents, large amounts of high-temperature and high-pressure steam are released into the containment. Steam condensation consisting of air is one of the important thermal-hydraulic phenomena in containment. Previous studies have proposed several experimental correlations, which include the influence of thermal parameters such as pressure, concentration, wall subcooling on condensation heat transfer coefficient. However, there is still a lack of research on the influence of geometric parameters such as pipe diameter and dip angle on condensation heat transfer coefficient. Therefore, in this study, the heat transfer characteristics of steam condensation containing non-condensing gas were tested under different pipe diameters and inclinations at pressures of 0.15~1.6 MPa and subcooling of 30~120℃. The heat transfer characteristics of three different pipe diameters (19 mm, 15 mm, 12 mm) and five different inclinations (0°, 30°, 45°, 60°, 90°) were analyzed. The results show that the condensation heat transfer coefficient increases with the decrease of pipe diameter and dip Angle. Based on 2276 experimental data points in this study and relevant domestic and international experiments, an experimental correlation including pipe diameter and inclination Angle is proposed, and its deviation is within ±15% with 95% confidence. © 2021, Science Press. All right reserved.