Experimental study of air–steam condensation on the influence of tube diameter and inclination angle.

• The experimental pressure range (0.15 ~ 1.6 MPa) and subcooling range (28 ~ 122 °C) are relatively large. • The effect of tube diameter and inclination angle on the condensation with non-condensable gases was analyzed. • An experimental correlation containing the effect of tube diameter and inclination angle was obtained. Steam-air condensation is one of the important physical phenomena after reactor accidents, which has direct impacts on the discharge of containment residual heat after the accident. Previously, many researchers have proposed experimental correlations for condensation of non-condensable gas, which include the influence of pressure, concentration, and wall subcooling. However, there are relatively few studies on the influence of tube diameter and inclination angle. In order to investigate the heat transfer characteristics of the condenser at different tube diameters (19 mm, 15 mm, 12 mm) and inclination angles (0 ~ 90°), experiments were carried out in the pressure range of 0.15 ~ 1.6 MPa, air mass fraction of 14 ~ 87%, and wall subcooling of 28 ~ 122 °C. It shows that the condensation heat transfer coefficient (HTC) increases with the decrease of the tube diameter and inclination angle. The condensation HTC with a tube diameter of 12 mm and an inclination angle of 0°(Horizontally) is around 32 ~ 38% larger than that of the heat transfer tube with a tube diameter of 19 mm and an inclination angle of 90°(Vertically). Based on a total of 2276 data points from the present work and related experiments, an experimental correlation containing the effect of tube diameter and inclination angle is proposed, and its deviation is within ± 15% with 95% confidence. [ABSTRACT FROM AUTHOR]