Effect of tube diameter on flooding

This paper describes an experimental study on the effect of tube diameter o n the mechanism of flooding in vertical gas-liquid countercurrent annular f low. Flooding experiments were conducted with three different tube inner di ameters, namely, 25, 67 and 99 mm with smooth inlet and outlet conditions f or air and water. The results indicate that the mechanism of flooding is qu alitatively different in the small and the large diameter test sections. Wh ile flooding in the 25 mm diameter section occurred essentially by the upwa rd movement of large waves created near the liquid outlet. no such waves co uld be seen in the 67 and the 99 nlm diameter test sections. Here, flooding occurred by droplet carryover or by an unstable, churn-like motion in the liquid him. The results are compared with existing correlations. The effect of test section length on flooding was also investigated. (C) 2001 Elsevie r Science Ltd. All rights reserved.