The effects of surface tension on flooding in counter-current two-phase flow in an inclined tube

Abstract The purpose of the present study is to investigate the effects of surface tension on flooding phenomena in counter-current two-phase flow in an inclined tube. Previous studies by other researchers have shown that surface tension has a stabilizing effect on the falling liquid film under certain conditions and a destabilizing or unclear trend under other conditions. Experimental results are reported herein for air–water systems in which a surfactant has been added to vary the liquid surface tension without altering other liquid properties. The flooding section is a tube of 16 mm in inner diameter and 1.1 m length, inclined at 30–60° from horizontal. The flooding mechanisms were observed by using two high-speed video cameras and by measuring the time variation of liquid hold-up along the test tube. The results show that effects of surface tension are significant. The gas velocity needed to induce flooding is lower for a lower surface tension. There was no upward motion of the air–water interfacial waves upon flooding occurrence, even for lower a surface tension. Observations on the liquid film behavior after flooding occurred suggest that the entrainment of liquid droplets plays an important role in the upward transport of liquid. Finally, an empirical correlation for flooding velocities is proposed that includes functional dependencies on surface tension and tube inclination.

[1]  D. G. Kröger,et al.  The influence of fluid properties and inlet geometry on flooding in vertical and inclined tubes , 1996 .

[2]  A. E. Dukler,et al.  Countercurrent gas‐liquid annular flow, including the flooding state , 1988 .

[3]  G. Wallis.  One Dimensional Two-Phase Flow , 1969 .

[4]  Spiros V. Paras,et al.  Incipient flooding in inclined tubes of small diameter , 2003 .

[5]  Deendarlianto,et al.  The Effects of Surface Tension on the Flow Pattern and Counter-Current Flow Limitation (CCFL) in Gas-Liquid Two-Phase Flow in an Inclined Pipe , 2004 .

[6]  Yehuda Taitel,et al.  Flooding in inclined pipes — Effect of entrance section , 1986 .

[7]  Tohru Fukano.  Measurement of time varying thickness of liquid film flowing with high speed gas flow by a constant electric current method (CECM) , 1998 .

[8]  J. Oishi,et al.  Flooding in a Wetted Wall Tower , 1954 .

[9]  Experimental study of air–water countercurrent annular flow under post-flooding conditions , 2002 .

[10]  Deendarlianto,et al.  Investigation of liquid film behavior at the onset of flooding during adiabatic counter-current air–water two-phase flow in an inclined pipe , 2005 .

[11]  Colin Pritchard,et al.  EFFECT OF VISCOSITY ON FLOODING CONDITIONS IN WETTED WALL COLUMNS , 1966 .

[12]  Gian Piero Celata,et al.  Flooding in inclined pipes with obstructions , 1992 .

[13]  Tatsuhiro Ueda,et al.  Behaviour of liquid films and flooding in counter-current two-phase flow—Part 1. Flow in circular tubes , 1977 .

[14]  S. Maharudrayya,et al.  Investigation of postflooding conditions in countercurrent gas–liquid flow , 2002 .

[15]  Deendarlianto,et al.  Prediction of flooding gas velocity in gas–liquid counter-current two-phase flow in inclined pipes , 2006 .

[16]  A. E. Dukler,et al.  Flooding in vertical tubes—I. Experimental studies of the entry region , 1994 .

[17]  M. Y. Young,et al.  Flooding in the pressurizer surge line of AP600 plant and analyses of APEX data , 1999 .