A model on water level dynamics in natural circulation drum-type boilers

This paper investigates the countercurrent gas–liquid flow in an annular gap bubble column with a 0.24 m inner diameter by using experimental and numerical investigations. The two-phase flow is studied experimentally using flow visualizations, gas holdup measurements, and double fiber optical probes in the following range of operating conditions: superficial air velocities up to 0.23 m/s and superficial water velocities up to −0.11 m/s, corresponding to gas holdups up to 29%. The flow visualizations were used to observe the flow patterns and to obtain the bubble size distribution (BSD). The gas holdup measurements were used for investigating the flow regime transitions, and the double fiber optical probes were used to study the local flow phenomena. A computational fluid dynamics (CFD) Eulerian two-fluid modeling of the column operating in the bubbly flow regime is proposed using the commercial software ansys fluent. The three-dimensional (3D) transient simulations have been performed considering a set of nondrag forces and polydispersity. It is shown that the errors in the global holdup and in the local properties are below 7% and 16%, respectively, in the range considered.

Annular Gap Bubble Column: Experimental Investigation and Computational Fluid Dynamics Modeling

Tomographic imaging of counter-current bubbly flow by wire mesh tomography

Resultats d'une etude experimentale et theorique du comportement d'un ecoulement biphase huile/eau dans des conduits verticaux. L'ecoulement bulle est predominant bien que si la vitesse augmente il devienne de type bouchon. La methode proposee, developpee a partir du principe de derive de flux, s'appuie sur des donnees experimentales et bibliographiques, ses avantages par rapport aux autres methodes sont discutees.

S. Srinivasan

Papers

Countercurrent bubble and slug flows in a vertical system