ISSN Online: 2377-424X
ISBN Print: 978-1-56700-421-2
International Heat Transfer Conference 15
Population Balance Modeling of Air-Water Bubbly Flow in a Vertical U-Bend
Sinopsis
Bubbly flow in U-bend is widely encountered in two phase flow systems because of its compactness and high
heat transfer coefficient. The modeling of phase distributions, velocity fields and interfacial area concentration in the U-bend is crucial for the analysis of mass, momentum and energy transportation processes in the equipment. However, this subject has not received enough attention yet. In this paper, the combination of population balance model and two-fluid model was used in the simulation of air-water bubbly flow in a U-bend with 24mm inner diameter and 96mm curvature. The homogeneous MUSIG (multiple size groups) model was used to solve the
population balance equation and reconstruct the bubble size distribution (BSD) function. The phase distribution
at 0°, 90° and 180° were predicted and the results showed that the superficial velocities of gas and liquid phase were the control parameters. Under higher gas superficial velocity, the buoyant force is dominant and makes the bubbles concentrate on the outer side of the tube wall; while under lower gas superficial velocity; the centrifugal force is dominant and makes the bubbles concentrate on the inner side of the tube wall. These results met well with the experimental results of Usui. Furthermore, the relative velocity between the phases and interface area concentration were investigated under different flow conditions.
PALABRAS CLAVE:
Two-phase/Multiphase flow, Computational methods, bubbly flow, population balance model, U-bend