Bubble Coalescence, Growth, Breakup and Distribution in Boiling Water-Cooled Packed Bed Reactor

The flow patterns in the heated packed bed are different to those without the heated packed bed. To gain a deeper understanding of these phenomena, the bubble coalescence, breakup, and distribution in a volumetrically heated packed bed are determined through experiments, and are very important for recognizing the flow pattern transition mechanisms in boiling water-cooled packed bed reactors. A highspeed camera was used for capturing images of these bubbles to analyze their behavior. The results revealed five types of bubble coalescence are observed in our experimental study. Bubble growth plays an important role in the flow pattern transition because it enlarges the contact area between the bubbles and the particles in the heated packed bed. The portion of small bubbles significantly increased with the decrease of the inlet fluid temperature and the increase of mass flux. (C) 2020 Elsevier Ltd. All rights reserved.