Characteristics of flow fields in the gas-liquid mini-bubble columns
with PIV measurements
Abstract
As a new type of gas-liquid microreactors, the gas-liquid mini-bubble
column have potential applications. However, few studies on the flow
fields in the mini-bubble column can be found at present. In this work,
Particle Image Velocimetry (PIV) was first used to visually study the
velocity fields, vorticity fields and bubble dynamics in the gas-liquid
mini-bubble columns with column inner diameters of 1to 3 mm and
mini-bubble diameters ranged from 0.7 to 1.3 mm. It is found that with
the increase of superficial liquid velocity, bubbles rose from almost
straight line to Z-shaped or S-shaped trajectory, and the bubble
trajectory changed from 1-D to 3-D; when the bubble velocity changed,
the bubble size and gas holdup decreased; bubble terminal velocity was
controlled by bubble buoyancy and flow resistance, and increased
slightly with bubble coalescence. These findings may provide basic
reference for the design and scale-up of such mini-bubble column
reactor.