Comprehensive study of regime transitions throughout a bubble column using resistivity probe

Flow regime transitions were experimentally characterized using several local bubble properties measured by a double-needle resistivity probe. Experiments were carried out in a bubble column of 0.09 m diameter and 1.8 m height. The superficial gas velocity was changed from 0.005 to 0.070 m/s and the superficial liquid velocity from 0.003 to 0.060 m/s. Average bubble chord length, bubble frequency and sauter mean bubble chord length were obtained at various locations of the column by placing the probe at three axial and six radial positions. Transitions between dispersed bubble flow, discrete bubble flow, coalesced bubble flow and slug flow were detected at these locations. A comparison between transition points at different locations verified that regime transition occurs throughout the bubble column at nearly the same superficial gas and liquid velocities. A flow regime map was also obtained based on the local measurements of the bubble properties at different locations.

► Flow regime transitions were determined in a bubble column by employing a double-needle resistivity probe.
► The resistivity probe method is applicable to detect transition between discrete bubble and coalesced bubble flows.
► It is necessary to place the probe far from the distributer and column wall to be able to determine the onset of the slug flow.
► A flow regime map was presented based on the measured data.