Effect of inlet conditions on taylor bubble length in microchannels

Abstract

The effect of inlet conditions on the frequency and size of the bubbles that form during gas-liquid Taylor flow in microchannels is investigated in this paper. Three different inlet configurations, T-, Y- and Mjunction as well as three test channels with hydraulic diameters 0.345mm, 0.577mm and 0.816mm were used. The test fluids were nitrogen and water or octane, that have different surface tension. It was found that bubble length increased with increasing gas flowrate, gas inlet size and liquid surface tension and decreasing liquid flowrate. From the different inlet configurations, the M-junction resulted in the largest bubbles and the Y-junction in the smallest ones particularly at low liquid flowrates. The experimental bubble sizes were tested against a number of literature correlations but the agreement was not very good. Two new correlations were developed for the T- and the Y-junctions to calculate the unit cell (one bubble and one slug) frequency from which the bubble length can be found. Bubble lengths predicted from these correlations were in good agreement with experimental ones obtained from video recordings.