Research :: Rising Bubbles in Liquid Columns
Chaos in Bubble Columns (Last updated 2004)

Over the last five years I have been active in the bubble column experiments that explore the effect of external electric fields on the bubbling characteristics. Our research has shown that the bubble formation becomes increasingly nonlinear and chaotic with increasing gas flow rate and electrostatic potential. The effect of the latter is very sensitive to the capillary or nozzle used, which gives us a new manipulated variable to control bubbling, interfacial surface area and transfer rates. The research has important implications for many chemical processes such as distillation and gas absorption/stripping to name a few. At present, I am involved in implementing OGY control on a bubble column using the electrostatic potential as the manipulating variable. See Publications page for more information.

The most recent findings for bubble formation under external electrostatic fields are reported in paper 335c. Presented at the 2003 AIChE Annual meeting at Chemical Engineering Science by considering larger electrostatic fields and several different nozzle diameters and geometries. Chem. Eng. Sci. is one of the top-ten journals in Chemical Engineering as measured by the impact factor.

Complexity of Bubble Formation (Last updated 2004)

Bubble formation under external electrostatic fields is very complex. In fact, sometimes we observed that the bubbling characteristics changed while the operating conditions remain unchanged. An early report of this and a test for this apparent nonstationarity was presented at paper 268e at the 2001 AIChE Annual meeting in Reno, NV. See slides of the presentation. At present we are working on a more sophisticated technique to identify the nonstationarity of the column.

We have found that using the CLPC algorithm on return maps or 3-D embeddings seems to work well with the bubble column data, but at low gas flow rates, the behavior is too complex to be modeled due to various physical phenomena coming into play.