DISENGAGEMENT ENERGETICS AT THE SURFACE OF AERATED REACTORS

Aerated reactors are widely used in cell culture processes. The bubbles that are introduced into such reactors provide essential mixing and oxygen, but the disengagement of those bubbles can result in the imposition of undesirable stresses upon fluid-borne cells. This occurs because some of the energy associated with interfacial tension is converted to high-velocity motions in the form of film rupture, droplet ejection and bubble cavity collapse. Obviously these effects would be amplified if there was an affinity between the cells and the gas-liquid interface. The present work was carried out in an effort to better characterize the energy, frequency of occurrence, and periodicities of these phenomena. This investigation examined the effects of fluid (medium) properties, bubble size, and gas rate upon both film and jet droplet ejection processes, as well as upon pressure disturbances measured at the reactor wall just beneath the free surface