The effect of scale on the breakup process in liquid-liquid agitated tanks was investigated. Transient drop size distributions in the breakup process were measured in geometrically similar mixing vessels at equal power input per unit mass, which was taken as a scale-up criterion under the assumption of isotropic turbulence for the flow around drops. The distributions in each vessel, however, did not undergo the same variation with time and the condition of equal power input per unit mass was found to be inappropriate as a scale-up criterion for the breakup process. The experimental result was explained from direct observation of breakups in the mixing vessels by high-speed cine-photography. The observations made it clear that breakups occurred not only in the isotropic turbulent region but also in the nonisotropic turbulent region. A new model for the breakup process was proposed which considers breakups in both regions. This model successfully predicted the transient drop size distributions.
ASJC Scopus subject areas
- Chemical Engineering(all)