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The present work experimentally investigated the effect of temperature change on the geometric structure of isolated mixing regions (IMRs) in a stirred vessel by the decolorization of fluorescent green dye by acid-base neutralization. A four-bladed Rushton turbine was installed in an unbaffled stirred vessel filled with glycerin as a working fluid. The temperature of working fluid was changed in a stepwise manner from 30°C to a certain fixed value by changing the temperature of the water jacket that the vessel was equipped with. The step temperature change can dramatically reduce the elimination time of IMRs, as compared with a steady temperature operation. During the transient process from an initial state to disappearance of IMR, the IMR showed interesting three-dimensional geometrical changes, that are, simple torus with single filament, simple torus without filaments, a combination of crescent shape and circular tori, and doubly entangled torus.

Gas absorption enhancement of gas-liquid slug ow by adding non-porous ne particles into the liquid phase was investigated. A glass tube with a millimeter-size diameter was used as the ow channel, and the gas and liquid slugs were air and distilled water, respectively. When the absorption rates of oxygen with and without the addition of nonporous silica ne particles in water were compared by the liquid-side mass-transfer coe cient, k L , the rate with particles was enhanced and increased as the concentration and diameter of the particles increased. This is because the frequency of particle circulation in the liquid slug increased at higher concentration, and the larger particles caused stronger disturbances at the boundary layer at the interface on the liquid-phase side.

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