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International Journal of Chemical Engineering
Volume 2012, Article ID 287051, 6 pages
Research Article

Effect of Temperature Change on Geometric Structure of Isolated Mixing Regions in Stirred Vessel

Department of Chemical Science and Engineering, Kobe University, 1-1 Rokkodai, Nada, Hyogo, Kobe 657-8501, Japan

Received 11 February 2012; Accepted 5 April 2012

Academic Editor: See-Jo Kim

Copyright © 2012 Nor Hanizah Shahirudin et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


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.