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ISSN Online: 2377-424X

ISBN Print: 0-89116-130-9

International Heat Transfer Conference 6
August, 7-11, 1978, Toronto, Canada

MECHANISM AND CORRELATION OF POWER DISSIPATION IN LIQUID-GAS MIXING IN A PERFORATED-DISK TYPE STIRRING CASCADE

Get access (open in a dialog) DOI: 10.1615/IHTC6.3950
pages 7-12

Resumo

The explanation is given for the physical causes of the large power reduction that is associated with the presence of the gaseous phase in a three-stage perforated-disk type stirring cascade. Test data obtained using water and water-methanol mixture as the continuous phases and air as the dispersed phase are correlated. It is disclosed that the characteristic power curves are analogous to the torque coefficient curves of a rotating disk in axial flow: with an increase in the impeller Reynolds number, the power number decreases linearly in the laminar flow regime followed by an increase in the transition region and then becomes essentially constant in the turbulent regime. An expression is derived to predict the critical impeller Reynolds number for effective gas dispersion below which operation of the agitator becomes impractical. The phenomenon of "flooding of the impeller" is explained and its range defined. Some design guidelines are recommended based on the power performance characteristics.