High shear impellers (HSIs) are mixers used in industrial stirred tanks to incorporate powders into liquid and break down particle agglomerates. In this work, a detail numerical study of two commercial ring-style HSIs of laboratory scale (Hockmeyer® Equipment Corp. D-Blade of two and four rings) was carried out at 50≤ Re ≤75, and their performance was compared with the Rushton Turbine (RT). It was found that power and pumping numbers or their ratio, cannot be simply connected for selecting properly an impeller in applications where highly localized viscous dissipation is desirable. The ratio of the average viscous dissipation in the impeller swept volume, , to the mean in the entire volume, , at two constant values of power input, P , was found to be lower for HSIs to that evaluated for RT. However, when P increases from 4.25 to 12.92 W , the dimensionless average viscous dissipation in the blade swept volume, at the higher P was found to be similar for the HSI of two rings and the RT, corroborating the high local viscous dissipation of this HSI when operated at higher speeds.
Chemistry and Pharmacology
Process Engineering, Biotechnology, Nutrition Technology