Power Characteristics in Coaxial Mixing:  Newtonian and Non-Newtonian Fluids

The power consumption of a coaxial mixer consisting of a wall-scraping anchor and different dispersion impellers (radial discharge) operating in co- and counterrotating modes has been experimentally characterized in the case of viscous Newtonian and non-Newtonian fluids. It was found that the anchor speed did not affect the power consumption of the dispersion turbines. The power consumption of the anchor was found to increase when the dispersion impellers were used in counterrotating mode and to decrease when they were used in corotating mode. Following the Metzner and Otto approach [AIChE J. 1957, 3 (1), 3−10], new correlations based on the impeller geometry for the generalized Reynolds number and the power number are proposed, and it is shown that a power master curve can be generated for speed ratios larger than 10.