A Methodical Approach to Scaling Up an Aerated Coaxial Mixer Containing a Shear-Thinning Fluid: Effect of the Fluid Rheology

Abstract

The evolution of the rheological behavior of the fluid is one of the primary challenges encountered in the scale-up of the most aerated reactors. In fact, mixing efficiency diminishes because of the changes in the fluid rheological properties. Under these circumstances, it is challenging to keep the mass transfer constant upon scale-up. A thorough literature review revealed that no scale-up study of aerated coaxial mixers has considered the effect of varying fluid rheological properties. Therefore, to analyze the scale-up of these aerated mixing systems, the effects of the impeller speed and type, fluid rheology, and aeration rate on the gas hold-up, local mass transfer coefficient, bubble size distribution, hydrodynamics, and specific power consumption were explored. Electrical resistant tomography, dynamic gassing-in, and computational fluid dynamics methods were employed. For the first time, a systematic approach based on a constant volumetric mass transfer has been proposed for the scale-up of aerated coaxial reactors at different fluid rheological properties.