Mixing Times in Coaxial Mixers with Newtonian and Non-Newtonian Fluids

Mixing time experiments were performed using a coaxial mixing system consisting of an anchor impeller and three different types of impellers, namely a Rushton turbine, a Rayneri-Sevin impeller, and a new hybrid dispersing impeller. Both co- and counterrotating modes were investigated with Newtonian and shear-thinning fluids. It was found that mixing times were significantly reduced in corotating mode compared to the counterrotating mode or with the only impeller rotating at the same power per unit volume in the transition regimes. Among the various turbine impellers considered, the Rushton turbine was found to be the most effective one in terms of homogenization with Newtonian and non-Newtonian fluids.