Coaxial mixers are known to be well adapted to mixing situations characterized by complex rheological behavior and viscosity evolution to name a few. A new coaxial mixer has been introduced by SHI Mechanical & Equipment, known as Superblend, which combines a MaxblendŽ impeller and a helical ribbon. The aim of this work was to experimentally investigate the performance of the Superblend, focusing on rotating modes (co- and counter-rotating) in the laminar, transition and turbulent flow regimes, and also to compare its performance with previously studied dual shaft coaxial mixers. In order to achieve the objective, a fully instrumented Superblend (40 L) was used, consisting of a MaxblendŽ impeller and a helical ribbon mounted on two independently actuated coaxial shafts running respectively at high and low speed and operating either in co-rotating or counter-rotating mode. Power consumption and mixing time experiments using the discoloration technique were conducted using aqueous solutions of corn syrup and water as Newtonian fluid. Based on mixing efficiency criteria, this study confirmed that the co-rotating mode is consistently yielding the best results in the laminar and early transition regimes. Recent power correlations introduced by our group for coaxial mixers were tested for their applicability and they were proven to be very applicable for the Superblend. This work demonstrates the efficiency of the Superblend and its superiority when compared to the dual shaft coaxial mixers based on different mixing efficiency criteria.

Keywords: Superblend, Maxblend, Helical Ribbon, Newtonian fluid, Laminar, Turbulent, Power consumption, Mixing time.