(565g) Hydrodynamics and Mixing Characterization in a High Shear Mixer

High shear mixers (HSMs) are widely used in process industries (e.g. food industry, paint industry, pharmaceuticals, etc.) for carrying out reactive mixing and dispersed phase size reduction. HSMs are also knows as rotor-stator-mixers and are characterized by their highly localized energy dissipation and drop size distributions. In the present work the computational fluid dynamic modeling of an existing HSM and a proposed novel HSM design is carried out using k-ε turbulence model. The existing HSM considered in the present work is comprised of square holes in the stator and a rotor with 4 blades. The proposed mixer design is comprised of tilted jets/holes in the stator, for the deep penetration in the mixing vessel. The mixing characteristics and flow patterns in both mixers are analyzed in the bulk, stator and rotor regions. The results are also reported in terms of energy dissipation and power number, as both are characteristic parameters for motor selection in the mixer design, optimization and scale-up. The simulations are carried out using transient sliding mesh with k-ε  turbulence model at different rotor speeds (2000 rpm, 4000 rpm and 6000 rpm). The simulated results for power number and flow rate are compared with the existing data available in the literature and showed a variation of 8.3% and 0.8%, respectively. The proposed novel mixer has a very high efficiency as compared to the existing mixer. The mixing behavior has also been studied at different rotor speeds. Higher and uniform mixing is obtained in the proposed mixer as compared to the existing rotor stator mixer.