Power requirement for mixing shear-thinning fluids with a planetary mixer
Résumé
The optimal control of processes dealing with non-Newtonian liquids requires the knowledge and control of the power demand of the mixing equipment. In this context, an extension of the Metzner and Otto concept to planetary mixers is proposed to adapt this concept to planetary mixers. The theoretical part of this work defines modified expressions of Reynolds and power numbers. These definitions introduce a characteristic velocity u(ch) that is used to define the parameter K-s. A planetary mixer is employed to experimentally ascertain this guideline. Power consumption measurements carried out by mixing shear-thinning fluids permit to determine the Ks factor. This factor varies only slightly with the flow behavior index and may be regarded as a defined constant for this geometry. Finally, experiments with an additional shear-thickening fluid confirm the validity of this approach.