Scale-Up Factor for Mean Drop Diameter in Batch Rotor-Stator Mixers

Abstract

The objective of this study is to propose a scale-up factor for a mean drop diameter in batch rotor.stator mixers. We define a homogenization index (H.I.) as a scale-up factor obtained from a local energy dissipation rate of turbulence and a circulation number. The local energy dissipation rate is calculated using the volume of the homogenization region, and the local power consumption is obtained from the measured net power consumption and the flow rate.We also measure the mean drop diameter using certain time interval for different configurations of mixers and different operating conditions in order to evaluate the validity of the scale-up index using H.I. Experimental results show that H.I. could well account for the mean drop diameter under different rotor speed conditions (13–27 m/s), with a different gap width between the rotor and the stator (0.15–0.25 mm) and different sizes of mixers and production volume (rotor diameters were 30 and 57 mm; production scale was 1.5 and 9 L). These results indicate that H.I. can be used to predict the mean drop diameter. Our results also suggest that the scale-up criteria for the mean drop diameter in relation to mixing time is based on H.I., and not necessarily on geometrical similarities, same rotor tip speed, or gap width in the case of similar mixer configurations and our experimental range (1 to 10 L) used for our model product, which is similar to typical dairy foods.