A Numerical Study of Mixing Performance of High-Viscosity Fluid in Novel Static Mixers with Multitwisted Leaves

Abstract

The flow performance of a high-viscosity fluid in novel static mixers with multitwisted leaves was investigated numerically in the range of Re = 0.1−150. The effects of mixing-segment construction, Reynolds number, and aspect ratio on the chaotic mixing characteristics of different static mixers were evaluated based on the Lagrangian tracking method. The tracer particle distributions, G values, extensional efficiency characteristics, and stretching fields were used to evaluate the dispersion and distribution mixing performances in the new static mixers. Compared with the Kenics static mixer (KSM), the static mixers with three twisted leaves (TKSM) and four twisted leaves (FKSM) achieved chaotic mixing status much earlier and could also maintain this status by successive mixing-element groups. In contrast, there were large unmixed zones in the static mixer with double twisted leaves (DKSM). Stretching rates calculated from pathlines were found to be in good agreement with results reported in the literature. The particle trajectories revealed that the logarithm of the stretching rate increased linearly with the dimensionless axial length. For a given length of static mixer, a decrease in aspect ratio benefited an increasing stretching rate. When the number of multitwisted leaves in the cross section was greater than 2, the range of the probability density curve became larger than that of the KSM. All of the static mixers were found to have small groups of material points experiencing very high stretching. The TKSM and FKSM were found to have higher mixing efficiencies than the KSM, whereas the DKSM exhibited a worse micromixing ability.

Chaotic mixing characteristics in static mixers with different axial twisted‐tape inserts

“…Consequently, the velocity field is likely to be well‐described if pressure results are satisfactory . The numerical pressure results of CFD models predicted by Meng et al had close agreement with the data available in previous literature . In order to guarantee that the CFD model of the Kenics static mixer correctly predicted its mixing behaviour over a broad range of laminar conditions, the model was also validated by comparing the predicted numerical residence time distribution (RTD) to experimental results in the literature, as shown in Figure b.…”

Improving mixing performance by curved‐blade static mixer

“…A quantitative comparison of industrial static mixers based on their performance revealed that open mixers compared with compact mixers require lower pressure drop to drive the flow, but at the expense of increasing mixing length 3 . Design modifications have also been performed to obtain usually a better and faster mixing 4‐7 . For example, Liu et al 5 used a frame‐indifferent parameter to classify the flow types in the SMX mixer and concluded that using a mixing element with 10 crossbars followed by the standard SMX mixer with eight crossbars gives the best mixing quality.…”

Numerical Investigation of the Performance of Kenics Static Mixers for the Agitation of Shear Thinning Fluids

“…The mixing is ensured by stretching and reorientation of fluid during its passage through the blade: the twist and perpendicular cut delivers a sequence of folding and stacking (Rafiee et al, 2013). Meng et al (2014) studied numerically the mixing performance of static mixers with multi-twisted leaves like Kenics mixer. Meijer et al (2012) achieved a quantitative comparison of static mixers.…”