Mixing performance in Split-And-Recombine Milli-Static Mixers—A numerical analysis

Abstract

Very low Reynolds number laminar flow in Split-And-Recombine (SAR) static mixers is numerically investigated by using a finite volume method. In these configurations, advective chaotic flow structures are created by the passive control of the flow, mimicking the baker's transformation, through a series of flow splitting, rotations, and re-combinations that generate intertwined lamellar structures. This process leads to extra surface creation, which ultimately intensifies mass transfer. The main aim of this study is firstly to demonstrate the interest of this technique for enhancing mixing, while keeping pressure drops moderate, and secondly to optimize this type of geometry. For the latter stake, two different SARs, namely SAR1 (Gray's configuration) and SAR2 (Chen's configuration), are compared in terms of distributive and dispersive mixing and energy expenditures evaluated by the pressure drop.

A millisecond passive micromixer with low flow rate, low sample consumption and easy fabrication

“…For a split-and-recombine (SAR) mixer based on a “multi-lamination” mechanism, the main problem is often related to implementing multiple inlet channels, rotation effects or a splitting-recombination strategy, which typically adds to the complexity and expense of the design 34 , 58 . A strategic improvement would be Baker’s transformation mechanism 59 , by introducing an intricate 3D structure to split the flow, then rotate and change the direction of the flows before recombining/folding them 60 , 61 . The purpose is always the same: generating an intertwined lamellar structure.…”

Horseshoe lamination mixer (HLM) sets new standards in the production of monodisperse lipid nanoparticles

“…Mixing of fluids is assumed to be an isothermal process which is analyzed by determining the solute concentration c in the system based on the convection–diffusion eqn (2.3). 55 u⃑ ·∇ c = D ∇ 2 c where D is the molecular diffusion coefficient. The working fluids are water and ethanol with a diffusion coefficient of 1.2 × 10 −9 m 2 s −1 at 293.15 K. The mutually influencing properties of the fluids during the mixing are linearly interpolated.…”

“…Mixing of fluids is assumed to be an isothermal process which is analyzed by determining the solute concentration c in the system based on the convection-diffusion eqn (2.3). 55 u…”

Modelling the effect of continuous mixer operating parameters on mixture quality

“…Mixers with a screw working element [4,5,6] are more energyconsuming, but can produce better mixtures. High-speed and low-speed circulation mixers [7,8] are applicable for liquids, but problematic for bulk mixtures. Paddle-type mixers require more energy, but they evenly distribute the components throughout the volume of the mixture [9,10].…”