Split-recombine mixer

All types of split-recombine mixers generally have high volume flows (e.g. 1001 h and more at moderate pressure drops) at favorable pressure drops (not exceeding 5 bar) as their internal micro structures can be held large [41,42,48,49]. 

Central part of this reaction unit is a split-recombine chip micro mixer made of silicon based on a series of fork-like channel segments [32-36]. Standard silicon micro machining was applied to machine these segments into a silicon plate which was irreversibly joined to a silicon top plate by anodic bonding (Figure 4.16). 

Schonfeld, E., Theoretical and experimental characterization of a low-Reynolds number split-and-recombine mixer, Micrqfluidics Nanofluidics 2(3)... 

Interdigital mixers and micromixer with the split-recombine technique Single microchannel operating in annular flow regime Microstructured falling film reactor Mesh microreactor... 

Sprogies et al. compared micromixers for use in extractions based on emulsions [32]. They revealed that a multilamination mixer is more efficient than a simple T-junction, whereas a nozzle-type mixer and a split-and-recombine mixer show the best results for emulsification and thus for extraction. 

For the case of the homogeneous reactions considered in this chapter (the majority being in the liquid phase), parallel channel arrangements were also developed. Most often, a low degree of parallelization is needed to achieve the desired throughput, e.g. less than 10. This is used, for example, in several split-and-recombine mixers such as the fork-mixer array [55]. 

Nitration of naphthalene using N2O5 Interdigital mixers and MSR with the split-recombine technique Antes et al. [34]... 

Figure 20.10 Schematic drawings of typical micromixers used for emulsification V-Type MicroMixer (FZK, left), P-Type MicroMixer (FZK, middle) and Caterpillar Split-Recombine Microstructured Mixer [66] (IMM, right)...

Figure 20.12 Influence of the pressure and pressure ratio on the droplet size of an oil-in-water emulsion produced by a Caterpillar Split-Recombine Microstructured Mixer.

Static mixers. Static mixers are manufactured from thin metal strips with the same width as the tube internal diameter. In contrast with twisted tapes, the helix is not continuous. The flow is caused to twist through 180° and then twist in the reverse direction through 180°, and so on. The continuous splitting, reorientation and recombination of the fluid cause the enhancement as it flows through the insert. 

This approaches the performance of conventional static mixers, closing the gap between this smallest class of industrially used apparatus and micro mixers for analytical purposes [130], Thus, a toolbox of microstructured mixers is available for the whole range of flow rates. This box comprises interdigital multi-laminating with a few ml h 1 capacity and split-and-recombine micro mixers (caterpillar type) up to 1001 h 1 as well as interdigital concentric microstructured mixers (StarLam type) series achieving 300, 1000 and up to 3000 1 h, dependent on the respective sub-version. 

Mixer 56 [M 56] Mdbius-type Split-and-recombine Micro Mixer... 

Another Mobius-type mixer is described in [142], Again, a two-fold 90° rotation is said to be the basic principle, doubling the number of layers for laminar flow. After the first rotation, the laminated fluids are split and thereafter recombined, restoring the original geometry. 

This micro mixer extends the SAR concepts mentioned above, the sequential lamination being actively supported by the use of a separation plate for flow splitting (see Figure 1.126) [140], As a result of the splitting, two sub-channels are formed, initially at the same height level within the device. Then, one of these sub-channels undergoes a downward movement in a lower level of the device. The two flow channels are so sandwiched, the first carrying the two fluids separate from each other. At certain locations there are conduits within the sandwich to achieve flow recombination on one of the levels of the sandwich. This procedure is repeated many times. 

M 60] [P 54] The impact of having truly separated flows was shown by CFD simulations [7]. An essential part of the flow splitting, besides having split channels which recombine later, is a splitting plane which cuts the flow like a knife. These design aspects are central parts of an optimized SAR caterpillar mixer. 

C., An optimized split-and-recombine micro mixer with uniform chaotic mixing, Lab Chip 2004, 4, 65-69. 

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