Micromixer recombination-type

When a T-shaped mixer is used, the product selectivity is essentially the same as for the macrobatch reactor (Scheme 6.4). The use of the YM-1 mixer, a splitting-and-recombination-type micromixer (see Chapter 7), increases the selectivity, however, a significant amount of dialkylation product is still produced. The use of the IMM multilamination-type micromixer results in excellent selectivity of the monoalkylation product. The amount of dialkylation product is very small. Therefore, the product selectivity strongly depends on the manner of mixing. 

Fork-like chip micromixer - tube reactor and other micromixers This split-recombine type of reactor has fork-like segments which are machined on a silicon plate by micromachining. As in other micromixers. this mixing unit is coimected to conventional tube for residence time enhancement reasons... 

Figure 3.9 shows the structure of a Toray Hi-mixer, [5] which is one example of such a split- and recombination-type micromixer. This mixer divides the solution into four at a time, and thus, the two layers introduced initially are split into eight layers at the first element and then into 32 layers at the second element, making the diffusion distance short very quickly. 

Fig. 3.9 Mixing in a Toray Hi-mixer (a manifold split and recombination-type micromixer)...

Manifold split-and-recombination micromixers are also popular and powerful micromixers. " In this type of micromixer, two solutions to be mixed are introduced into a channel and combined. Then, the mixture is split into two streams in such a way that each stream contains segments of two different solutions. The two streams are then introduced into the next channel and recombined so that the number of solution segments increases, as shown in Figure 7.10. 

The Toray Hi-mixer is a special type of manifold split-and-recombination micromixer. The structure of the Hi-mixer is shown Figure 7.12. In the Hi-mixer, when two layers of the solutions enter the mixing element, they are split into eight layers by using twist walls in the element. Therefore, in this method, the number of layers increases exponentially by repeating the operation (4" after the wth iteration). 

The Yamatake YM-1 micromixer is another type of split-and-recombination micromixer (Figure 7.13). As shown in Figure 7.13, the two solutions to be mixed are distributed into many streams in the first part of the mixer. Then, several split-and-recombination operations are performed sequentially to increase the number of segments, leading to fast mixing because of the short diffusion path. 

Similar to parallel lamination micromixers, sequential lamination micromixers [also called split-and-recombine (SAR) micromixers] rely on an exponential increase in the contact surface area and decrease in the length path to achieve a shorter mixing time. The difference between the two types of micromixers is the method used to achieve lamination of the fluid to be mixed. As suggested by the name, the lamination in sequential lamination micromixers is obtained by sequential processes of splitting and rejoining the fluids (Fig. 4a) [84, 86-89]. 

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. 

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)...

Concerning mixing of highly viscous media, it may worth mentioning the type of split-and-recombine micromixers exemplified on the so-called Caterpillar Micro... 

Figure 22.13 Micromixers employed in the experimental setups for surfactant dispersion. The V-type mixer of FZK (a) is a parallel multilamination micromixer whereas the caterpillar mixer of IMM (b) is a split-and-recombine micromixer (serial multilamination) [3].

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