Micromixer T-shaped

Ruy et al. have performed a similar reaction under microreactor conditions in a multiphase solvent system containing an ionic liquid as the catalyst carrier and reaction promoter [35]. Their system consisted of two T-shaped micromixers (i.d. 1,000 and 400 pm) and a capillary stainless steel tube as an RTU (1,000 pm i.d. and 18 m length, giving a 14.1 ml volume), equipped with pumps and control valves. Under the optimized conditions, Pd-catalysed carbonylation of aromatic iodides in the presence of a secondary amine provided only the double carbonylated product, ot-ketoamide, while the amide obtained by the single carbonylation was observed in high quantities only when the reaction was performed in batch (Scheme 13). 

Following similar trials with the formation of diarylbenzenes [63-65], the same research group has reported a multistep synthesis of photochromic diarylethenes using a microflow system that contained two linked micromixers and microreactors (MRi 2) [66]. Similarly to the previously reported linked microreactors, the reactors used in this setup were made of stainless steel tubes and T-shaped micromixers. Initial experiments were conducted in two steps in a continuous sequence to afford symmetrical octasubstitued diaryUiexafluoro cyclopentene (Scheme 29). 

Figure 6. T-Shaped micromixer formed by die intersection of two microchannels, showing a schematic of the mixing or dilution process.

Figure 7. Eleotroosmotic streamlines at the midplane of a 50pm T-shaped micromixer for the a) homogeneous case with = -42 mV, b) heterogeneous case with six offset patches on the left and right channel walls. All heterogeneous patches are represented by the crosshatched regions and have a = + 42mV. The applied voltage is (baoD = 500 V/cm.

Figure 8. 3D species concentration field for a 50pm x 50pm T-shaped micromixer resulting from die flow fields shown in Figure 7. (a) homogeneous case, and (b) heterogeneous case with offset patches. Species diffiisivity is SxlO mVs and zero electrophoretic mobility are assumed. 

In the case of Y- or T-shaped micromixers, a decrease in the channel width to shorten mixing time leads to a decrease of production volume per unit time. To solve this problem interdigital multilamination micromixers have been developed. In this type of micromixer, two fluids are separated into many small narrow streams, which are arranged to contact each other alternately. The mixing takes place at interfaces of such sub-streams by molecular diffusion. The IMM (Institute of Microtechnik Mainz) single... 

Although T-shaped micromixers are very simple in structure and are easy to fabricate by conventional mechanical machining technology, they can be very effective in achieving fast mixing (Figure 7.14). At a low flow... 

Figure 7.14 T-shaped micromixer showing the laminar and engulfment regimes...

A monomer solution and an initiator solution are mixed at a T-shape micromixer Ml and microtube reactor Rl. In this case fast mixing of the two solutions is not important, because radical polymerization does not start until the temperature is elevated sufficiently for thermal decomposition of a radical initiator, such as AIBN. Therefore, the combination of a T-shape micromixer and a short microtube reactor is sufficient for producing a homogeneous solution before polymerization starts. 

Figure 9.9 Microflow system for polymerization. Ml, T-shape micromixer Rl, R2, R3, microtube reactors...

Fig. 7.1 T-shaped micromixer for electrokinetic instability induced mixing [79. ...

Fig. 1 T-shaped micromixer with two input fluids, each containing one diffusing species. L and w represent the length and width of the mixing channel, respectively (Adapted with permission from [58]. Copyright 1999 American Chemical Society)...

Fig. 6 Flow microreactor system fen- polymerization of vinyl ethers initiated by TfOR M T-shaped micromixer, R microtube reactor...

Fig. 8 Flow microreactor system for cationic polymerization of 1,4-diisopropenylbenzene initiated by TfOH. M T-shaped micromixer, /f microtube reactor...

Fig. 13 Integrated flow microreactor system for the synthesis of block copolymers having two different polymer chains on a silicon core. Ml, M2, M3, M4 T-shaped micromixers R1, R2, R3, R4 microtuhe reactors...

Fig. 14 Flow microreactor system for anionic polymerization of styrene in cyclohexane at 80°C initiated by s-BuLi. M T-shaped micromixer R microtube reactor...

Fig. 16 Flow microreactor system for anionic polymerization of alkyl methacrylates initiated by 1,1-diphenylhexyllithium. Ml, M2 T-shaped micromixers Rl, R2 microtube reactors...

Fig. 20 Flow microreactor system for the free-radical polymerization initialed by AIBN and relative rate of the polymerization in the flow microreactor. M T-shaped micromixer Rl, R2 microtuhe reactors...

Ooms T, Lindken AR, Westerweel J (2009) Digital holographic microscopy applied to measurement of a flow in a T-shaped micromixer. Exp Fluids 47 941-955... 

Figure 4.8 T-shaped micromixer [14]. (Adapted with permission from Wiley.)...

More information on laminar flow in channels and ducts can be found in publications by Knoeck [5] and Shah and London [9]. Transient flow regimes in T-shaped micromixers have a large influence on mixing and chemical reactions [10]. 

N. Kockmann, S. Dreher, P. Woias, Unsteady laminar flow regimes and mixing in T-shaped micromixers. Technical Paper, ASME 5th International Conjerence on Nano-, Micro- and Minichannels, Puebla, Mexico, 2007, ICNMM2007-30041. 

Figure 4.3 X-PIV raw image T-shaped micromixer mixing channel width = 400p,m, inlet channel width = 200pm image 1 ti (a) image 2 t2 = ti -F At with At = 2ps (b).

Figure 4.5 Velocity field-entrance region of a T-shaped micromixer [4].

This technique for calculating the out-of-plane component was recently applied to microfluidic flows [4, 6]. With the knowledge of the third velocity component iv it is possible to visualize the 3D structure in the entrance region of a T-shaped micromixer, as shown in Figure 4.6. The out-of-plane component w is unequal to zero. 

Figure 4.8 Three-dimensional velocity field of of-planecomponentofthevelocity,z-component stereo- X-PIV measurements in the mixing zone is displayed colour coded. Only the lower half of of a T-shaped micromixer at Re = 120. The flow is the 3D scan from z = 22 to lOOpm in the center of laminar and station a 7. The in-plane velocity the channel ofthe 800 x 200 Xm cross-section is distribution is presented as vectors and the out- shown [12] (by courtesy of Springer-Verlag).

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