Microstructured caterpillar

Figure 4.22 Second-generation caterpillar mini mixer with splitting plate and improved microstructure geometry [50].

A caterpillar steel mini mixer can be connected to conventional tubing, either stainless steel or polymeric, to prolong the residence time. The caterpillar mixer as all types of split-recombine mixers, profits from high volume flows (e.g. 100 1 h and more at moderate pressure drops) at favorable pressure drop (not exceeding 5 bar) as its internal microstructures can be held large [25-28]. 

Reactor type Caterpillar mini mixer-tube reactor, 1st generation Microstructure in one plate initial depth maximum depth 600 pm 850 pm... 

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. 

Figure4.44 Bas-relief micromixer with microstructured ramps in the channel floor and ceiling, termed caterpillar micromixer (by courtesy of IMM).

Caterpillar microstructured mixer-reactors owe their name to their total micro-channel shape, characterized by alternately up- and down-lifting ramps at the floor and ceiling of the fluid path, which as a whole resemble the fringes along the body... 

Fig. 6.16 Cream manufacturing plant (top) and its core element, the microstructured eight-component caterpillar mixer (bottom).

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.

The Caterpillar micro mixer is an example of a simple, pilot-sized micro mixer-tube reactor that has an internal microstructure with a ramp-like shape inducing recirculation flow patterns, whereas the overall channel structure can be kept fairly large. The volume varies between 1 L/hr to several hundred liters per hour. Several hundreds of precision-engineered, star-shaped platelets can be stacked, and the flow can be distributed. 

Bas-relief micromixers induce transversal motion, when miscible liquids are considered, to mix by convection [92,93]. In the gas-liquid case to be considered here, the mechanism for bubble formation is yet unclear, but likely related to shear forces coming from a similar liquid motion in the dispersed flow. Caterpillar mixers induce such transversal motion by ramp-like microstructures, lifted up and down, placed in one channel at the bottom and ceiling [4] (see also Ref. [S6]). Caterpillar mixers were developed as family of devices with grouped capacity using smart enlargement of the internal chaimel and have high volume flows, for example,... 

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