Pipe mixer

Fig. 5. Mixing in the partitioned pipe mixer, (a) Schematic view of the mixer geometry one element of the mixer is shown, and the mixer comprises several such elements joined together, (b) KAM surfaces in flow bounding regions of regular flow, (c) A and B show examples of experimentally obtained streaklines undeformed streaklines pass through KAM tubes, whereas streaklines in the chaotic region are well mixed. The white arrows indicate the location of a companion streak-tube. (Khakhar, Franjione, and Ottino, 1987 Kusch and Ottino, 1992).

Duct flows can be converted into efficient mixing flows (i.e., flows with an exponential stretch of material lines with time) by time- modulation or by spatial changes along the duct axis. One example of the spatially periodic class is the partitioned-pipe mixer (PPM). This flow consists of a pipe partitioned with a sequence of orthogonally placed rectangular plates (Fig. 5a). The cross-sectional motion is induced through rotation of the pipe with respect to the assembly of plates, whereas the axial flow is caused by... 

Khakhar, D. V., Franjione, J. G. and Ottino, J. M., A case study of chaotic mixing in deterministic flows the partitioned pipe mixer. Chem. Eng. ScL 42,2909-2926 (1987). 

This double-pipe mixer contained as connection module a sort of T-piece as an outer shell to connect and fix three outer capillaries for two inlet flows and one outlet flow [134], One tube of relatively large diameter was passed through two openings of the T-frame, so that the tube end was at the level of the end of the... 

The double-pipe mixer was designed and so far only used for contacting and reacting immiscible fluids [134], The respective flow-pattern maps were derived and annular and slug flows as well as complete spread of the inner-tube fluid were identified as distinct regimes. Since in this chapter only miscible liquids are concerned, no protocol and no results are given for the mixer below. H owever, the device is mentioned, since it could in principle be used also for mixing miscible fluids. 

M 81] [P 70] A plot of the normalized intensity versus the down-channel length clearly shows that the mixing efficiencies of the devices have the following sequence barrier-embedded helical mixer > helical mixer pipe mixer (see also Figure 1.165) [3]. The relative degree of mixing performance is lower for the pipe mixer than for the other two helical mixers. This is most evident for the three plots with Re > 13.96. 

Figure 4. A schematic of one period of the partitioned pipe mixer, along with the form of the streamlines in one cross section. Reprinted with permission from Chem. Eng. Sci., vol. 42, p. 2909, D. V. Khakhar, J. G. Franjione, and J. M. Ottino, A Case Study of Chaotic Mixing in Deterministic Rows The Partitioned Pipe Mixer, copyright 1987 [32], Pergamon Press PLC.

Sulzer SMV mixer orifice/baffle plate 0 pipe mixer Kenics/Chemineer mixer / Schaschllk mixer... 

The simplest flow that can exhibit chaos is two-dimensional flow. Ottino and co-workers (Chien et al., 1986 Khakhar et al., 1986 Leong and Ottino, 1989) produced chaotic mixing in simple prototypical devices, such as cavity flow, partitioned-pipe mixer (e.g., a Kenics static mixer as discussed in Section 8.5), and eccentric helical annular mixer with Newtonian fluids. Of prime interest in the area of polymer processing, of course, is the work in cavity flows. A typical cavity was constructed with the ability of movement of both top and bottom plates. Typical cavity flow, which is described in Chapter 8, corresponds to the steady movement of the top plate only. However, corotational (in the opposite direction) movement of both plates in a periodic fashion induces chaos in the cavity. Leong and Ottino (1989) used two types of movement discontinuous and continuous in a sinusoidal manner (Fig. 6.28). In the discontinuous corotational flow, the top plate first moves for a half period, then it stops for 5 s, and the cycle ends with the bottom plate moving for a half period in the opposite direction. In the continuous type of movement, both plates move sinusoidally at the same time, but with a phase difference of %/2. 

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