Multi flow pattern

This class of hybrid components comprises chip micro-reactor devices, as described in Section 4.1.3, connected to conventional tubing. This may be H PLC tubing which sometimes has as small internals as micro channels themselves. The main function of the tubing is to provide longer residence times. Sometimes, flow through the tube produces characteristic flow patterns such as in slug-flow tube reactors. Chip-tube micro reactors are typical examples of multi-scale architecture (assembly of components of hybrid origin). 

Figure 4.23 Near-ideal multi-lamination flow patterns in the second-generation caterpillar mini mixer as a result of introducing a splitting plate and improving micro structure geometry [50],...

This plate cuts the flow into pieces which are better defined than the poorly defined ones obtained by the first-generation caterpillar mini mixer. In addition, the micro structure geometry was improved by means of simulation. As a result, near-ideal multi-lamination flow patterns were yielded (Figure 4.23), which showed excellent correspondence with simulation [50]. 

Multiphase copolymers, Ziegler-Natta catalysts for, 26 535, 537-540 Multiphase laminar flow patterning, in microfluidics, 26 961 Multiphase reactions, in microbial transformations, 16 412-414 Multi-phase reactors, 21 333-335 Multiphoton effects, in photochemical technology, 19 109... 

Figure 1.89 Multi-lamination flow patterns in the rectangular interdigital micro mixer for various flow rates [20] (by courtesy of AlChE).

When using an asymmetric flow ratio (5 1) for still better flow visualization, the regularity of the multi-laminated pattern is the most striking feature (see Figure 1.92) [39]. 

M 46] [P 34] A multi-lamination pattern was evident in the central and inner parts of the flow when entering a triangular focusing section with re-directed flow ( 90°) [34], The outer part, i.e. close to the channel walls, was disordered, probably owing to flow maldistribution. 

Hence, the main information is that the in-line concentration profiles confirm the uniform multi-lamellae formation over a favorable large range of flow rates given already by photographic flow-pattern imaging (see Multi-lamination patterns) [20],... 

Jet flow patterns created from multi-lamination patterns... 

Figure 1.98 Pure multi-lamination flow pattern (top, 10 ml h-1) and superposed by focusing and reopening/jet formation (bottom, 2 I h-1) in the slit-shaped interdigital micro mixer visualized by blue-colored water dilution imaging [20] (by courtesy of AlChE).

Flow patterns in concentrically multi-layered droplet mixers... 

Flow patterns in planar multi-layered stream mixers... 

For increased flow rates, however, the CFD simulations show more and more deviations from an ideal SAR multi-lamination pattern [7]. Since inertial forces come into play, a secondary flow pattern is superposed on the SAR velocity profile of the creeping flow regime. Streamlines seeded at the initial lamellae interface in top view for various Reynolds numbers. The lamellae pattern right at the outlet for the same set of Reynolds numbers were also given. Further simulations showed that for Re above -15 the center lamellae are thinned out until they detach from the top and bottom walls for Re 30 (see center image of Figure 1.128). 

The interfacial and turbulence closures suggested in the literature also differ considering the anticipated importance of the bubble size distributions. It thus seemed obvious for many researchers that further progress on the flow pattern description was difficult to obtain without a proper description of the interfacial coupling terms, and especially on the contact area or projected area for the drag forces. The bubble column research thus turned towards the development of a dynamic multi-fluid model that is extended with a population balance module for the bubble size distribution. However, the existing models are still restricted in some way or another due to the large cpu demands required by 3D multi-fluid simulations. 

The field of membrane separations is radically different from processes based on vapor-liquid or fluid-solid operations. This separation process is based on differences in mass transfer and permeation rates, rather than phase equilibrium conditions. Nevertheless, membrane separations share the same goal as the more traditional separation processes the separation and purification of products. The principles of multi-component membrane separation are discussed for membrane modules in various flow patterns. Several applications are considered, including purification, dialysis, and reverse osmosis. 

Flow discharge angles are important for multi-impeller configurations. If flow from adjacent impellers fails to communicate, separate circulation zones develop. This is seldom desirable. Harvey [4] shows the effect of multiple impellers on flow patterns in Figure 9.14. CFD analyses are shown on the left, and experimental laser Doppler flow measnrements are shown on the right. 

An essential feature of this new design is a better controlled gas flow pattern in the coating zone. This is achieved by application of a guiding system in which the gas flow is accelerated, stabilized, and given a precise amount of swirl, which eliminates slugging, often seen in traditional coaters, and stabilizes multi-tube systems. Particles are... 

---