Thin-channel flow, schematic

Let s use the steady, two-dimensional flow in a thin channel or a narrow gap between solid objects as schematically represented in Fig. 5.11. The channel height or gap width... 

In FLM, the LM organic solution flows in a thin channel between two hydrophobic microporous membranes separating the LM phase from an aqueous feed and strip solutions. The FLM differs from the HLM and MHS modules with hydro-phobic membranes by application of a spiral-type module. A schematic diagram of the spiral-type FLM module is shown in Figure 13.11. 

FlFFF separations are usually performed in thin channels constructed with flat beds. Figure 4 shows a schematic of a symmetrical channel (19). In this design, the force field is created by flowing a liquid across the channel perpendicular to the normal flow down the channel. This flowing is accomplished by using semipermeable membranes as both channel walls—solvent can flow through the membranes, but particles are retained within the channel for the separation. The remainder of the apparatus is quite similar to that previously described for SdFFF. Sample loading and detection is performed in the same manner. 

Figure 7d shows a schematic depiction of the active mixer chip design, consisting of a main flow channel and six pairs of orthogonal side channels [76]. Operation of the mixer chip relies on the perturbation of the main x-directional channel flow by y-directional cross-stream side-channel flows. The side-channel flows are per-turbated by pressure changes through thin membranes affected by a GERF microvalve (Fig. 7e). Square-wave electrical voltage signals (0-800 V) are applied between the electrodes to control the microvalve and, in turn, the perturbation, leading to pulsating sinusoidal cross-stream flows in the six pairs of side channels, as shown in Fig. 8f.

Figure 5.8 shows schematically a design architecture concept of metal plates [29]. The thin anode and cathode plates were stamped to form a hydrogen flow field and air/oxygen flow field, respectively. The coolant flow field was formed simultaneously and the closed channel was generated when the anode plate and cathode plate were bonded together. The cross-section shape of the flow field or flow channel varies depending on the required flow supply in the specific fuel cells. 

One commonly used device for controlling the zeta potential is the flow FET [7-9]. The basic principle of the flow FET is that a constant perpendicular electric fleld from a side channel is used to modify the local zeta potential. A schematic of a typical flow FET is shown in Fig. 3. The device consists of a main channel and a side channel, separated by a very thin wall (nanometer to micron size). In a flow FET, the working fluid moves only through a main microchannel (horizontal) from the... 

In capillary electrophoresis and electrochromatography, separations occur in a buffer-filled capillary tube under the influence of an electric field as seen in the schematic of Figure 30-1. Separations in field-flow frac-tioitation, on the other hand, occur in a thin ribbon-like flow channel under the influence of a sedimentation, electrical, or thermal field applied perpendicular to the flow direction. 

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