Tortuous flow

FIG. 22-59 Schematic of two ways to pass solution across an ED membrane. Tortuous flow (left) uses a special spacer to force the solution through a narrow, winding path, raising its velocity, mass transfer, and pressure drop. Sheet feed (right) passes the solution across the plate uniformly, with lower pressure drop and mass transfer. Coutiesy Elsevier.)... 

Chemical Phase Inversion Symmetrical phase-inversion membranes (Fig. 20-67) remain the most important commercial MF membranes produced. The process produces tortuous-flow membranes. It involves preparing a concentrated solution of a polymer in a solvent. The solution is spread into a thin film, then precipitated through the slow addition of a nonsolvent, usually water, sometimes from the vapor phase. The technique is impressively versatile, capable of producing fairly uniform membranes whose pore size may be varied within broad limits. 

Time intervals permitting displacement values in the scaling window a< )percolation model [4]. Hydrodynamic dispersion then becomes effective. For random percolation clusters, an anomalous, i.e., time dependent dispersion coefficient is expected according to... 

D. Ball, Plug, and GatO Valves. The valves discussed above often introduce considerable restriction into the system because of small orifices and tortuous flow patterns. Such restrictions are not serious for most applications at 1 atm pressure or above, but they may be unacceptable for vacuum applications, where small-diameter openings are a serious impediment (see Chapter 6). Ball and... 

Fig. 1.5. Schematic illustration of the tortuous flow path in the packed segment of a CEC column.

Small volume elements of fluid take a tortuous path on flowing through the interstitial pore space of porous materials. The fluid elements must dodge from side to side in order to avoid the solid matter in their path. Such tortuous flow is illustrated in Figure 4.3 and brings to mind a boulder-filled river in which the current veers erratically to find channels between the randomly placed rocks. 

In this highly exothermic reaction, kinetic control is a function of the catalyst characteristics and surface temperature, and the mass transport control and boundary layer thickness is based on the catalyst bed geometry and flow velocity. Both the gauze and ceramic foam have tortuous flow paths, but the extruded cordierite monolith has microchan-... 

A simple way to maintain interfacial area and dispersion in a vertical gravity-flow column, and to reduce axial mixing, is to fiU the column with loose packing to provide tortuous flow paths. Typical packing consists of ceramic rings or saddle shapes, dumped in random arrangement. The... 

Figure 6.11 Gasket for tortuous flow and sheet flow.

Reticulated ceramic foams are sponge-like structures with open accessible pores in the range 10 to 100 per inch and an interconnecting porosity in the range 75-90%. They have low resistance to fluid flow, and the tortuous flow path generates considerable turbulence [1]. Consequently, they have attracted considerable attention as potential catalyst supports [2,3]. 

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