Tortuous path concept

Electrodialysis equipment and process design The performance of electrodialysis in practical applications is not only a function of membrane properties but is also determined by the equipment and overall process design. As far as the stack design is concerned there are two major concepts used on a large scale. One is the sheet-flow concept, which is illustrated in Figure 5.3 and the other is the so-called tortuous path concept, which is illustrated in Figure 5.5. 

Where P is the permeability, ( ) is the volume fraction and a is the aspect ratio of the layered silicate used. The permeability of a nanocomposite can be enhanced by using higher concentration of layered silicate with higher aspect ratio. Note that the clay concentration should not exceed the optimum concentration beyond which layered silicates are agglomerated. That means the layered silicate should be well dispersed. The reduced permeability in case of nanocomposite can be explained by considering a tortuous path concept. Because of the presence of impervious silicate layers, a permeant has to follow a tortuous path compared to a smooth one in pure polymer as shown in Figure 7.14. 

Because they do not obey the octet rule, hypervalent molecules have often been thought to involve some type of bonding that is not found in period 2 molecules. Ideas concerning the nature of this bonding have developed along a somewhat tortuous path that it is interesting and instructive to follow. We will in the end conclude that the nature of the bonding in these molecules is not different in type from that in related period 2 molecules and that there is therefore little justification for the continued use of this concept. 

Figure 5.5 Schematic drawing illustrating the sheet-flow and a tortuous-path spacer concept.

Opposiny-reactants mode. When immobilized with a catalyst or enzyme, the interconnected tortuous pores or the nearly straight pores of a symmetric inorganic membrane provides a relatively well controlled catalytic zone or path for the reactants in comparison with the pellets or beads in a fixed or fluidized bed of catalyst particles. This unique characteristic of a symmetric membrane, in principle, allows a novel reactor to be realized provided the reaction is sufficiently fast. The concept applies to both equilibrium and irreversible reactions and does not utilize the membrane as a separator. Consider a reaction involving two reactants, A and B ... 

Fracture mechanics concepts have also been applied to predict the behaviour of natural fibre FRC. Fracture parameters were found to be dependent on the moisture content, with wet composites having higher toughness values [40,51], Wet composites were also found to be notch-insensitive, suggesting that LEFM cannot adequately model the behaviour of such composite [51 ]. This was probably the result of the cracking mode, in which the crack path was tortuous, with some fibres failing by pull-out. 

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