Exchange zone front

Speed of plane kinematic wave Speed of kinematic shock moving up from container bottom True electrophoretic velocity in electrophoresis cell Speed with which a point with ionic fraction Xg in solution moves Electroosmotic velocity in electrophoresis cell Speed of ion exchange zone front Liquid velocity in electrophoresis cell Maximum fluid velocity at center of circular or straight channel with fully developed velocity profile, Eq. (4.2.14) Velocity at free surface of... 

The degree of column utilization before breakthrough requires a knowledge of the shape of the exchange zone boundary or exchange zone front at the time of breakthrough. Approximately,... 

In the particular case of an infinitely fast exchange rate with diffusional effects neglected, the exchange zone front is discontinuous that is, it is a kinematic shock in the sense of Section 5.4 with, for example, the ionic fraction Xg changing discontinuously across the front, which moves downward with speed (Fig. 6.3.3). 

Figure 6.3.4 Effect of equilibrium isotherm shape on shape of exchange zone front.

Fig. 2.4 Schematics of combustion and detonation. 1 Liquid explosives 2 exchange zone of chemical reactions 3 change front width of chemical reactions D spread speed of fronts in liquid explosives...

Another type of ordered structures related to the upwelling in the northwestern part of the sea is represented by cyclonic eddies with a diameter of 10-20 km that leave the coast off Cape Khersones and propagate across the depth contours beyond the shelf zone [22]. An additional contribution to the intra-shelf water exchange in this part of the sea is provided by the eddies (anticyclonic and cyclonic) with diameters about 20-50 km that are formed at the front of the freshened waters related to the Danube River runoff [16,21]. 

Partial displacement of the separated ions from ion exchanger completely saturated with them is provided (Fig. 15b) to concentrate the second component of the mixture. To accomplish this, acidified solution of salts of the separate ions is used. Formed in the column is the stationary front between the acidic and alkaline solution zones. Separation coefficients in the two zones are different. Thus the two principles of operation are combined here as well. 

One important feature characteristic of the processes under consideration should be noted. Movement by the sorption front between alkaline and neutral zones or acidic and alkaline ones relative to the column walls is matched by the movement of the section 1 and 2 border. In particular it becomes possible to carry out separation in a fixed bed of ion exchanger. In both cases, namely using a fixed bed or employing a countercurrent column ion exchanger, regeneration is not required. 

In columns with a fixed bed, ion-exchanger capacity is not completely used since the process is performed up to breakthrough, that is until the appearance of the substance injected into the column in the outlet of the column. So a considerable part of ion-exchange capacity which is within the zone of the sorption front is not used. The counter-current process is carried out so that completely exhausted ion exchanger is in equilibrium with the injected solution when it leaves the column. In this case the capacity is fully used. 

At the back of the combustion chamber a vertical deflecting wall of chamotte keeps the particles from entering into the bum-out-zones of the combustion chamber. The flue gas flows over the upper rim of this deflecting wall to be deviated downwards and eventually upwards by another chamotte wall (dumping wall). The flue gas is then directed through a flow channel between the combustion chamber and the heat exchanger to the front of the combustion chamber and from there into the heat exchanger itself. 

Fig, 3. Distribution of regenerant in an ion exchange bed during regeneration. A — Zone containing all the regenerant B — Diffusive zone of the tail C — Stationary zone D — Diffusive zone of the front... 

In practical combustion systems, the predominant mode of heat transfer is usually not molecular conduction, but turbulent diffusion, except at the boundaries and the flame front. Conduction is the only mode of heat transfer through refractory walls, and it determines ignition and extinction behaviors of the flame. Turbulent diffusion, an apparent or pseudo conduction mechanism arising from turbulent eddy motions, will be discussed in Section 4.4. The relations from the theory of conduction heat transfer15-17 can be used to evaluate heat losses through furnace walls and load zones, and through the pipe walls inside boilers and heat exchangers, etc. 

Bickle JM, Baker J (1990b) Migration of reaction and isotopic fronts in infiltration zones Assessments of fluid flux in metamorphic terrains. Earth Planet Sci Lett 98 1-13 Blattner P, Lassey R (1989) Stable isotope exchange fronts, Damkohler numbers, and flnid-rock ratios. ChemGeol 78 381-392... 

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