Formation of Pure Thermal Wave

A pure thermal wave is always a shock and from Eq. (9.36) it is clear that its velocity is given by o/(l + [(1 - f)/i.]CjC ) while the velocity of the mass transfer front is given by o/ l +[(1 - e)/e]d(j dc. For the thermal wave to precede the concentration front (adsorption) therefore requires dq /dc o Cs / Cf while for a pure thermal wave lagging the concentration front to be formed during desorption (dq /dc Q CjCy. At the watershed point Tn), dq /dc o = CJC and the velocity of the limiting proportionate-pattern wave is the same as that of the thermal shock. A more detailed discussion of the conditions of thermal wave formation and the practical importance of this type of behavior has been given by Basmadjian.  

The behavior of a bed with initial loading in region II is somewhat similar except that in the case of a low-temperature purge the simple waves are replaced by shocks. This situation is discussed in detail by Rhee and Amund- 

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