Heterogeneous Model with Shrinking Unreacted Core

3 HETEROGENEOUS MODEL WITH SHRINKING UNREACTED CORE 

The model equation is again (4.2-1) in which the time derivative is set equal to zero, as implied by the pseudo-steady-state approximation  

Substituting (4.3-5) into (4.3-2) taken at r = / and considering that for large f) the expression cj) coth - 1 reduces to yields 

The continuity equation for A, (4.3-1), can be integrated twice to yield the following expression for the concentration profile of A  

The concentration of A at the reaction front is obtained by setting r = r in equation (4.3-7). 

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Heterogeneous Model with Shrinking Unreacted Core ... 

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