Solid reactions, pore plugging model

The pore plugging model for gas-solid reactions given by eqs. (9) and (10) is integrated numerically by the use of orthogonal collocations ( ). The values of c, g, g2 are evaluated at the collocation points as functions of time, in order to evaluate conversion as a function of time, an outer radius, r, is defined so that for each pore the volume of the available solid reactant is given by, 2 2. The value... 

Assume that the reaction and diffusion model is applicable, as presented in section 5,4,3.1, When the Thiele modulus cp > 3, only a fraction of l/(p of the porous particle, close to the outer surface, will take part in the reaction. As the solid is converted to a solid product with a larger volume, the pore diameter will decrease. The effective diffusivity is thereby reduced, so that the thickness of the reaction zone is also reduc. The higher the reaction rate constant, the higher the Thiele modulus was at the beginning, and the sooner the pore mouth will be plugged. A rough estimate indicates that the maximum degree of conversion of the solid reactant will be smaller than the effectiveness factor, which is tank (p/(p. 

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