EM model with a chemical reaction

The implementation, within a numerical model, of the EM model with a chemical reaction can prove delicate, even though the evolution equations (equation [12.30]) are simple. The average concentrations (Ca)(0 and (Cb)(0 evolve with time, and their values have to be recalculated at every time step. If this calculation is not performed accurately, the equations of the model will cause, through error, the production or consumption of products in addition to the effects of the reaction mechanism. 

In a perfectly stirred closed reactor, it is easy to compute the average concentrations at any time  

Utilization of the lEM model is more delicate when an open reactor is considered, or when the reactor is non-homogeneous. It is essential to be specific about the domain that defines the vicinity of a EFP, so that the mass balance would not be distorted. We shall not discuss this fact further herein, as our concern is to draw attention of the reader on this relative disadvantage of the lEM model. 

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