Isothermal axial flow bed

If the fixed bed can be considered to operate under isothermal conditions (as in the case of kinetic measurements [120], some laboratory-scale fixed beds, and packed microreactors [121]), the previously described mass balances are the only equations required. In this case, = T and the particle is also considered 

Equation 3.71 must be solved with the following boundary conditions  

An estimate for Cq is required (only for purposes of calculating a small correction), and it can be obtained from averaging Equation 3.67  

The correction to the pseudo-homogeneous model is positive ((ci) 0), which shows how the presence of isothermal interphase resistance decreases the reactor s conversion Xpu = 1 - (co) is an upper bound). 

Even though axial difiusion effects are not considered (making the analysis of the inlet region as z 0 incomplete), it is possible to obtain an estimate for the axial distance below which the pseudo-homogeneous approach is valid for a given Sy from (3.76)  

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