Dispersion and Conversion in Empty Pipes

Axiai Dispersion Modei for Laminar Fiow in Round Tubes The exact two-dimensional equation for laminar flow in tubes is given by Eqs. (4.10.27) and (4.10.28)  

If radial diffusion is relatively large and the radial concentration profile has a chance to stabilize, that is, if the length-to-diameter ratio is sufficiently large, the 

Interval A0 Average intervall Average , interval interval, interval ( interval) (interval Atf 

This approach is different than if we were to neglect the influence of molecular diffusion as done in Section 4.10.2.4 to derive the equation for the conversion in a tube with laminar flow and negligible molecular diffusion, Eq. (4.10.29). 

Equation (4.10.117) expresses that a tubular reactor is formally represented by axial dispersion superimposed on plug flow. The dispersion coefHcient is then needed, for example, based on the measurement of the residence time distribution or based on correlations for D x- Note that D x considers axial convection, molecular diffusion, and the effect of the radial velocity profile. 

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