#### Pressure Drop in Packed Bed Reactors: Screencast

Describes how to use the Ergun equation to calculate the pressure drop in a packed bed.

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##### Important Equations:

Ergun equation for pressure drop in a packed bed:

\[ \frac{dP}{dz} = -\frac{(1\, -\, \phi)\nu }{D_p \,\phi^3 A_c} \left[ \frac{150 (1 \,- \,\phi) \mu}{D_p} + \frac{1.75(\rho \nu)}{A_c} \right]\]

where \(P\) = pressure

\(z\) = distance down the reactor

\(\phi\) = void fraction (volume of tube not occupied by particles)

\(\nu\) = volumetric flow rate

\(D_p\) = diameter of particles in packed bed

\(A_c\) = cross-sectional area of tube

\(\mu\) = viscosity of gas

\(\rho\) = mass density

For an ideal gas

\[\nu = \frac{F_T RT}{P}\]

where \(F_T\) = total molar flow rate

\(R\) = ideal gas constant

\(T\) = absolute temperature