The Ergun equation is given by: \[ \Delta P = \frac{150 \cdot (1-\epsilon)^2 \cdot \mu \cdot U}{d_p^2 \cdot \epsilon^3} + \frac{1.75 \cdot (1-\epsilon) \cdot \rho \cdot U^2}{d_p \cdot \epsilon^3} \] where: - \(\Delta P\) = pressure drop - \(\epsilon\) = void fraction (porosity) of the bed - \(\mu\) = viscosity of the fluid - \(U\) = superficial velocity of the fluid - \(d_p\) = diameter of the particles - \(\rho\) = density of the fluid
