Liquid chromatography (LC) flow can be model as a packed bed and is described by the Ergun equation. LC systems are often packed with dextran gel beads. Your boss has asked you to explain mathematically why two LC systems have different pressure drops. The first system is packed with spherical 120-micron beads in a 55cm depth column. The average void fraction is 0.37. The pressure drop is 110 psig. The second system has the same beads with a bed depth of 95cm. However, the pressure drop is 700 psig. The average void fraction is 0.32 in the longer column due to some compaction of the spheres to cylinders near the outlet. Accounting for the change is void fraction, does this explain the difference in pressure drop? What else could be the cause? Provide detailed explanation along with calculations.