Dispersion in Packed Beds: Non-Newtonian Effects — Lesson 2

This lesson covers the concept of dispersion in packed beds, focusing on non-Newtonian fluids. It explains how to derive an equation for dispersion in packed beds and discusses the mechanisms of dispersion, including molecular diffusion and mixing arising from flow patterns within the fluid. The lesson also highlights the importance of dispersion in packed beds, explaining how it affects the performance of packed beds and why it is more significant in packed beds than in simple pipe flows. It further discusses the effects of dispersion on concentration variation and the factors that influence dispersion, such as flow regime and bed geometry. The lesson concludes with a discussion on how to measure dispersion coefficients in gases and liquids.

Video Highlights

01:53 - Discussion on the impact of dispersion on the performance of packed beds.
06:40 - Discussion on the impact of low flow rates or small Reynolds numbers on dispersion, with molecular diffusion dominating.
13:37 -Derivation of the differential equation for dispersion in a cylindrical bed of voidage epsilon.
38:25 - Discussion on the experimental results for dispersion coefficients in gases and liquids.

Key Takeaways

  • Dispersion in packed beds is a self-induced mixing process that arises during the flow of fluids.
  • Two mechanisms of dispersion are molecular diffusion and mixing arising from flow patterns within the fluid.
  • Dispersion affects the performance of packed beds and is more significant in packed beds than in simple pipe flows.
  • Dispersion influences concentration variation and is influenced by factors such as flow regime and bed geometry