Adsorption and Pore Condensation — Lesson 3

This lesson covers the concept of flow through porous media, focusing on the transport mechanisms applicable in this context. It delves into the different types of flow, such as viscous flow, Knudsen diffusion, surface diffusion, and bulk diffusion. The lesson also explains the concept of effective permeability, which changes when a combination of viscous flow and Knudsen diffusion occurs. It further discusses the phenomenon of vapor diffusion through a pore, known as vapor pressure lowering. The lesson also introduces the concept of capillary condensation and how it affects the transport process. An example of this is the condensation of vapor molecules inside a pore, which follows a different transport mechanism than Fickian diffusion.

Video Highlights

01:40 - Understanding vapor diffusion through a pore
05:11 - Introduction to capillary condensation & adsorption isotherm
13:00 - Discussion on pore size distribution
23:16 - Understanding the Kelvin equation and capillary condensation

Key Takeaways

- Transport mechanisms in porous media include viscous flow, Knudsen diffusion, surface diffusion, and bulk diffusion.
- Effective permeability changes when a combination of viscous flow and Knudsen diffusion occurs.
- Vapor diffusion through a pore, known as vapor pressure lowering, is a unique phenomenon that occurs in porous media.
- Capillary condensation is a well-known phenomenon that occurs when attractive interaction between molecules overrules fluid wall interaction.
- The Kelvin equation helps predict at what pressure condensation is likely to occur in a pore of a certain size.