What is diffusion in porous media?

What is diffusion in porous media?

Introduction. Surface diffusion was originally introduced to study unusually large mass transfer rates of gases through porous media. It turned out that, besides the bulk diffusion in pores, particles can migrate across a foreign material along the pores surface.

Which refers to the movement of gas through porous material?

Porous media combustion (PMC), also known as filtration combustion, pertains to the heterogeneous interaction between two different media, usually a solid and a gas.

How does porosity affect diffusion?

When pore scale heterogeneity in the form of large pores is embedded, the tortuosity of porous media increases in comparison to those without large pores at the same total porosity, which indicates that heterogeneity slows down the diffusion process.

What is pore diffusion?

[′pȯr di‚fyü·zhən] (fluid mechanics) The movement of fluids (gas or liquid) into the interstices of porous solids or membranes; occurs in membrane separation, zeolite adsorption, dialysis, and reverse osmosis.

What is the movement and filtering of fluids through porous materials?

In fluid mechanics, fluid flow through porous media is the manner in which fluids behave when flowing through a porous medium, for example sponge or wood, or when filtering water using sand or another porous material.

What is Brinkman equation?

The Brinkman equation is a combination of linear momentum and mass conservation for the fluid in large pores and flow channels, and Darcy’s equation for regions with unresolved pores.

Is diffusion rate affected by pore size?

These results suggest that for small pores as in closely packed particle matrices of less than fine silt size, the rate of diffusion is significantly reduced. The observed diffusion hindrance effect was attributed to a viscous drag caused by the proximity of the pore wall.

What is external diffusion?

1. Mass transfer (diffusion) of the reactant(s) from the bulk fluid to the external surface of the catalyst pellet. 2. Diffusion of the reactant from the pore mouth through the catalyst pores to the immediate vicinity of the internal catalytic surface.

What is an Aerogel?

An aerogel is an open-celled, mesoporous, solid foam that is composed of a network of interconnected nanostructures and that exhibits a porosity (non-solid volume) of no less than 50%. The term “mesoporous” refers to a material that contains pores ranging from 2 to 50 nm in diameter.

What is configurational diffusion?

Configurational diffusion, also referred to as hindered or restricted diffusion, is when molecular sizes of diffusing fluids are appreciably larger than the pore opening resulting in denial of entry into such pores16,17,18. Configurational diffusion has been widely observed in varying kinds of porous media17,19,20,21.