Convective currents induced by chemical reactions in partially-filled porous media

✍ Scribed by L.M. Pismen

• Book ID: 103002732
• Publisher: Elsevier Science
• Year: 1976
• Tongue: English
• Weight: 711 KB
• Volume: 31
• Category: Article
• ISSN: 0009-2509
• DOI: 10.1016/0009-2509(76)87012-1

✦ Synopsis

Concentration gradients in a partially liquid-tilled (unsaturated) porous body induce countercurrent gas and liquid flows which in their turn greatly influence the rate of the reactant transport. The origin of these convective flows is demonstrated starting with an elementary capillary circuit and passing to regular and random partially-filled porous media. The equations describing the mass transfer, reaction and balance of the pore filling in an unsaturated porous body are formulated and analysed. The qualitative estimates show that the gas-phase diffusion may play major role in smoothing out concentration gradients in a reacting liquid, and that under usual conditions the capillary forces in an unsaturated porous body with a wide distribution of pore sizes are strong enough to maintain the uniform hlhng throughout the partially-filled catalytic pellet. As an example of the quantitative solution of the basic set of equations, a simple reaction in a volatile liquid is considered; the results obtained show considerable acceleration of the diffusion-controlled reaction due to convective transport in an unsaturated porous medium.