Mass transfer to reacting laminar films
type: CreativeWork
description: The problem of predicting the rate of absorption for a solute gas which reacts with a non-volatile substance in the liquid film was first discussed just over half a century ago. The first case considered was that of instantaneous reaction and the solution was obtained using the comparatively simple interpretation of the Whitman "Two-Film Theory" Subsequently, progressively more difficult forms of this problem have been considered, involving reactions of various orders. Solutions for such cases have been developed using both the film theory and also the more sophisticated "Surface Renewal Theory". However, these theories are essentially concerned with transfer to stagnant pools or to deep films in plug flow. They have no terms which represent the effect of variable sub-surface velocity perpendicular to the direction of transfer. The best-known system with such velocity gradients is the thin film of Newtonian liquid, which exhibits a parabolic velocity profile between the free surface and the supporting plate. Solutions for transfer to thin Newtonian films have previously been obtained for absorption without reaction and for absorption with first order reaction. However, solutions have not previously been available for transfer to these films accompanied by instantaneous reaction. In this case a further complication arises in the form of discontinuity of concentration gradients at the reaction front. If numerical methods are employed, the effect of such discontinuity must be carefully evaluated, or serious errors may be generated. The primary aim of this research has been to develop a numerical procedure which accommodates the discontinuity at the reaction front. This has been achieved, and numerical solutions have been computed for a wide range of parameters. Their accuracy has been confirmed by comparison with analytical solutions which are known for certain limiting cases. A further aim has been to measure the absorption rate of carbon dioxide during extended expos…
abstract: The problem of predicting the rate of absorption for a solute gas which reacts with a non-volatile substance in the liquid film was first discussed just over half a century ago. The first case considered was that of instantaneous reaction and the solution was obtained using the comparatively simple interpretation of the Whitman "Two-Film Theory" Subsequently, progressively more difficult forms of this problem have been considered, involving reactions of various orders. Solutions for such cases have been developed using both the film theory and also the more sophisticated "Surface Renewal Theory". However, these theories are essentially concerned with transfer to stagnant pools or to deep films in plug flow. They have no terms which represent the effect of variable sub-surface velocity perpendicular to the direction of transfer. The best-known system with such velocity gradients is the thin film of Newtonian liquid, which exhibits a parabolic velocity profile between the free surface and the supporting plate. Solutions for transfer to thin Newtonian films have previously been obtained for absorption without reaction and for absorption with first order reaction. However, solutions have not previously been available for transfer to these films accompanied by instantaneous reaction. In this case a further complication arises in the form of discontinuity of concentration gradients at the reaction front. If numerical methods are employed, the effect of such discontinuity must be carefully evaluated, or serious errors may be generated. The primary aim of this research has been to develop a numerical procedure which accommodates the discontinuity at the reaction front. This has been achieved, and numerical solutions have been computed for a wide range of parameters. Their accuracy has been confirmed by comparison with analytical solutions which are known for certain limiting cases. A further aim has been to measure the absorption rate of carbon dioxide during extended expos…
author: Edwards, J. V.
language: eng
date published: 1979-11
date modified: 2026-07-24T04:39:25Z
provider: University of South Wales
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Polytechnic of Wales