FOG FORMATION AND DEPOSITION WITHIN LAMINAR AND TURBULENT NATURAL CONVECTION BOUNDARY LAYERS ALONG COLD VERTICAL PLATES

The formation of fog in laminar and turbulent natural convection boundary layers over a cold vertical surface is investigated theoretically under conditions of local equilibrium, using the similarity forms of the boundary layer equations. The ambient medium surrounding the surface is composed of a n...

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Bibliographic Details
Published in:Chemical engineering communications 1992-11, Vol.118 (1), p.163-187
Main Authors: EPSTEIN, M., HAUSER, G.M., FAUSKE, H.K., GROLMES, M.A., HENRY, R.E., LEUNG, J.C.
Format: Article
Language:English
Subjects:
Applied sciences
Cryogenics
Cryosurface
Energy
Energy. Thermal use of fuels
Exact sciences and technology
Fog formation
Frost buildup
Natural convection
Refrigerating engineering. Cryogenics. Food conservation
Thermophoresis
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Summary:The formation of fog in laminar and turbulent natural convection boundary layers over a cold vertical surface is investigated theoretically under conditions of local equilibrium, using the similarity forms of the boundary layer equations. The ambient medium surrounding the surface is composed of a noncondensable and a condensable vapor component which is present in trace amounts. The deposition of the vapor species in laminar convection over the cold surface is assumed to occur via ordinary Fick diffusion of vapor plus thermophoretic fog particle drift. In turbulent flow these transport mechanisms are reinforced by the eddy diffusion of vapor and fog particles. Turbulence is shown to lead to a discontinuity in the fog concentration at the boundary between the fog and clear regions. Partial agreement is obtained with available data on frost formation on a vertical plate cooled to cryogenic temperatures by assuming that the thermophoretic transport coefficient is about one order-of-magnitude smaller than its theoretical upper limit.
ISSN:0098-6445
1563-5201
DOI:10.1080/00986449208936092