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Numerical study of natural convection loss from open cavities

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Title Numerical study of natural convection loss from open cavities
 
Creator PRAKASH, M
KEDARE, SB
NAYAK, JK
 
Subject Open cavity
Natural convection loss
Nusselt number correlation
SHALLOW OPEN CAVITIES
HEAT-TRANSFER
MIXED CONVECTION
SOLAR RECEIVERS
TILTED CAVITY
DISH
FLOW
CONCENTRATOR
SURFACE
 
Description In this paper, the natural convection occurring from open cavities is analysed. Three different cavity shapes are studied namely cubical, spherical and hemispherical geometries having equal heat transfer area. The numerical analysis is performed on three dimensional (3-D) cavity models using the Fluent CFD software. The studies are performed for cavities having isothermal wall temperatures of 100 degrees C, 200 degrees C and 300 degrees C. The effect of opening ratios (d/D or a/H) of 1, 0.5 and 0.25 on the convective loss is studied for the cubical and hemispherical cavity shapes while the spherical cavity is analysed for opening ratios of 0.5 and 0.25. The effect of inclination of the cavity on the natural convection is studied for five inclinations; 0 degrees (aperture facing sideways), 30 degrees, 45 degrees, 60 degrees and 90 degrees (aperture facing vertically downwards). The natural convection loss is found to increase with an increase in opening ratio. The increase in natural convection loss for different inclinations is found to vary between 30% and 80% when the opening ratio is increased from 0.25 to 0.5 for all cavity shapes. A similar increase in natural convection loss is observed when the opening ratio is increased from 0.5 to 1 for the cubical and hemispherical cavities. The natural convection loss increases with increase in cavity wall temperature. A decrease in loss is observed with increase in cavity inclination; the highest convective loss being at 0 degrees inclination and the lowest at 90 degrees. For all the cavity shapes analysed with opening ratios of 0.5 and 0.25, it is observed that the hemispherical open cavity has the highest natural convection loss when compared to cubical and spherical cavities. The hemispherical cavity has higher convective loss than the cubical cavity for an opening ratio of 1. A Nusselt number correlation involving the effect of cavity shape, Rayleigh number, inclination angle and the opening ratio has been developed from this study. (C) 2011 Elsevier Masson SAS. All rights reserved.
 
Publisher ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER
 
Date 2014-10-15T12:52:13Z
2014-10-15T12:52:13Z
2012
 
Type Article
 
Identifier INTERNATIONAL JOURNAL OF THERMAL SCIENCES, 5123-30
http://dx.doi.org/10.1016/j.ijthermalsci.2011.08.012
http://dspace.library.iitb.ac.in/jspui/handle/100/14934
 
Language en