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ISSN Online: 2377-424X

International Heat Transfer Conference 12
August, 18-23, 2002, Grenoble, France

The Effect of Non-Uniform Wall Heat Generation on Natural Convective Flow in a Two Enclosure Arrangement Involving a High Aspect Ratio Side Enclosure Joined to a Large Square Enclosure

Get access (open in a dialog) DOI: 10.1615/IHTC12.1790
6 pages

Abstrakt

A numerical study of natural convective flow in a joined two-enclosure arrangement has been undertaken. In this arrangement, a heated wall kept at a uniform high temperature is contained in a high aspect ratio rectangular side enclosure. This enclosure is separated from a larger square enclosure by a dividing wall which is opposite to the heated wall and which is impermeable but offers no resistance to heat transfer and along which there is a linearly varying rate of heat generation. The wall of the main square enclosure that is opposite to the dividing wall between the enclosures is maintained at a uniform low temperature. All remaining walls in both enclosures are adiabatic. The situation considered is an approximate model of a window exposed to a hot outside environment and covered by a plane blind which, in turn, is exposed to cooled room. The heat generation in the dividing wall is then the result of solar radiation passing through the window glass and falling on the blind. In many such situations, due to the position of the sun and overhangs on the building, the heat generation rate is not uniform. Here the heat generation rate has been assumed to vary linearly from a maximum at the bottom of the blind to zero at the top of the blind. The flow has been assumed to be laminar and two-dimensional and fluid properties have been assumed constant except for the density change with temperature that gives rise to the buoyancy forces. The governing equations have been written in dimensionless form and the resultant dimensionless equations have been solved using a finite-element method. Results have been obtained for a Prandtl number of 0.7. The effects of Rayleigh number, dimensionless distance of the barrier (blind) from the hot surface, maximum dimensionless heat generation rate in the barrier and the dimensionless size of the heat wall section on the Nusselt number have been investigated. The results show that, as with a uniform barrier heat generation rate, a minimum occurs in the Nusselt number variation with dimensionless side enclosure width for a fixed Rayleigh number. The effect of the governing parameters on the value of the minimum Nusselt number and on the conditions under which it occurs have been investigated.