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Proceedings of CHT-08 ICHMT International Symposium on Advances in Computational Heat Transfer
May, 11-16, 2008, Marrakesh, Morocco

DOI: 10.1615/ICHMT.2008.CHT


ISBN Print: 978-1-56700-253-9

ISSN: 2578-5486

NUMERICAL INVESTIGATION OF HEAT TRANSFER IN A TALL ENCLOSURES WITH RIBBING WALLS

page 14
DOI: 10.1615/ICHMT.2008.CHT.1020
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RÉSUMÉ

The aim of the present work was to numerically study flow and heat transfer in a vertical rectangular cavity with high-aspect-ratio H/L = 10. The vertical and horizontal walls were assumed isothermal and adiabatic, respectively. The main purpose was to examine the effect of sidewall ribbing (rib height and number of ribs) on the coefficient of heat transfer across the cavity. The number of ribs was 0 to 40, and the rib height was l/L = 0 ÷ 0.4. The fins, arranged either in staggered or opposing order, were attached to the cold as well to the warm wall.
Two types of ribs, perfectly conducting ribs and adiabatic ribs, were analyzed. The range Rayleigh numbers Ra = 103-105 was include both the regime of thermal conduction and the multi-cell convection regime. Full two-dimensional Navier-Stokes equations in the “stream function -vorticity” variables were solved.
The purpose of the present study was to numerically examine heat transfer at various Rayleigh numbers in vertical cavities with adiabatic or heat-conducting fins attached to both walls with varied fin length and inter-fin spacing.
The calculations showed that, for all rib heights examined, the surface-average heat-transfer coefficient first increases, attains a maximum, and then decreases with increasing number of ribs. The most pronounced heat-transfer intensification is observed for high ribs. No heat transfer suppression for perfectly conducting ribs was found; for adiabatic ribs, the heat-transfer rate decreases by 30% compared to its value for sidewalls without ribbing. This decrease is observed for small-height ribbing l/L ≈ 0.25 with rather a small (comparable with the cavity width) rib-to-rib spacing.

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