Annals of the Assembly for International Heat Transfer Conference 13

ISBN 1-56700-225-0 / CD 1-56700-226-9

Year 2006

M. Kristoffersen
University of Minnesota, Minneapolis, USA

F. A. Kulacki
Department of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, USA

Experiments are reported that characterize the nature of the flow and heat transfer that occur at high Rayleigh number in a porous medium heated from below by a constant heat flux. A porous medium with the solid phase consisting of randomly stacked 6 mm DIA soda lime-silicate spheres (ε ∼ 0.37) and water as the fluid phase is contained in a test cylinder with a diameter-to-height ratio of 0.526, insulated wall, and isothermal top. The heated surface and fluid temperatures at different radial and axial locations are monitored for ∼10⁵ s to obtain mean fluctuating temperatures well into the regime of steady overall heat transfer. Measurements above the heated surface indicate the existence of upwelling thermal bursts along the centerline. The magnitude and frequency of temperature fluctuations increases with increasing Rayleigh number. Temperature fluctuations are greatest near the centerline of the test cell and decrease with radius.

PRT-06 pages DOI: 10.1615/IHTC13.p5.60 Download article

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