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ISSN Online: 2377-424X

ISBN Print: 0-89116-130-9

International Heat Transfer Conference 6
August, 7-11, 1978, Toronto, Canada

THE ONEWAY HEAT WALL − ANALYSIS AND EXPERIMENTS ON A VERTICAL STACK OF INCLINED CAVITIES

Get access (open in a dialog) DOI: 10.1615/IHTC6.2230
pages 119-124

Résumé

Experimental results indicate that walls about a foot thick can be designed to conduct heat an order of magnitude more readily one way than another. These first tests are crude.

Earlier, a series of experiments had shown a ratio as high as a million to one between natural convection in perfectly insulated tubes inclined a few degrees upward, and in tubes inclined a few degrees downward. However, when a wall is constructed of cavities, the end effects and conduction between cavities bring the ratio down to a value more like ten.

Analytical results are also reported. These, based on two-dimensional, finite-difference calculations, predict roughly the heat conductance values observed. They also show the flow patterns, with unexpected features for the upwardly inclined stacked cavities; with finite cross conductance, and large Rayleigh numbers, multiple-eddy flows develop, and under some conditions these flows become oscillatory.

It appears feasible to build walls, or sides of large containers, that will maintain interiors either cooler or hotter than the average exterior temperature.