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Effect of orientation on heat and mass transfer in stacked beds of spheres

University of British Columbia

Heat, mass and momentum transfer rates have been measured in two stacked beds of porous spheres having equal fractional void volume but different orientation with respect to the direction of fluid flew. An air-water system was studied under essentially adiabatic conditions over a Reynolds number range 100-1200. Orientation had negligible effect on heat and mass transfer rates though considerable effect on friction factor. An explanation for this behaviour is presented in terms of a difference in the degree of turbulent wake formation for the two assemblages, similar to that observed in comparable banks of closely packed staggered and in-line heat exchanger tubes. The experimental results contradict simple analogies between momentum, heat and mass transfer which show a direct proportionality between total friction factor and heat and mass transfer factor. Measured friction factors were about 50% in excess of those obtained by Martin for similar assemblages of smooth metal spheres. This is explained by the higher surface roughness of the refractory-like spheres used in the present investigation.

Text

2012-02-07

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http://hdl.handle.net/2429/40524

Chemical and Biological Engineering

University of British Columbia

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