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ISSN Online: 2377-424X

ISBN CD: 1-56700-226-9

ISBN Online: 1-56700-225-0

International Heat Transfer Conference 13
August, 13-18, 2006, Sydney, Australia

FORCED CONVECTION HEAT TRANSFER FROM WALL SURFACE IN PACKED BEDS AT HIGH REYNOLDS NUMBERS

Get access (open in a dialog) DOI: 10.1615/IHTC13.p20.10
12 pages

摘要

Turbulent forced convection heat transfer in packed beds is considered in the context of analogy with turbulent separated flows based on visual observations by various authors and available quantitative measurements of the velocity and pressure pulsation spectra and the near-wall zone velocity and temperature profiles in packed beds that fully correspond to those in turbulent separated flows. These facts give grounds to put forward the physical model based on the analogy of transfer processes in packed beds and near-wall zone of turbulent separated flows resulting in the fundamental limiting “two-third power law”
Nu = const Re2/3 Prm
Careful measurements of the heat transfer coefficients were conducted in the tube filled with spherical glass balls with diameters of 0.9, 3.2 and 8.9mm with water and aqueous glycerine solution as working liquids. The effective thermal conductivity was determined from experimental temperature profiles. It has been shown that for the turbulent filtration the contribution of near-wall thermal resistance in overall heat transfer coefficient could be as great as 90% and more. Experimental values of the wall heat transfer coefficient combined with the data on the one-layered packing in annular channel as a model of near-wall zone with minimum effect of core clearly support the physical model and the universality of heat transfer law for surfaces embedded in grainy layers. This conclusion is confirmed by a large body of data of various authors.