HEAT-TRANSFER IN SHALLOW VIBRATED BEDS

Coefficients are reported for transfer of heat from a horizontal cylin der and from vertical, flat surfaces (paired back-to-back, closely spa ced-apart) to 30-mm deep vibrated beds (25 Hz) of alumina spheres and high- and low-density glass beads (at sizes from 63 to 707 mu m). In g eneral, the flat surfaces afford higher coefficients, but heat transfe r is sensitive to pattern and vigor of powder circulation. No broadly general explanation or correlation of vibrated-bed heat transfer can b e given; but the body of data provides leads for the engineer wishing to develop a vibrated-bed heat-exchanger design for non-sticky particu late matter. The leads hold promise of coefficients beyond 500 W/m(2) K, even perhaps approaching 1000. (C) 1998 Elsevier Science S.A. All r ights reserved.