A Fundamental Study of Fluidization and Heat Transfer Characteristics around a Horizontal Heated Circular Cylinder Immersed in a Fluidized Bed

Abstract

The fluidization and heat transfer chracteristics around a single horizontal heated circular cylinder immersed in a fluidized bed are fundamentally studied in this paper to elucidate the mechanism of heat transfer augmentation in a fluidized bed heat exchanger. The state of fluidization of p. articles is observed for various fluidization velocities covering fixed and fluidized beds. Further-more, the fluctuating pressure and the local heat transfer coefficient around the cylinder are measured. The fluidization patterns of the bed of the fixed, bubbling, slugging and turbulent states correspond to the fluctuating pressure around the cylinder. The local behavior of p. articles near the cylinder surface are classified into three categories : (1) the still region, ( 2 ) the sliding region and ( 3 ) the mixing region. The position where the maximum local heat transfer coefficient takes p. lace is located nearly on the boundary between the sliding and mixing regions and moves toward the rear side along with the boundary with an increase of fluidization velocity.