Effect of Axis Ratio on Heat Transfer From an Elliptic Cylinder Immersed in a Fluidized Bed

Abstract

Heat transfer characteristics around three elliptical cylinders with different axis ratio in a fluidized bed are experimentally studied. Air is used to fluidise 3 batches of different sizes of silica sand, of 500, 780 and 950 μm average diameter. The cylinder axes ratio AR (longitudinal axis / transverse axis) for the experimented cylinders are 1, 2, and 4. Behaviours of local Nusselt numbers as a function of cylinder's axis ratio around the tube surface are presented. The impact of Reynolds number, average particles size and cylinder's axis ratio on average Nusselt number are demonstrated. The results showed that for all cases the average rate of heat transfer improves with Reynolds number. For the same average particle size of the bed, the average rate of heat transfer improves with increasing axis ratios. The results also showed that for the same axis ratio, the average rate of heat transfer decreases with increasing the mean particles size. The experimental results of a cylinder with axis ratio= 1 is compared with another work and a good agreement is noticed