Bubble formation in gas fluidized beds

The investigations of Davidson et al. (D7) enable a theoretical analysis of the phenomenon of bubble formation in fluidized beds. They found that, 

The authors (B5) report that for flow rates between 50 and 250 cm3/sec, the bubble frequency remains essentially constant at 22 bubbles per second, whereas at lower flow rates, the frequency shows a marked tendency to rise. 

A more thorough experimental investigation was carried out by Harrison and Leung (H3). 

The bed depth has no influence on the size of the bubble produced. This indicates that the bubbles are foxmed under either constant flow or constant pressure conditions. In the intermediate region, Padmavathy, Kumar, and Kuloor (PI) have shown that the bubble volume in an air-water system is highly sensitive to the variation in the depth of the liquid column above the bubble forming nozzle. As the bed has no surface tension, no variation of flow is expected during bubble formation, and the conditions of constant flow are approximated. This explanation is due to present authors. 

The particle size of the solids does not influence the bubble size. 

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