Heat Transfer Mechanisms in a Gas – Liquid-Solid Fluidized Beds

Three-Phase Fluidized Beds have found an important place in processing technology as Reactors. Gas-Liquid-Solid fluidization is considered in the present paper as operating bed of fluidized solid particles simultaneously with co-current upward flow of a continuous liquid phase and a gaseous phase dispersed in the form of bubbles. In the present study, the experimental work of the author on heat transfer from the Wall-to-Bed ThreePhase Fluidization is described. The mechanistic models based on Double Thermal Resistance, Surface Renewal and Capillary Tube models are discussed and compared with the author data. After discussing the possible reasons for the discrepancy, a generalized correlation for the wall-to-bed heat transfer coefficient is developed. It was noted that the limitations of Semi-theoretical models and important conclusions are presented. A good understanding of heat transfer mechanism should further aid the design and optimization process.