Review on heat transfer in gas solid fluidized beds

Abstract

This review covers those aspects of heat transfer in fluidized beds related to bed/immersed tubes and bed/vessel walls heat transfer coefficients correlations. These correlations generally incorpo-rated the effects of operating conditions, bed and gas thermophysical properties and bed size and geometry. Experimental as well as empirical dimensionless models are presented. The general tendency in the literature is towards building up more realistic hydrodynamic models which incorporate particle and gas convective heat transfer components, solids residence time and local bubble behaviour at immersed surfaces. It is also generally recognized in the literature that heat transfer cannot be satisfactorily explained on the basis of stationery models but rather on the basis of unsteady state heat conduction models of solids movement induced by rising bubbles. The aspects of research mostly overlooked in the surveyed investigations were those related to inter phase heat transfer and the effect of operation under elevated temperatures and pressures.