Similarity of transport processes in fluidized beds

The theory of similarity of heat and mass transfer processes in bubble flui dized beds is developed. It is based on the account for a main specific fea ture, which distinguishes a fluidized bed from other gas-solid systems, viz , a two-phase structure of the bed: the presence of bubble and emulsion pha ses. The existence of these phases determined the character of transport pr ocesses in the system in many respects and imparts a number of unique prope rties to the system that are widely used in engineering (isothermicity, hig h values of the coefficients of thermal conductivity and heat transfer, etc .). A system of dimensionless governing parameters which characterize local and integral similarity of fluidized beds is found. It is shown that Fr an d Ar numbers can serve as basic dimensionless characteristics of bubble and emulsion phases. The employment of these numbers makes it possible to obta in generalized relations for calculating transport characteristics of fluid ized beds which are distinguished by simplicity, physical and large univers al nature. (C) 1999 Elsevier Science Lid. All rights reserved.