Analysis of particle motion and heat transfer in circulating fluidized beds

In this study, the forces affecting the motion of particle clusters near the wall of a CFB were theoretically analysed. The motion trajectory and the contact time of clusters were determined from the proposed model for two cases, steel ball having density of 6980 kg m −3 and sand having density of 2500 kg m −3 . Computational results showed that the construction and operational parameters such as the bed equivalent diameter, the gas velocity and the bed temperature have great influence on the contact time of clusters. Based on analysis of the contact time of clusters, a theoretical model was developed for predicting the particle–gas convection heat transfer coefficient. The results were compared with experiments and were a quite agreement with the measured data in the open literature which suggests that the theoretical analysis conducted in this work can very well describe the convection heat transfer in a CFB. Copyright © 2004 John Wiley & Sons, Ltd.