Evaluation of heat transfer coefficient in gas–solid fluidized beds using cluster-based approach

The concept of temperature penetration depth is used to investigate the heat transfer behavior near the wall of fluidized beds, according to the cluster-based approach. The process of heat transfer through clusters which exist adjacent to the wall was viewed in context of partial and total heat penetration. In the case of partial heat penetration, the heat flux applied to the wall side of the clusters has not reached its bed-side, while in the case of total heat penetration the heat flux has completely crossed the cluster, and the temperature of its bed-side would differ from the bed temperature. Based on the heat balance equation inside the cluster, two different expressions were derived for heat transfer coefficient for each penetration period. The predictions of the proposed model are in close agreement with experimental values and to some extent better than existing models.