Computational study on heat transfer and bed flow according to different regimes of fluidized beds

Abstract

This work presents a computational study to compare heat transfer processes and flow behavior of the bed among different regimes of fluidized bed reactors with fixed, bubbling, and slugging flow regimes. Sand particles with a mean diameter of 550 μm were used as a bed material fluidized by air. Wall-to-bed heat transfer and fluidization behavior were studied at different inlet velocities to represent different flow regimes. A two-phase model with kinetic theory of granular flow was used to simulate both heat transfer and flow characteristics. Simulation findings were validated by comparing them with available experimental results, in which there was good agreement. The obtained results demonstrated that the gas-solid heat transfer and wall-to-bed heat transfer processes strongly depend on the bed flow structure, especially void and solid volume fractions. Slugging beds related to the highest inlet velocity achieved the best conditions of a heat transfer process, as indicated by the highest gas-solid and wall-to-bed heat transfer coefficients. Simulation results also showed that slugging behavior had no negative effect on the heat transfer process despite problems such as obstruction and entrainment.