Heat Transfer from an Immersed Tube in a Bubbling Fluidized Bed

Abstract

An Eulerian–Eulerian approach was used to investigate the effects of particle size and immersed tube temperature on bubbling and heat transfer behaviors in a gas fluidized bed. Large gas bubbles were observed to split into smaller bubbles that flowed around the immersed tube during the fluidization process. The formation of pockets of gas around the immersed tube led to a lower heat transfer coefficient. Heat transfer between the immersed tube and particles was facilitated by a phenomenon of particle renewal. Larger gas bubbles formed in the gas fluidized bed containing larger particles and this resulted in lower heat transfer coefficients due to the formation of more gas pockets around the immersed tube. When the temperature of the immersed tube was increased, the sensitivity of the heat transfer process toward formation of gas pockets around the immersed tube was observed to increase.