1992 Volume 18 Issue 5 Pages 600-606
The local and the average heat transfer coefficients between gas and solid particles in a circulating fluidized bed were estimated by temperature profiles by use of the heat balance equation. Characteristics of interfacial heat transfer were studied on an experimental basis.
The local heat transfer coefficient showed high value near the bottom of the riser. Above this elevation the local heat transfer coefficient gradually decreased to a constant value. The coefficient is influenced by a change in slip velocity between gas and solid particles. The average heat transfer coefficient was well correlated with the particle Reynolds number with slip velocity. The Nusselt number obtained in the circulating fluidized bed condition was low comparing with that in the pneumatic conveying and bubbling fluidized bed conditions. The Nusselt number decreased with an increase in total particle hold -up in the riser. These results suggest that heat transfer between gas and solid particles in the circulating fluidized bed condition depends on the solid particle behavior and gas flow characteristics.
