Heat Transfer to Liquid/Solid Fluidized Beds in Cylindrical Pipes

Bed voidage and local heat transfer coefficients for liquid/solid fluidized beds in a cylindrical tube have been measured using water as liquid phase, and three sizes of cylindrical steel particles as well as glass, nickel, copper and lead spheres as solid phase. The independent variables included heat flux, liquid velocity and particle physical properties. Conclusive interpretation of the results was possible with the recently published model of Gibilaro et al. which was used to define the hydrodynamic behaviour of the fluidized beds. During particulate fluidization and in the transition zone, bed voidage and heat transfer coefficient are strongly dependent on particle size and particle density. Alternatively, bed voidage and heat transfer coefficient during aggregate fluidization are almost independent of particle size and particle density. The maximum heat transfer rate is observed at voidage of 0.7–0.75 which correspond to the point of maximum aggregation in the bed. The measured heat transfer coefficients are compared with published correlations.