Heat transfer coefficients were measured in fluidization columns of 0.29 m and 1.56 m ID at fixed distance above the distributor, using an identical vertical heater, the same alumina particles and geometrically scaled bubble-cap distributors. The magnitude of the maximum heat transfer coefficients was found to be unaffected by the column diameter, but occurred at higher superficial velocities in the larger column. When the local flow structure near the heater corresponded to the turbulent flow regime of fluidization, the local heat transfer coefficients were independent of radial position in both columns. (C) 2011 Elsevier B.V. All rights reserved.