Bed-to-wall heat transfer properties of a vertical heat tube in a fluidized bed of fine fluid catalytic cracking (FCC) particles are measured systematically using a specially designed heat tube. Two important surface hydrodynamic parameters, i.e. the packet fraction (d pa ) and mean packet residence time (s pa ) based on the packet renewal theory, are determined by an optical fiber probe and a data processing method. The experimental results successfully reveal the axial and radial profiles of heat-transfer coefficient, the effects of superficial gas velocity, and static bed height on heat-transfer coefficient, most of which can be explained successfully by the measured s pa , an indicator of packet renewal frequency. s pa is found to play a more dominant role than d pa on bed-to-wall heat transfer. With a fitted correction factor, the modified Mickley and Fairbanks model is able to predict the heat-transfer coefficients with enough accuracy based on the determined packet parameters. Figure 23. Effect of static bed height on heat-transfer coefficients.