A small cold model was employed to investigate the heat-transfer mechanism for a new fluidized catalyst cooler. Local heat-transfer coefficients (h) and tube surface hydrodynamics were systematically measured by a specially designed heat tube and an optical fiber probe. The higher total h further validated the feasibility of the heat transfer intensification method used in the new catalyst cooler, which indicated that the induced higher packet renewal frequency due to the nonuniform gas distribution played a dominant role in its increased hs. Strongest heat transfer intensification effect was located at r/R-w>0.8 below the heat transfer intensification height. The changes of the mean packet residence time in the radial and axial directions and with superficial gas velocity were all agreeable with the measured hs according to the packet renewal theory. This further demonstrated the feasibility of the experimental method for tube surface hydrodynamics. (c) 2015 American Institute of Chemical Engineers AIChE J, 61: 2415-2427, 2015