Gas–solid fluidized beds have been widely used in heat transfer processes, and so there have been many studies focused on increasing heat transfer in such units. In the present work, a pilot scale cold mode experimental rig was constructed to assess the effects of hydrodynamics on bed-to-wall heat transfer and to investigate various means of enhancing heat transfer in a dense gas–solid fluidized bed with external solid circulation. The experimental results show that heat transfer in the dense region played a dominant role in total bed-to-wall heat transfer, accounting for more than 88% of the total heat transfer load. Heat transfer could be lowered as a result of solids bypass that occurred because of external solids circulation, but this effect was weakened by the radial mixing of particles. The heat transfer characteristics identified in this study indicate that a specially designed baffle can be used to enhance bed-to-wall heat transfer. After installing such baffles in the fluidized bed test structure, a 70% increase in the total heat transfer coefficient was obtained.

气固流化床已广泛用于传热过程中，因此有许多研究致力于增加此类装置的传热。在目前的工作中，建造了一个中试规模的冷模式实验装置，以评估流体动力学对床到墙传热的影响，并研究各种在外部固体循环的稠密气固流化床中增强传热的方法。实验结果表明，在稠密区域内的传热在床到壁的总传热中起着主导作用，占总传热负荷的88％以上。由于外部固体循环而发生固体旁路，因此可以降低热传递，但是这种影响由于颗粒的径向混合而减弱。在这项研究中确定的传热特性表明，可以使用专门设计的挡板来增强床对墙的传热。在流化床测试结构中安装此类挡板后，总传热系数增加了70％。