Mechanism of radiative heat transfer between fluidizing particles and a cooled surface in a fluidized bed

We experimentally investigated the radiation heat transfer occurring in a gas-solid fluidized bed between the fluidizing particles and a cooled heat transfer surface. To evaluate this heat transfer, radiation emitted from fluidizing particles to the cooled surface was measured using an infrared (IR) camera, which is located external to the bed so as not to disturb the bed fluidization. By doing this, the cooled surface was made of transparent CaF ₂, and was cooled by air convection. Our results revealed that there exist cooled fluidizing particles adjacent to the surface and they suppress the radiation heat transfer between the surface and high temperature fluidizing particles in the depth of the bed. In addition, the effects of the fluidizing velocities, the radiative characteristics, and the particle diameter on the radiation transfer were clarified.