Direct-contact heat exchange between fluidizing particles and a heat transfer surface in a fluidized bed: Temperature visualization of fluidizing particles

Heat conduction during contact between a heat transfer surface and fluidizing particles, a phenomenon which is one of the effective heat transfer mechanisms in a gas-solid fluidized bed, has been empirically investigated. The temperature profile of the fluidizing particles during the contact period is visualized with the aid of an infrared imager. The visualization reveals that the particles have been considerably heated in the thermal boundary layer on the heat transfer surface before contact. Based on the visualized temperature profile of the particles, the contact conductance between a fluidizing particle and the heat transfer surface is estimated by an in inverse analysis. Using the evaluated contact conductance, the contributions of the conductive heat transfer to the total heat transfer are also evaluated.