Heat transfer in directly irradiated fluidized beds

In the present study radiative heat transfer from a concentrated simulated solar radiation source to a fluidized bed is investigated by time-resolved infrared mapping of the bed surface temperature. A fluidized bed of silicon carbide particles (0.127 mm), whose cross-sectional area is 0.78 × 0.78 m, was directly irradiated by highly concentrated simulated solar radiation, emitted by a 4 kWel short-arc Xe lamp coupled with an elliptical reflector. The experimental apparatus is also equipped with a movable nozzle coupled with a bubble generation system located coaxially to the concentrated simulated solar beam. The interaction of the concentrated radiative flux with the fluidized particles moving under the action of bubble bursting was assessed by characterizing the time-resolved bed surface temperature as the fluidization gas velocity was varied. The effect of localized generation of bubbles was also investigated by injecting chains of multiple bubbles from the nozzle located at variable distance from the bed surface.