Heat transport through the active layer of the moving bed in rotary drums

Abstract

The heat transfer at the freeboard surface of the solid bed was experimentally investigated in a batch rotary drum with a diameter of 0.6 m and a length of 0.45 m. The change of temperature at the surface and inside the bed was measured with Type-K thermocouples and an infrared camera. The thermocouples are specifically arranged at different radial distances from the inner wall. Experiments have been done with a variation of the operational conditions rotational speed from 1 to 6 rpm and filling degree from 5% to 15%. As test materials glass beads, quartz sand, steel spheres and expanded clay were used, whereas the impact of particle size and thermo-physical properties on the heat transport through free bed surface was analyzed. A characteristic effective thermal conductivity was defined for the active layer to represent the heat transport from the free bed surface.