AN EXPERIMENTAL STUDY OF THE DRYING OF GRANULAR MATERIALS IN A PACKED BED PASSED BY HOT AIR. THE LOCAL TEMPERATURE OF THE THERMAL AGENT

摘要

The experimental study of drying granular materials in packed bed passed by a gaseous thermal agent has been completed by the measurement of local temperature for the thermal agent at the exit from the bed. The determinations have been done under the same conditions with the measurements for the local humidity of solid: ceramic porous spheres with an 18 mm diameter and drying with air at two different temperatures, of 70℃ and 95℃. The drying, in nonsteady regime, has been resumed for three beds with different heights. The results obtained in the form of radial distributions for the thermal agent temperature confirm that the drying follows a zonal model and the existence of three zones in bed, each of them in another stage of the global process of drying granular bed, is possible,