Drying of Optically Semitransparent Materials by Combined Radiative-Convective Heating

The objective of this work has been to basically elucidate the drying characteristics of an optically semitransparent material by combined radiative and convective heating. The experiments were conducted for a graphite suspension, a slurry of surplus activated sludge and a wet silica sand. The time-change of the drying rate as well as of the surface temperature of the brimfully wet material layer were measured under the step heating conditions using an infrared lamp bundle and a blast of hot air heated by an electric heater. The experimental data obtained show satisfactory agreement with the calculated results from unsteady heat and mass transfer equations derived on the basis of a semitransparent drying model during the preheating and the constant drying rate periods.