FACTORS INFLUENCING CONSTANT DRYING RATE OF WET GRANULAR BED IRRADIATED BY INFRARED RADIATION

The present study aims at gaining a good understanding of the mechanism of infrared radiation drying of a wet granular bed in the constant-rate period. Our attention was focussed on the factors influencing the constant drying rate of a granular bed irradiated by infrared radiation. As the variables, the conditions of the granular bed (emissivity of the powder materials and the particle size of the powders) and the radiative heat source (the spectral distribution of irradiation power) were examined. Infrared radiation drying of the granular bed was performed and the heat transfer model in the constant-rate period was studied. The constant drying rate was calculated by using the model. The calculated results were quantitatively compared with the experimental results, and agreed consistently with the latter by taking account of the spectral distribution of absorption of irradiation power by the granular bed.