Drying Characteristics of Gelatinous Materials Irradiated by Infrared Radiation

As a food model for infrared drying, a gelatinous bed composed with agar-gel and powder was used. To study the influences of the bed conditions, the emissivity of the powder materials and their initial-volume fractions were considered. To study the influence of the radiative heat source, the spectral distribution of irradiation power was examined. We selected three kinds and several initial-volume fractions of powders (alumina, silver and stainless steel) and used two types of infrared heaters (a far-infrared heater and a near-infrared heater). Infrared drying of the gelatinous bed was performed, and a heat transfer model for infrared drying of the gelatinous bed was constructed. The model-calculation results were compared with the experimental results, and agreed with the experimental results consistently for FIR drying and qualitatively for NIR drying. The present study shows a fundamental guideline on the application of infrared radiation to the drying operation.