PARTICLE-SIZE EFFECT IN MICROWAVE-HEATING OF GRANULAR-MATERIALS

Heating and drying of granular Al2O3 and Fe3O4 particles by microwave energy (2.45 GHz, 500 W) are reported. The results show that drying of Al2O3 was influenced by both particle size and initial mositure content, whereas drying of Fe3O4 was independent of these two variables. However, heating was particle size dependent in both cases but the effect was opposite, viz., fine Al2O3 heated faster than coarse Al2O3, whereas coarse Fe3O4 heated faster than fine Fe3O4. Relevance of the results in practical applications is also discussed.