EFFECTS OF HIGH-FREQUENCY ELECTROMAGNETIC-FIELD ON HEAT-SENSITIVE MEDIA .1. FUNDAMENTALS, MODEL AND EXPERIMENTAL CONCEPTION

Microwave energy represents a volumetric heat source for dielectric materials. Materials of high dielelectric loss factor may be heated in a very short time by microwave radiation. Driving force for beating is the thermal gradient directing from inside of the material to outside. Simultaneous microwave and convective energy input provides favourable conditions for the process of drying. Drying of heat sensitive, gel-like materials of high moisture content requires exact knowledge of kinetics and reliable control of drying process. Authors demonstrate a pilot-plant equipment developed for this purpose. A physical-mathematical model was compiled for description of heat and mass transfer. The model was adapted for two different cases, drying of the gelatin film and the polyacrylamide sphere.