The heat and mass transfer characteristics of boiling point drying using radio frequency and microwave electromagnetic fields

Abstract A physical model is presented to describe the drying of unbound, pendular moisture, by a method utilising the volumetric absorption of electromagnetic energy generated at radio or microwave frequencies. The model deals with those cases where the temperature of the wet solid can be quickly raised to the boiling point of the liquid. Evaporation takes place within the pores and gives rise to an increase in pressure which drives out the vapour. Using simplified heat and mass transfer equations, the initial heating, the pressure generation and the drying of the solid are related to the properties of the wet material.