3. Kinetic analysis

In the case of many hygroscopic, porous, mineral, food or biological materials, conventional analysis of drying kinetics based on the various periods identified according to speed (constant, decreasing...) can only, very partially, reflect the physical stages and phenomena of drying.

Often, the internal diffusion of water within the porous material is considered to be the essential process limiting and, therefore, translating the drying operation.

• However, this assumption should only be adopted after it has been ascertained that :

  • external transfers are by no means limiting processes; for example, an air flow at high speed, low humidity and high enough temperature is required for these transfers to be much more kinetic than internal processes;

  • ...