The drying is the process of giving heat and a wind to the moist material containing liquids, a small amount of water and a solvent, evaporating a liquid, removing, and drying a product.

As a typical example, in the process decomposition of the solid drying.

The 1st step The moisture on the surface of the material evaporates.
The 2nd step The evaporated moisture passes through the gas boundary membrane which stood still of the solid surface and reaches the convection air.
The 3rd step The moisture transfer will continue until an equilibrium (to saturation) with the moisture in the air.
The 4th step The moisture of a material surface evaporates and it becomes thin.
The 5th step The moisture is diffused on the surface of the material from the material inside.
The 6th step Movement of the moisture will be stopped if the moisture in the air and the surface of the material becomes an equilibrium (if saturated).
The 7th step Movement of the moisture will be stopped if moisture of the surface and the inside becomes en equilibrium.

Related page:

1-9.How to expressions the constant drying period 1-7.Drying characteristic curve – Relation between a drying rate and moisture content 4-4.Drying speed and swept area of the hot air 1-2.The phase shift of the ustulation 3-1.Heat transfer and Mass transfer 1-4.Change of weight and the temperature by the drying 1-8.Why is the constant drying period. – Moisture movement in wet material. 1-5.Equilibrium moisture content and Critical moisture content – Influence of temperature and relative humidity