Drying Process
o The drying process involves a simultaneous heat and
mass transfer from and to the drying medium as
well as biological and chemical reactions
o Heat required for evaporation of the moisture is
transferred from the drying air to the product to be dried
by convection, conduction and radiation
o Heat is transferred from the surface to the interior of
the product by conduction
o Vapour is transferred from the interior to the surface
by diffusion or capillary flow
o Drying air absorbs the evaporated moisture and
removes it from the product
For the drying of agricultural products air is used as drying
medium and the heat is transferred by convection
Heat Transfer
o Drying process is initiated by