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