Summary "Mass transfer operations-Drying "

Mass Transfer Operations-I

Drying

, Drying
• Drying is the operation by which moisture is removed in
relatively small quantities from solids or solid like materials by
evaporation.
• Drying differs from evaporation operation in which water is
removed by vaporization from solutions

,Differences

, Drying equilibrium
• The moisture contained in a wet solid or liquid solution exerts
a vapor pressure to an extent depending upon the nature of
the moisture, the nature of the solid, and the temperature.
• If a wet solid is exposed to a continuous supply of fresh gas
containing a fixed partial pressure of the vapor p, the solid will
either lose moisture by evaporation by evaporation or gain
moisture from the gas until the vapor pressure of the
moisture of the solid equals p.
• The solid and gas are then in equilibrium, and the moisture
content of the solid is termed its equilibrium moisture content
at the prevailing conditions.