Mass transfer is the net movement of mass from one location, usually meaning stream, phase, fraction or component, to another. Mass transfer occurs in many processes, such as absorption, evaporation, adsorption, drying, precipitation, membrane filtration, and distillation. Mass transfer is used by different scientific disciplines for different processes and mechanisms. The phrase is commonly used in engineering for physical processes that involve diffusive and convective transport of chemical species within physical systems.

Also Read : Modes Of Heat Transfer

Mass Transfer is a Unit Operation which itself is sub-divided into several operation like

1)Diffusion-Concentration Difference


3)Distillation-Temp. Difference and Conc. Difference



mass transfer

The common examples of mass transfer in our everyday life and in many industries are:

Also Read : Modes Of Heat Transfer

-diffusion of smoke discharged by tall chimney into the atmosphere,

-a drop of ink diffusing in a glass of still water,

-evaporation of a drop of perfume in a room,

-humidification of air flowing over a spray pond or cooling tower,

-mixing of diesel or petrol with air inside an internal combustion engine,

-diffusion welding of metals,

-diffusion of neutron in a nuclear reactor.

There are basically two modes of mass transfer: