Transferencia

University of Technology
Chemical engineering department
Third year

Mass Transfer
By
Dr. Auroba .N.Abdullah

Mass Transfer Operations
Introduction:
What is chemical engineering?
Chemical engineering is the field of engineering that deals with industrial processes in which
raw materials are converted or separated into final useful products.
Who is the chemical Engineer?
Thefunction of a qualified chemical engineer is to apply chemistry of a particular industrial
process through the use of coordinated scientific and engineering principles. Also develop the
laboratory results of chemists into economical chemical plants, he must develop, design and
engineer both the complete industrial process and the equipment used in it. Then his duties can
be stated as:
1- He mustchoose the raw material.
2- He must design and operate the plant efficiently, safely, and economically.
3- He must know that his products meet the requirements set by the customers.
4- When science does not give him a complete answer, he must use experience & judgment
to combine all sources of information to reach particular solution to processing problems.

Definition of Unit Operation:Thephysical operations necessary for manufacturing chemicals deals mainly with the
transfer and change of material and energy principles by physical means but also by
chemical – physical means such as mass transfer, heat transfer and momentum transfer (fluid
dynamics). There are two types of unit operation classifications:
The first one depends on the process type as:
1- Processes without chemicalreaction, as distillation, crystallization, absorption,
extraction, and filtration.
2- Processes with chemical reactions as nitration, oxidation, and sulfonation.
While the second classification depends on the type of transfer occur within the process such as:

1- Mass transfer operations
Transfer of component from one phase to another such processes is:
Gas absorption, Distillation,Extraction, Crystallization, Drying, Evaporation, Leaching,
Stripping, Mechanical separation for example (Filtration, settling, size reduction, and
sedimentation).

2- Heat transfer operations
Accumulation and transfer of heat and energy such as:
Heat exchanger, Evaporation, Drying, Distillation.

3- Momentum transfer operations
Flow and transportation of fluid and solid such as:
Fluid flow,Mixing, Handling of solid, Fluid transportation.

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Chapter Two
Mass Transfer & Diffusion
Mass transfer is the net movement of a component in a mixture from one location to
another location where the component exists at a different concentration. Often, the
transfer takes place between two phases across an interface. Thus, the absorption by a
liquid of a solute from a gas involves masstransfer of the solute through the gas to the
gas-liquid interface, across the interface, and into the liquid. Mass transfer models are
used to describe processes such as the passage of a species through a gas to the outer
surface of a porous adsorbent particle and into the pores of the adsorbent, where the
species is adsorbed on the porous surface. Mass transfer is also the selectivepermeation through a nonporous polymeric material of a component of a gas mixture.
Mass transfer is not the flow of a fluid through a pipe. However, mass transfer might
be superimposed on that flow. Mass transfer is not the flow of solids on a conveyor
belt.
Mass transfer occurs by two basic mechanisms:
(1) Molecular diffusion by random and spontaneous microscopic movement of
individual moleculesin a gas, liquid, or solid as a result of thermal motion; and
(2) Eddy (turbulent) diffusion by random macroscopic fluid motion.
Molecular and/or eddy diffusion frequently involves the movement of different
species in opposing directions. When a net flow occurs in one of these directions, the
total rate of mass transfer of individual species is increased or decreased by this bulk
flow or...