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ADVANCED MASS TRANSFER
Amirkabir University of Technology
(Tehran Polytechnic)
Winter 2009
Chemical Engineering Department
By: Dr. Frazin Zokaee
By Dr. Zokaee
Course Outline:
CHAPTER 1: FLUX DEFINITION• Flux Definition
• Mass and Molar Transport by Convection
• Summary of Mass and Molar Fluxes
• Fick’s Law
CHAPTER 2: DIFFERENTIAL EQUATIONS OF MASS TRANSFER• Differential equation for mass transfer
• Boundary conditions
CHAPTER 3: MOLECULAR DIFFUSIVITIES• Diffusivities in Gases
• Diffusivities in Liquids
CHAPTER 4: MOLECULAR DIFFUSION
• Steady-State Molecular Diffusion
• Steady-State Equimolal Counter Diffusion in Gases
• Steady-State Unimolal Unidirectional Diffusion in Gases
• Molecular Diffusion in Liquids
• Diffusion through a Stagnant Gas Film
• Diffusion with a Moving Interface
• Diffusion through a Nonisothermal Spherical Film
• Diffusion with a Heterogeneous Chemical Reaction
• Diffusion with a Slow Heterogeneous Reaction
• Diffusion with a Homogeneous Chemical Reaction
• Unsteady-State Diffusion in a Sphere
• Unsteady-State Diffusion in a Slab
• Unsteady-State Diffusion in a Cylinder
By Dr. Zokaee
CHAPTER 5: MECHANISMS OF MASS TRANSFER
• The Two-Film Theory
• The Penetration Theory
• The Theory of Penetration with Random Surface Renewal
CHAPTER 6: MASS TRANSFER IN LAMINAR FLOW
• Mass Transfer in the Laminar Boundary Layer on a Flat Plate (Integral Solution)
• Mass Transfer in Laminar Natural Convection on a Vertical Plate
• Mass Transfer in a Falling Liquid Film in Laminar Flow
o Mass Transfer Between a Gas Phase and a Falling Liquid Film (Gas Absorption)
o Mass Transfer Between an Inclined Plate and a Falling Liquid Film(Solid Dissolution)
o Gas Absorption with Rapid Reaction
By Dr. Zokaee
CHAPTER 7: MASS TRANSFER IN TURBULENT FLOW
• Mass Transfer in the Turbulent Boundary Layer on a Flat Plate
• Mass Transfer in Turbulent Natural Convection on a Vertical Plate
• Mass Transfer Between an Inclined Plate and a Falling Liquid Film in Turbulent Flow
• Analogies Between Momentum, Heat and Mass Transfer
o Reynolds Analogy: Analogy Assuming Only a Turbulent Core
o Prandtl Analogy: Analogy Assuming a Laminar Sublayer and a Turbulent Core
o Von karman Analogy: Analogy Assuming a Laminar Sublayer, a Buffer Zone and a Turbulent Core
o Analogies in terms of j Factors
By Dr. Zokaee
Text Book
• R.B. Bird, W.E. Steward and E.N. Lightfoot, Transport Phenomena, 2nd Ed.,
John Wiley and Sons (2002).
• J. R. Welty, C. E. Wicks, R. E. Wilson and G. Rorrer, Fundamentals of
Momentum, Heat, and Mass Transfer, 4th Ed., John Wiley & Sons (2001).
•A. H. P. Skelland, Diffusional Mass Transfer, John Wiley and Sons (1974).
By Dr. Zokaee
What is Mass Transfer?
• The transport of one component from one place to another is called Mass Transfer.
Must have a mixture of two or more species for mass transfer to occur.
• Diffusional Mass Transfer involves the migration of one substance through another under the influence of a concentration gradient .
• Motion of molecular or fluid elements caused by some form of potential or driving force is called Mass Transfer.
By Dr. Zokaee
• Separation processes
Single phase
Between two phase
Direct contact
Indirect contact
Gas - Liquid
Gas - Solid
Liquid - Liquid
Liquid - Solid
– Absorption– Stripping
– Distillation
– Evaporation
– Humidification
– Dehumidification
– Adsorption
– Desorption
– Drying
– Sublimation
– Adsorption
– Desorption
– Leaching
– Crystallization
– Liquid-Liquid Extraction
Membrane separation
By Dr. Zokaee
• Types of Membrane
Porous membrane Dense membrane
– Solid diffusion
i i iP D
iP Permeability
By Dr. Zokaee
• Driving force in Membrane separation
Pressure gradient (∆P)
Concentration gradient (∆C)
Electric gradient (∆E)
Temperature gradient (∆T)
– Microfiltration
– Ultrafiltration
– Reverse Osmosis
– Nanofiltration
– Dialysis
– Pervaporation
– Gas Permeation
– Liquid Membrane
– Electro Dialysis (ED)
– Membrane Distillation
By Dr. Zokaee
• Mechanical Separation
Mechanical work and calculations are according the fluid flow in porous media and centrifugal force and etc.
– Mixing
– Size reduction
– Sedimentation
– Centrifugation
– Filtration
By Dr. Zokaee
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