Post on 16-Nov-2014
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Transport Phenomena: Transport Phenomena: Mass TransferMass Transfer
(CAB 3033)(CAB 3033)
Instructor :Instructor : Dr. Nurul HasanDr. Nurul Hasan
Date :Date : 06/03/0906/03/09
Universiti Teknologi PETRONASUniversiti Teknologi PETRONAS
What we learn today?What we learn today?
•Fick’s Law of Binary Diffusion
•Non-dimensional number for diffusion
•T and P dependence: Diffusion
•Diffusion Theory: at low density
•Diffusion Theory: binary liquid
•Shell Balance: Mass Transfer
Continue….Continue….
Fick’s law of diffusion for binary mixtures
The basic equation for Fick’s law for an isobaric and isothermal is :
Which is diffusive molar flux along the y-dir.
dy
dwDJ AABA
Continue….Continue….
Fick’s law of diffusion for binary mixtures
The basic equation for Fick’s law for an isobaric and isothermal is :
Which is diffusive molar flux along the all three direction
AABA wDJ
Continue….Continue….
Fick’s law of diffusion for binary mixtures
The basic equation for Fick’s law for an isobaric and isothermal is :
Which is diffusive molar flux along the all three direction
BBAB wDJ
Non-dimensional Number
k
C p ˆ
Pr
ABAB DDSc
•Prandle number
•Schimdt number
•Lewis numberABpAB DC
k
DLe
ˆ
T & P Dependence: Diffusion
•Liquid: increases with T
•Gas: Increases with T,
•Gas: decreases with P
•Liquid: P does not have any effect
Diffusivity: TheoryDiffusivity: Theory
•Example 17.3-1: At low density
•Example 17.4-1: Binary liquid
•Section 17.5: colloidal suspensions
Shell Balance: M TransferShell Balance: M Transfer
onAccumalati
production
mass of rate
out mass
of Rate
in mass
of Rate
Shell Balance: M TransferShell Balance: M Transfer
•Take a shell (volume)
•Divide by some parameters
•Take Limit PDE
•Fick’s Law
•Integrate and apply Boundary conditions
•Concentration of species