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