Mass Transfer

MOLECULAR DISCUSION
JOCUSSING ON DISCUSION CAUSED BY THE PRESENCE OS A CONCENTRATION GRADIENT




LAOSW
DISCUSION -
CA =
CONCENTRATION GRADIENT

->
CONSTANT P ↓

↳Da dCA DAB= DISCUSION COESICIENT
->
CONSTANT T

-- CA =
CONCENTRATION OS A


dZ


C
z DISTANCE TRAVELLED
=




IXA= CONCENTRATION GRADIENT
MORE STRICTLY :
↓

-Day
CT= TOTAL CONCENTRATION

XA= MOLE GRACTION OS A




⑰DEFINITIONS



= =
GAS PHASE


AVERAGE VELOCITIES
MOLAR
MASS AVERAGE VELOCITY : MOLAR AVERAGE MASS



⑮
Vi
W
Umol =-
[CiVi
C


JLUXES
-




->
NA= GLUX DESINED WITH RESERENCE TO CIXED COORDINATES


->
JA =
GLUX DESINED WITH RECERENCE TO COORDINATES MOVING WITH AVERAGE VELOCITY




ISOTHERMAL ,
ISOBARIC SYSTEM :




I
EABYCA
DAB
-
SAMe
= -
~
16 C IS CONSTANT :


DA
I
NON-ISOTH-IRMAL ,
ISOBARIC SYSTEM :



EECDAB

, MASS TRANSPORT EQUATION
CONCENTRATION
BULK CLOW GRADIENT
COMPONENT COMPONENT




+NB) Ni-e
- -


De Xa
-




BINARY SYSTEM MULTI-COMPONENT SYSTEM


-> NOBUL SLOW : NATNB =0 :
W
NA=-D 0Z

-> DILUTE MIXTURE (i . e . MOST VAPOURS IN AIR) :


XAC1 AND CA +
STATIONARYI
->
STAGNANT B
:


NB
=
0 ..
A-D
NA(1 XA) -
=
-

x


↳NA=
-> USE COR INTEGRATION