Environmental Engineering Reference
In-Depth Information
B.3
Mass transfer correlations
[Excerpts from:
Diffusion: Mass Transfer in Fluid Systems
, E. L. Cussler, Cambridge
University Press, 1997]
B.3.1
Fluid-solid and fluid-fluid interactions (see Table B.1)
B.3.2
Fluid-column packings
These correlations are based on data for the following column packings:
Raschig rings:
1
/
4
to 2 inches
Berl saddles:
1
/
2
to 1
1
/
2
inches
Pall rings: 1 inch
Spheres:
1
/
2
and 1 inch
Rods:
1
/
2
and 1 inch
k
L
1
/
3
0051
G
L
a
w
µ
L
2
/
3
−
1
/
2
ρ
L
µ
L
g
µ
L
ρ
L
D
L
(
a
v
D
p
)
0
.
4
=
.
.
Liquid phase:
0
C
1
0
.
7
1
/
3
k
G
RT
a
v
D
G
=
G
G
a
v
µ
G
µ
G
ρ
G
D
G
(
a
v
D
p
)
−
2
.
0
Gas phase:
.
a
w
µ
L
)of4
to 400 for water and 1 to 40 for organic absorbents. For
k
G
, the gas Reynolds number
(
G
G
/
The range of data for
k
L
extended from a liquid Reynolds number (
G
L
/
a
v
µ
G
) ranged from 5 to 1000. For the packing:
exp
0
.
2
0
.
75
G
L
a
v
µ
L
0
.
1
G
L
a
v
ρ
−
0
.
05
45
σ
c
σ
a
wet
a
v
=
G
L
ρ
L
σ
1
−
−
1
.
×
,
L
g
a
v
specific surface area of packing, (m
2
m
3
)
where
a
v
=
/
specific surface area of wetted packing, (m
2
m
3
)
a
wet
=
/
5.23 for packing larger than
1
/
2
inch;
C
1
=
dimensionless constant.
C
1
=
2.0 for packing less than
1
/
2
inch
C
1
=
liquid-phase diffusion coefficient, (m
2
D
L
=
/
s)
D
p
=
nominal packing size, (m)
gas-phase diffusion coefficient, (m
2
D
G
=
/
s)
s
2
)
g
=
acceleration of gravity, (9.81 m
/
m
2
)
G
L
=
liquid-phase mass velocity, (kg
/
s
·
m
2
)
G
G
=
gas-phase mass velocity, (kg
/
s
·
m
2
)
k
G
=
individual gas-phase mass transfer coefficient, (mol
/
s
·
m
2
)
k
L
=
individual liquid-phase mass transfer coefficient, (mol
/
s
·
µ
L
=
liquid viscosity, (kg
/
m
·
s)
µ
G
=
gas viscosity, (kg
/
m
·
s)
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