Environmental Engineering Reference
In-Depth Information
L
µ
1
=
V
0
α
v
=
L
µ
1
=
α
V
0
=
average superficial fluid velocity.
It can be shown that:
2
2
zD
0
α
µ
2
=
µ
2
(
z
=
0)
+
V
0
2
2
LD
0
α
2
LD
0
vα
µ
2
=
µ
2
(
L
)
−
µ
2
(0)
=
=
.
V
0
Application of the method
Packed tube:
1 Measure
V
0
.
2 Perform pulse injection experiment.
3 Calculate two system parameters using moments calculated from experimental results:
V
0
L
µ
1
)
α
=
(
V
0
2
L
D
0
=
2
(
µ
2
)
.
α
Open tube
(
α
=
1):
L
µ
1
V
0
=
V
0
D
0
=
2
L
(
µ
2
)
.
µ
1
and
Numerical values of
µ
2
are obtained from integration of the experimental
measurements using the definition of the first and second moments.
[
Note
: all results to this point are valid
only
for
inert
packed beds.]
C.2.2 Example C.2
Consider a packed column where we need to account for:
1 pore diffusion;
2 mass transfer to particle surface;
3 adsorption at the pore surface.
There are spherical packing particles of uniform size, Figure C.3. We need to evaluate
the mass transfer rate both in the interstitial fluid (space between particles) and in the
intra-particle void space (pores).
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