Environmental Engineering Reference
In-Depth Information
Ta b l e 4 . 16
The diffusion coefficient of metal
clusters in a gas
mal density of atoms, are expressed in square
centimeters per second, and correspond to
gas temperature
D
0
in the kinetic regime of
cluster drift in accordance with (4.114). The
diffusion coefficients are reduced to the nor-
T
D
600 K.
Cluster, gas
He
Ne
Ar
Kr
Xe
H
2
N
2
Ti
2.2
1.0
0.71
0.49
0.39
3.2
0.85
Fe
2.9
1.3
0.91
0.63
0.50
4.2
1.1
Co
3.0
1.3
0.95
0.65
0.52
4.0
1.1
Ni
3.0
1.3
0.95
0.65
0.52
4.0
1.1
Cu
2.9
1.3
0.91
0.63
0.50
4.2
1.1
Zn
2.5
1.1
0.79
0.54
0.43
3.5
0.94
Sr
2.1
0.94
0.66
0.46
0.37
3.0
0.80
Mo
2.4
1.1
0.77
0.53
0.42
3.4
0.92
Pd
2.4
1.1
0.77
0.53
0.42
3.4
0.92
Ag
2.2
1.0
0.71
0.49
0.39
3.2
0.85
Ba
0.96
0.43
0.30
0.21
0.17
1.4
0.36
Ta
2.2
0.98
0.70
0.48
0.38
3.1
0.83
W
2.4
1.1
0.76
0.52
0.42
3.4
0.90
Re
2.5
1.1
0.79
0.54
0.43
3.5
0.94
Ir
2.4
1.1
0.78
0.54
0.43
3.4
0.93
Pt
2.5
1.1
0.80
0.55
0.44
3.5
0.95
Au
2.3
1.0
0.72
0.50
0.40
3.2
0.86
Tl
1.7
0.74
0.53
0.36
0.29
2.3
0.63
Pb
1.6
0.71
0.51
0.35
0.28
2.2
0.60
U
2.0
0.88
0.63
0.43
0.34
2.8
0.75
Pu
2.1
0.96
0.68
0.47
0.37
3.0
0.81
In the limit of small Knudsen numbers (Kn
1) this formula is converted in-
to (4.114), and in the limit of large Knudsen numbers (Kn
1) it is transformed
into (4.110). In particular, if water clusters (drops) of radius
r
0
move in air with
temperature
T
D
300 K, (4.116) takes the form
1
,
k
r
0
1
Nr
0
s
0
D
D
C
where
N
is the number density of air molecules, and the other parameters in this
formula are
k
D
10
19
cm
2
.
Let us determine the boundary number density of atoms or molecules
N
when
the contributions to the cluster diffusion coefficient due to the kinetic and diffusion
regimes are identical. Then we have from (4.116)
1.2
10
11
cm
3
/s and
s
0
D
4.3
1.56
σ
N
r
0
D
.
g
