Page 28 - gas transport in porous media

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Chapter 2: Gas Transport Mechanisms
The above expressions for b DGM and τ DGM have been evaluated by Webb and
◦
Pruess (2003) for a bulk species of air at 25 C and a porous media with a porosity of
0.4 and a tortuosity of 0.74. The permeability was varied over a wide range, and the
trace gas species include He, water vapor, and TCE.
Figure 2.4 shows the variation in the correction factors as a function of permeability
for three different trace gases (He, H 2 O, and TCE) at three different gas pressures
P= 1 atmosphere
1 3.00
2.50
He
2.00
TCE
τ DGM 0.1 H 2 O b DGM 1.50 H 2 O
He
1.00
0.50 TCE
0.01 0.00
–18 –17 –16 –15 –14 –13 –12 –11 –10 –18 –17 –16 –15 –14 –13 –12 –11 –10
10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10
2
2
Permeability (m ) Permeability (m )
P=10 atmospheres
1 3.00
2.50
He
TCE 2.00
τ DGM 0.1 H 2 O b DGM 1.50 H 2 O
He
1.00
0.50 TCE
0.01 0.00
10 –18 10 –17 10 –16 10 –15 10 –14 10 –13 10 –12 10 –11 10 –10 10 –18 10 –17 10 –16 10 –15 10 –14 10 –13 10 –12 10 –11 10 –10
2
2
Permeability (m ) Permeability (m )
P=100 atmospheres
1 3.00
2.50
TCE 2.00
H 2 O
τ DGM 0.1 He b DGM 1.50 H 2 O He
1.00
TCE
0.50
0.01 0.00
10 –18 10 –17 10 –16 10 –15 10 –14 10 –13 10 –12 10 –11 10 –10 10 –18 10 –17 10 –16 10 –15 10 –14 10 –13 10 –12 10 –11 10 –10
2
2
Permeability (m ) Permeability (m )
Figure 2.4. Trace gas correction factors as a function of pressure, permeability, and trace gas (reprinted
from Webb and Pruess, 2003 with permission)