Thermodynamically coupled mass transport processes in a saturated clay
Gradients of temperature, pressure, and fluid composition in saturated clays give rise to coupled transport processes (thermal and chemical osmosis, thermal diffusion, ultrafiltration) in addition to the direct processes (advection and diffusion). One-dimensional transport of water and a solute in a saturated clay subjected to mild gradients of temperature and pressure was simulated numerically. When full coupling was accounted for, volume flux (specific discharge) was controlled by thermal osmosis and chemical osmosis. The two coupled fluxes were oppositely directed, producing a point of stagnation within the clay column. Solute flows were dominated by diffusion, chemical osmosis, and thermal osmosis. Chemical osmosis produced a significant flux of solute directed against the gradient of solute concentration; this effect reduced solute concentrations relative to the case without coupling. Predictions of mass transport in clays at nuclear waste repositories could be significantly in error if coupled transport processes are not accounted for. 14 references, 8 figures, 1 table.
- Research Organization:
- Lawrence Berkeley Lab., CA (USA)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 6195242
- Report Number(s):
- LBL-18715; CONF-841157-46; ON: DE85004594
- Resource Relation:
- Conference: Symposium on the scientific basis for nuclear waste management, Boston, MA, USA, 26 Nov 1984; Other Information: Portions are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
54 ENVIRONMENTAL SCIENCES
CLAYS
MASS TRANSFER
ADVECTION
EXPERIMENTAL DATA
OSMOSIS
PRESSURE GRADIENTS
TEMPERATURE GRADIENTS
THERMAL DIFFUSION
ULTRAFILTRATION
DATA
DIFFUSION
FILTRATION
INFORMATION
NUMERICAL DATA
SEPARATION PROCESSES
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