Diffusive Reactive Transport of Multicomponent Chemicals Under Coupled Thermal, Hydraulic, Chemical and Mechanical Conditions
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This paper presents an investigation of the reactive transport of multicomponent chemicals in clays under coupled thermal, hydraulic, chemical and mechanical framework, considering the diffusion processes in detail. More specifically, combined effects due to the electrochemical and the thermal diffusion potentials are investigated. A theoretical framework for coupling thermal diffusion, i.e. the Soret effect, with electrochemical diffusion in a multi-ionic system is provided. An explicit form of a definition for the thermal diffusion coefficient in a multicomponent chemical transport model is developed. Chemical transport is linked to an advanced geochemical model, PHREEQC (version 2), in order to include chemical reactions. The effects of the combined diffusion potentials on the reactive transport of multicomponent chemicals are investigated by a series of numerical simulations of coupled thermal, hydraulic and chemical behaviour.
KeywordsCoupled model THCM Clay Reactive transport Chemical diffusion Thermal diffusion
This work has been performed as part of the doctoral programme of the second author. The authors wish to thank the financial support of a PhD fellowship, from the Overseas Research Students Award Scheme (ORSAS), and the School of Engineering, Cardiff University. The authors also wish to acknowledge Dr. S.C. Seetharam, former Research Fellow at Geoenvironmental Research Centre, Cardifff University, UK; for his contribution and comments in the early stages of this work.
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