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Genre/Form: | Thèses et écrits académiques |
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Material Type: | Document, Thesis/dissertation, Internet resource |
Document Type: | Internet Resource, Computer File |
All Authors / Contributors: |
Florian Cazenave; Philippe Bernada; Jean-Paul Serin; Université de Pau et des Pays de l'Adour.; École doctorale sciences exactes et leurs applications (Pau, Pyrénées Atlantiques).; Laboratoire de thermique, énergétique et procédés (Pau). |
OCLC Number: | 1128269508 |
Notes: | Titre provenant de l'écran-titre. |
Description: | 1 online resource |
Responsibility: | Florian Cazenave ; sous la direction de Philippe Bernada et de Jean-Paul Serin. |
Abstract:
In the framework of the theme devoted to the energy transition, the “Laboratoire de Thermique Energétique et Procédés” (LaTEP) is working on deep geothermal energy. This thesis focuses on the study of the fouling phenomenon of surface heat exchangers and more specifically on the modelling and the simulation of the evolution of a deposit. Fouling leads to loss of efficiency and requires means of prevention and cleaning, leading to huge over-costs. The proposed general model describes heterogeneous reactions between two multi-component phases, one liquid and the other solid. The liquid phase is a solution containing ions diluted in a solvent, while the solid is composed of immobile constituents. Transport by electro-migration is taken into account in the description. At the interface between the two phases, multiple heterogeneous reactions occur. The boundary conditions involves the interface's velocity and allow a complete coupling between the two domains. This general model is then applied to the particular case of fouling of a pipe by salt formation and is solved using Comsol Multiphysics. Simulation of a simplified case of fouling from barium sulfate allowed an analysis of the phenomenology of the deposit growth. It highlights the effects of changes in solubility and kinetics caused by the temperature drop in the tube, as well as the effect of radial mobility of the species by diffusion, limiting the growth. Electro-migration contributes significantly to transport but does not influence the thickness of the deposit. The hypothesis of an instantly balanced barite crystallization reaction leads to an overestimation of the fouling. In a second time, more species are added to the water's composition in order to study the influence of the presence of sodium chloride at 1 mol.L-1. Finally, the addition of strontium ions leads to co-precipitation of barite and celestine.
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