Lors de la fusion du verre, de nombreuses petites bulles de gaz sont produites. L’affinage du verre a pour objectif de faire disparaitre ces bulles par l’ajout d’espèces réactives contribuant à la résorption des bulles ou à une augmentation de leur taille. La modélisation de l’hydrodynamique et des transferts nécessite l’étude des couplages entre convection, diffusion et réaction. Une approche locale à l’échelle de la bulle (simulation directe du transfert réactif et de l’écoulement) est utilisée pour déterminer le transfert interfacial. Des mesures de la propagation de fronts d’oxydation dans la fonte ont permis de préciser certaines propriétés physiques des espèces réactives. L’ensemble de cette analyse multi-échelles a contribué à l’élaboration d’un modèle de simulation d’un nuage de bulles / Many bubbles are generated during glass production. Due to the high viscosity of molten glass, their rising velocity is extremely low. The refining step consists in adding reactive agents to improve the glass quality. Bubble release is enhanced by chemical reaction (iron and sulfate oxidation-reduction) which will favor shrinkage or growth of bubbles through interfacial mass transfer. Better understanding of bubble cloud behavior in molten glass requires studying the interplay between convection, diffusion and chemical reactions. The direct numerical simulation of the flow and reactive mass transfer provided new insights on modeling interfacial bubble gas fluxes. The acceleration factor has been determined for simple reversible reactions in order to validate the simulation tool. Different Péclet and Damkhöler numbers have been tested to map all the different regimes (diffusion, convection and reaction). Together with those simulations, we have carried out series of experiments in molten glass : propagation of oxidation fronts. At different temperatures and for various glass compositions, we have determined physical properties of reactive species. A theoretical model of reactive transport for instantaneous reactions has been proposed to interpret experimental data. The core of this multi-scale analysis contributed to elaborating an Euler- Lagrange model to simulate bubble clouds in reactive media. This model has been applied to specific processes related to glass industry and can easily be extended to any reactive bubbly flows
| Identifer | oai:union.ndltd.org:theses.fr/2011INPT0108 |
| Date | 15 November 2011 |
| Creators | Perrodin, Marion |
| Contributors | Toulouse, INPT, Climent, Éric |
| Source Sets | Dépôt national des thèses électroniques françaises |
| Language | French |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation, Text |
Page generated in 0.002 seconds