ED Sciences Physiques et de l'Ingénieur
Design and development of a reduced model for simulating the dielectric drying of wood
by Henri LACCASSAGNE (I2M - Institut de Mécanique et d'Ingénierie de Bordeaux)
The defense will take place at 14h00 - Amphi 3 - Bâtiment A9 Université de Bordeaux - Campus Peixotto, Batiment A9, 33400 Talence
in front of the jury composed of
- Régis POMMIER - Chargé de recherche - Université de Bordeaux - Directeur de these
- Patrick SALAGNAC - Professeur des universités - Université de la Rochelle - Rapporteur
- Hedi ROMDHANA - Maître de conférences - AgroParisTech - Rapporteur
- Wahbi JOMAA - Professeur des universités - Université de Bordeaux - CoDirecteur de these
- François DEMONTOUX - Professeur des universités - Université de Bordeaux - Examinateur
- Romain RéMOND - Maître de conférences - Université de Lorraine - Examinateur
Modelling the dielectric drying of wood, in order to satisfy both energy-controlled moisture transfer and sanitary treatments for fungi and pesticides, requires several coupled approaches to physics: multi-scale and multi-phase. The aims of the thesis are to design a tool for optimising the process as a whole. Applied to a multimode cavity, a new type of coupling is proposed, combining the development of a drying model based on Whitaker's volume averaging method with an electromagnetic model based on Maxwell's equations. Using a parametric frequency study, the coupling is used to calculate the microwave power dissipated in the wood as a function of its water content and temperature. These data are then interpolated to establish a function relating the power absorbed to the internal conditions of the wood, which is then incorporated into the drying model. Experimental tests have shown that the flow of water is clearly due to the release of pressure and heat at the heart of the wood. This mechanism is added to our modelling to assess its impact on the process as a function of the most influential input parameters. A metamodel is designed based on all these determining parameters. Finally, it was successfully used on a demonstrator to regulate temperature during drying.