Modelisation des transferts couples de chaleur et de masse avec changement de phase en milieux poreux
Application au sechage en vapeur d'eau surchauffee
Keywords:
heat transfer, fluid flow, porous mediaAbstract
The physical model is based on balance equations at the representative elementary volume. The considered medium has three phases (liquid, solid and gaseous phases). The gaseous phase includes two components (air and steam). We use the mass balance equations over air and water (liquid and steam) as well as heat equation in order to describe the phenomena. The system of equations is closed via classical relations in this media, which lead to a three equations system with coupled nonlinear partial derivatives. We have applied this model to the superheated steam drying. A solution model of the coupled nonlinear equations system based on the finite element method in a 2D configuration was developped and validated. This approach allows to determine the whole variables of the problem. It is a complementary tool of analysis which opens access to non mesurable variables, such as phases velocities. This computation model was applied to a configuration studied experimentally. The numerical and experimental results agree in non-dimensional time. This double approach has enabled us to point out and evaluate new mechanisms typical from this d!)'ing methods.
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