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Mass diffusity of wood determined by inverse method from electrical resistance measurement in unsteady state.

Abstract : Mass diffusivity is one of the physical properties that characterizes the migration of bound moisture in porous media in general and in wood in particular. Its control is essential to understand and to simulate the drying process as well as impregnation phenomena or moisture transfers through building walls. In this study, a fast and reliable method for the determination of mass diffusivity by electrical measurements in transient state has been developed. This method consists in three complementary steps: experimentation, analysis of experimental data thanks to a coupled heat and mass transfer numerical code (TransPore) and minimization of the difference between the experimental data and the simulated ones. The experimentation is based on measurements of the electrical resistance of wood sample in transient state. A megohmmeter associated to a multiplexer allows measurements on several samples at the same time. The code TransPore computes the electrical resistance of each sample thanks to the moisture content field. That has been simulated from the real experimental conditions. The Simplex algorithm minimizes the gap between experimental and theoretical results by fitting the significant parameters such as mass diffusivity. The method ability was established by comparison with the very widely used weighting technique for mass diffusivity determination. The efficiency of this new method allows us to characterize the wood diffusivity of six tropical species and six temperate ones. However, the weighting technique has been preferred to characterize the mass diffusivity of heat treated wood and shows that the mass diffusion coefficient of natural wood was reduced by at least 60% after heat treatment.
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Contributor : Ecole Agroparistech <>
Submitted on : Thursday, November 4, 2004 - 8:00:00 AM
Last modification on : Thursday, November 4, 2004 - 8:00:00 AM
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Adéyèmi Clément Kouchade. Mass diffusity of wood determined by inverse method from electrical resistance measurement in unsteady state.. Life Sciences [q-bio]. ENGREF (AgroParisTech), 2004. English. ⟨pastel-00000888⟩

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