A new two-scale model describing drying dynamics and coupled heat and mass transfer in a porous  medium: application to the combined vacuum drying and radiative heating of wood

Turner, Ian; Perré, Patrick

A new two-scale model describing drying dynamics and coupled heat and mass transfer in a porous medium: application to the combined vacuum drying and radiative heating of wood

2007

Turner, Ian | Perré, Patrick

In this work a two-scale modelling approach is used to investigate the vacuum drying of a board placed in an experimental vacuum chamber, whereby two infrared emitters with reflectors are used to supply heat to the product. The kiln (large) scale model allows the evolution of the masses of vapour, air and water in the chamber, together with the temperatures of the vacuum chamber and the IR emitters to be monitored throughout the drying process. Such a model enables condensation on the kiln walls to be accounted for in the evolution of the relative humidity within the chamber. The comprehensive two-dimensional drying model, known as Transpore, is used to determine the heat and mass transfer at the (macro) scale of the board. The knowledge of the vacuum chamber vapour pressure at any given instant using the large-scale model enables the intricate coupling that exists between the wood and the chamber to be realised throughout the simulation. This innovative modelling approach provides a precise description of the experimental configuration for which the model can be verified. Finally, two case studies are presented to elucidate the coupling that exists between the technical specifications of the chamber and the drying mechanisms in the porous medium.

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