A model of moisture movement in wood based on water potential and the determination of the effective water conductivity
1993
Cloutier, A. | Fortin, Y.
A model of isothermal moisture movement in wood during drying using the gradient in water potential as the driving force is proposed. The moisture transport coefficient used in this model is the effective water conductivity. It is a function of moisture content, temperature, and direction of flow. The boundary desorption curve of the effective water conductivity function is established in the radial and tangential directions of aspen sapwood from nearly saturated to dry conditions at 20, 35, and 50 degrees C using the instantaneous profile method. The results show that the effective water conductivity increases exponentially with moisture content and temperature. The effect of temperature cannot be solely explained by the variation of the viscosity of water. The variation of the moisture content-water potential relationship with temperature would explain a large part of this effect. The effective water conductivity was generally higher in the radial direction than in the tangential direction in a ratio varying from 1/1 to 25/1 depending on moisture content and temperature. The flux-gradient relationship obtained at given moisture contents were found to be linear, confirming the validity of the model for the experimental conditions considered in the present work.
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