Comparison of moisture diffusion coefficients for pine, oak and linden wood

作者：Perkowski Zbigniew^*; Swirska Perkowska Jadwiga; Gajda Marek

来源：Journal of Building Physics, 2017, 41(2): 135-161.

DOI：10.1177/1744259116673967

• Bound water diffusion
• water vapour diffusion
• effective diffusion coefficient
• wood
• sorption experiment
• minimization of objective function

This article presents experimental research on the moisture diffusivity in wood within the range of hygroscopic moisture. This research was carried out on samples of three types of trees: Scots pine, small-leaved linden and pedunculate oak. It included measurements of kinetics of moisture adsorption within the range of air relative humidity from 25% to 85%. For each type of wood, the experiment was carried out with unidirectional flow of moisture, in each of the material principal orthotropic directions, by examining the diffusion coefficient along the fibres, in the tangential direction and in the radial direction. Values of moisture diffusion coefficients and mass surface emission coefficient were found with the use of method of minimizing the objective function, that is, by fitting the computational adsorption kinetics curves to the experimental ones. At the same time, three cases of variations of the moisture diffusion coefficient together with moisture content of the material have been analysed each time: in the form of a constant, linear function and a quadratic function, assuming a constant value of mass surface emission coefficient on the absorbing surface of samples. The performed calculations allowed determining whether the moisture diffusion coefficients have extreme values within the analysed range of moisture content and what is the impact of various diffusion mechanisms on the whole process of transferring moisture in the considered cases.

• 出版日期2017-9