Experimental determination of hydraulic conductivity of pine samples in the longitudinal direction during convective drying

In studying the process of drying wood samples, the hydraulic conductivity of pine samples exposed to a convective air flow was measured in the direction perpendicular to the cross-sectional plane of the tree (along the wood grain). The kinetic curves of the drying process were treated with a technique based on the approximate solution of the one-dimensional diffusion equation for hydraulic conductivity of wood with a boundary condition of the third kind. The technique was tested on the basis of the known value of hydraulic conductivity in the direction tangential to annual rings of the tree. It is shown that the hydraulic conductivity in the longitudinal direction is 17 times the hydraulic conductivity in the direction tangential to the annual rings in the cross-sectional plane of the tree. By means of numerical simulation of the process, based on solving the initial-boundary problem for the two-dimensional linear equation of hydraulic conductivity, the effect of anisotropy of hydraulic conductivity coefficients on the dependence of the mean humidity on time and on the local humidity distribution is studied.