Measurement and Evaluation of Moisture Transport Coefficients During Drying of Wood

Abstract

Measurements of moisture content gradients were performed during drying of Scots pine (Pinus sylvestris). The measurements were done in heartwood and sapwood separately and in all three directions to grain separately. The aim of these measurements was to evaluate Kirchhoff flow potentials and diffusion coefficients in a moisture content range from about fibre saturation to end-use dried. A new method to evaluate flow coefficients from transient measurements is presented. This new method, called the Kirchhoffian moment method, gave good results in a moisture content range from about 30 % and down to 8 % moisture content.

Finite Changes of Bound Water Moisture Content in a Given Volume of Beech Wood

“…There are some methods for analyzing the constancy of diffusion coeffi cient -Egner's method (Skaar, 1954), Rosenkilde and Arfvidsson (1997), and methods based on the wood drying data (Dekrét and Trebula, 1999) if moisture fi eld is known, or numerical methods for evaluating the sorption measurements if the dependency of diffusion coeffi cient on moisture content is prescribed (Olek et al, 2005). Siau (1984) published the exponential function of the diffusion coeffi cient on moisture content and Stamm (1964) and Choong (1963) found out its increasing dependence on temperature according to Arhenius equation.…”

Parameter influence on moisture induced eigen-stresses in timber

“…The moisture transport is modelled as a diffusion process and the wood material is treated as isotropic in the transversal directions (experiments on Nordic softwood have shown that the diffusion coefficients are practically the same in the tangential and the radial direction, see, e.g., Rosenkilde and Arfvidsson 1997, Hedenblad 1996and Hukka 1999 …”

Reducing spatial dimensionality in a model of moisture diffusion in a solid material

“…Using Eqs. (11) and (12) the width as well as the degree of coating of the edges can be chosen to be sure that the error of calculations will not be greater than the required one in the case of use of the 1-D model. The kind of adjustment (width or coating of the edges) depends on possibilities.…”

“…Moisture movement models have been also successfully used to solve the inverse coefficient problem [9][10][11][12]. In those cases, it is assumed that the type of governing equations is known.…”