Determination of the Material Property Variations Across the Growth Ring of Softwood for Use in a Heterogeneous Drying Model. Part 2. Use of Homogenisation to Predict Bound Liquid Diffusivity and Thermal Conductivity

Abstract

Summary In this work, the extensive knowledge of wood gained at the Ecole Nationale du Génie Rural des Eaux et Forêts by using a combination of microscopic observation and experimental work is being used to postulate material property correlations for a macroscopic heterogeneous “Cerne” growth ring model of softwood. In this second part, the method of homogenisation is used to capture the contrast of property between the gaseous phase and the solid phase. Homogenisation problems are computed using a Control Volume formulation. The tracheid model developed in Part 1 has been used to define several elementary representative volumes. Consequently, bound water diffusivity and thermal conductivity can be predicted for each material direction as a function of local wood density. For practical applications, analytical models fitted from the computed values allow these property variations to be easily and accurately determined.