Heat and Mass Transfer Properties of Sugar Maple Wood Treated by the Thermo-Hygro-Mechanical Densification Process

Qilan Fu,Aziz Laghdir,Alain Cloutier

doi:10.3390/fib6030051

Abstract

This study investigated the evolution of the density, gas permeability, and thermal conductivity of sugar maple wood during the thermo-hygro-mechanical densification process. The results suggested that the oven-dry average density of densified samples was significantly higher than that of the control samples. However, the oven-dry density did not show a linear increase with the decrease of wood samples thickness. The radial intrinsic gas permeability of the control samples was 5 to 40 times higher than that of densified samples, which indicated that the void volume of wood was reduced notably after the densification process. The thermal conductivity increased by 0.5–1.5 percent for an increase of one percent moisture content for densified samples. The thermal conductivity of densified wood was lower than that of the control samples. The densification time had significant effects on the oven-dry density and gas permeability. Both densification time and moisture content had significant effects on thermal conductivity but their interaction effect was not significant.

Highlights

The heat and mass transfer properties of wood or wood-based materials are essential characteristics required for a variety of purposes, including the heat and mass transfer modeling during the densification process and characterization of densified wood as a building material.Among others, typical properties required are density, permeability, and thermal conductivity.A proper characterization of these properties is crucial for increasing the accuracy of model predictions.during the thermo-hygro-mechanical (THM) densification process, density, permeability, and thermal conductivity of wood are all time-dependent, which makes the characterization of these parameters difficult.Bulk flow is the principal mechanism for the transport of fluids through wood, which occurs through the voids of the wood under a static or capillary pressure gradient [1]
40 min,profiles respectively, selected to investigate the density sample densified for min and min, respectively, were selected to investigate the density distribution through its thickness undergoing different densification time treatments
5, the density of the control sample was almost constant throughout the thickness, with the exception of the lower density values observed on both surfaces

Summary

Introduction

The heat and mass transfer properties of wood or wood-based materials are essential characteristics required for a variety of purposes, including the heat and mass transfer modeling during the densification process and characterization of densified wood as a building material.Among others, typical properties required are density, permeability, and thermal conductivity.A proper characterization of these properties is crucial for increasing the accuracy of model predictions.during the thermo-hygro-mechanical (THM) densification process, density, permeability, and thermal conductivity of wood are all time-dependent, which makes the characterization of these parameters difficult.Bulk flow is the principal mechanism for the transport of fluids through wood, which occurs through the voids of the wood under a static or capillary pressure gradient [1]. The heat and mass transfer properties of wood or wood-based materials are essential characteristics required for a variety of purposes, including the heat and mass transfer modeling during the densification process and characterization of densified wood as a building material. Typical properties required are density, permeability, and thermal conductivity. During the thermo-hygro-mechanical (THM) densification process, density, permeability, and thermal conductivity of wood are all time-dependent, which makes the characterization of these parameters difficult. Bulk flow is the principal mechanism for the transport of fluids through wood, which occurs through the voids of the wood under a static or capillary pressure gradient [1]. Comstock [3] reported that the arrangement of wood principal directions has more impact on its gas permeability than any other parameter.

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