Fibre level modelling of free water behaviour during wood drying and wetting

Most drying simulation models describe the moisture migration in wood as a diffusion process, including free water flow at contents greater than the fibre saturation point. This means that wood is seen as a homogeneous material lacking internal structure. However, especially in softwood narrow secti...

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Autor principal:	Salin,Jarl-Gunnar
Lenguaje:	English
Publicado:	Universidad del Bío-Bío 2011
Materias:	Capillarity free water modelling percolation wood drying wetting
Acceso en línea:	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2011000200003
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spelling	oai:scielo:S0718-221X20110002000032011-08-24Fibre level modelling of free water behaviour during wood drying and wettingSalin,Jarl-Gunnar Capillarity free water modelling percolation wood drying wetting Most drying simulation models describe the moisture migration in wood as a diffusion process, including free water flow at contents greater than the fibre saturation point. This means that wood is seen as a homogeneous material lacking internal structure. However, especially in softwood narrow sections, bordered pits, divide the free water phase into rather distinct units. It is thus quite clear that the flow of free water is governed by capillary forces and not by diffusion. A model has been developed that investigates how water filled units are emptied one by one in a drying process. Simulations with the model explain some experimentally seen features that cannot be obtained using solely diffusion type models. Water absorption by dried wood is generally assumed to be governed by capillary (surface tension) forces. An additional feature is that a considerable part of the bordered pits have been aspirated, i.e. closed, in the drying process and the number of possible flow paths is thus reduced. Thus the driving force for water flow is the capillary suction into the lumen. Modelling wood wetting by these principles also introduces some interesting specific features, such as a limit regarding the maximal achievable water saturation. In summary it is found that specific behaviour seen on a real macroscopic level originates from properties at the microscopic, fibre level. This clearly indicates that experience from fibre level models should be included in future drying and wetting simulation models. The work in this direction so far, has been promising.info:eu-repo/semantics/openAccessUniversidad del Bío-BíoMaderas. Ciencia y tecnología v.13 n.2 20112011-01-01text/htmlhttp://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2011000200003en10.4067/S0718-221X2011000200003
institution	Scielo Chile
collection	Scielo Chile
language	English
topic	Capillarity free water modelling percolation wood drying wetting
spellingShingle	Capillarity free water modelling percolation wood drying wetting Salin,Jarl-Gunnar Fibre level modelling of free water behaviour during wood drying and wetting
description	Most drying simulation models describe the moisture migration in wood as a diffusion process, including free water flow at contents greater than the fibre saturation point. This means that wood is seen as a homogeneous material lacking internal structure. However, especially in softwood narrow sections, bordered pits, divide the free water phase into rather distinct units. It is thus quite clear that the flow of free water is governed by capillary forces and not by diffusion. A model has been developed that investigates how water filled units are emptied one by one in a drying process. Simulations with the model explain some experimentally seen features that cannot be obtained using solely diffusion type models. Water absorption by dried wood is generally assumed to be governed by capillary (surface tension) forces. An additional feature is that a considerable part of the bordered pits have been aspirated, i.e. closed, in the drying process and the number of possible flow paths is thus reduced. Thus the driving force for water flow is the capillary suction into the lumen. Modelling wood wetting by these principles also introduces some interesting specific features, such as a limit regarding the maximal achievable water saturation. In summary it is found that specific behaviour seen on a real macroscopic level originates from properties at the microscopic, fibre level. This clearly indicates that experience from fibre level models should be included in future drying and wetting simulation models. The work in this direction so far, has been promising.
author	Salin,Jarl-Gunnar
author_facet	Salin,Jarl-Gunnar
author_sort	Salin,Jarl-Gunnar
title	Fibre level modelling of free water behaviour during wood drying and wetting
title_short	Fibre level modelling of free water behaviour during wood drying and wetting
title_full	Fibre level modelling of free water behaviour during wood drying and wetting
title_fullStr	Fibre level modelling of free water behaviour during wood drying and wetting
title_full_unstemmed	Fibre level modelling of free water behaviour during wood drying and wetting
title_sort	fibre level modelling of free water behaviour during wood drying and wetting
publisher	Universidad del Bío-Bío
publishDate	2011
url	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2011000200003
work_keys_str_mv	AT salinjarlgunnar fibrelevelmodellingoffreewaterbehaviourduringwooddryingandwetting
_version_	1714202552744017920

Fibre level modelling of free water behaviour during wood drying and wetting

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