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Materials and Structures

, Volume 37, Issue 9, pp 615–622 | Cite as

A model for non-fickian moisture transfer in wood

  • K. Krabbenhoft
  • L. Damkilde
Scientific Report

Abstract

A model for non-Fickian moisture transfer in wood is presented. The model considers the transfer of water vapour separate from the transfer of bound water. These two components are linked by an equation describing the sorption on the cell wall level. Hereby, a formulation capable of describing known non-Fickian effects, including the effects of step size, absolute moisture content, and sample length, is achieved. The sorption curves predicted by the model are compared with experimental results and good agreement is found.

Keywords

Sorption Isotherm Sorption Rate Sorption Curve Vapour Transfer Target Moisture Content 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Nomenclature

Roman letters

D

Diffusion coefficient

E

Fractional weight increase

h

Sorption constant (kgm−3s−1Pa−1)

j

Flux (kgm−2s−1)

m

Moisture content (kg/kg)

\(\dot m\)

Sorption term (kgm−3s−1)

p

Pressure (Pa)

r

Relative humidity (RH)

R

Gas constant (8.31 Jmol−1K−1)

T

Temperature (K)

w

Moisure content (kgm−3)

Greek letters

Φ

Porosity

σ

Density (kgm−3)

ξ

Internal area/volume ration (m−1)

τ

Vapour diffusivity reduction factor

Sub-and superscripts

a

air

eff

effective

g

gas—vapour+air

L

longitudinal

T

tangential

v

vapour

Réssumé

Un modèle pour le transfert non-Fickien d'humidité dans le bois est présenté. Le modèle considère le transfert de la vapeur d'au séparé pour le transfert de l'eau liée. Ces deux composants sont liés par une équation décrivant la sorption au niveau de mur de cellules. Par ceci, une formulation capable de décrire des effets non-Fickian connus, comprenant les effets de la taille d'étape, le contenu d'humidité absolu, et la longueur d'échantillon, est réalisée. Les courbes de sorption prévues par le modèle sont comparées aux résultats expérimentaux et une bonne concordance est trouvée.

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Copyright information

© RILEM 2004

Authors and Affiliations

  • K. Krabbenhoft
    • 1
  • L. Damkilde
    • 2
  1. 1.Department of Civil EngineeringTechnical University of DenmarkLyngbyDenmak
  2. 2.Institute of Chemistry and Applied Engineering ScienceAalborg University EsbjergEsbjergDenmark

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