Journal of Wood Science

, Volume 52, Issue 3, pp 195–201 | Cite as

Local water vapor diffusion coefficient when drying Norway spruce sapwood

  • Jonas Danvind
  • Mats EkevadEmail author
Original Article


In this article, a one-dimensional and a two-dimensional approach to the evaluation of local diffusion coefficients for Norway spruce sapwood from measured moisture content (MC) values are presented. A studied wood sample was dried from the initial green condition to about 15% mean MC, but here only the diffusive part of the drying process between approximately 25% and 15% mean MC was treated. Measured local MC values were based on nondestructive X-ray computed tomography data. Finite element calculations were performed with two alternative diffusion coefficients to test the appropriateness of the diffusion coefficients that were evaluated from the measured MC values. The evaluated diffusion coefficients show interesting dependence on MC and distance from the evaporation surface. The advantage of using the methods presented is that the diffusion coefficient is calculated on a local level without having to define a function for the diffusion coefficient’s dependency on other parameters.

Key words

Wood FEM Drying Diffusion coefficient Computed tomography 


  1. 1.
    Hukka A (1999) The effective diffusion coefficient and mass transfer coefficient of Nordic softwoods as calculated from direct drying experiments. Holzforschung 53:534–540Google Scholar
  2. 2.
    Hukka A, Oksanen O (1999) Convective mass transfer coefficient at wooden surface in jet drying of Veener. Holzforschung 53:204–208Google Scholar
  3. 3.
    Liu JY, Simpson WT, Verrill SP (2001) An inverse moisture diffusion algorithm for the determination of diffusion coefficient. Dry Technol 19:1555–1568CrossRefGoogle Scholar
  4. 4.
    Rosenkilde A, Arfvidsson J (1997) Measurement and evaluation of moisture transport coefficients during drying of wood. Holzforschung 51:372–380CrossRefGoogle Scholar
  5. 5.
    Lindgren O (1992) Medical CT-scanners for non-destructive wood density and MC measurements. Doctoral Thesis, Luleå University of Technology, Thesis No. 1992:111DGoogle Scholar
  6. 6.
    Danvind J, Morén T (2004) Using X-ray CT-scanning for moisture and displacement measurements in knots and their surroundings. EU COST 15 Wood Drying Conference Proceedings, April 22–23, Athens, GreeceGoogle Scholar
  7. 7.
    Wiberg P (2001) X-ray CT-scanning of wood during drying. Doctoral Thesis, Luleå University of Technology, Thesis No. 2001:10Google Scholar
  8. 8.
    Ekevad M (2004) Method to compute fiber directions in wood from computed tomography images. J Wood Sci 50:41–46CrossRefGoogle Scholar
  9. 9.
    Sepulveda P, Oja J, Grönlund A (2002) Predicting spiral grain by computed tomography of Norway spruce. J Wood Sci 48:479–483CrossRefGoogle Scholar
  10. 10.
    Anon (2001) Matlab version release 12.1. The MathWorks, Natick, MAGoogle Scholar
  11. 11.
    Anon (2003) ABAQUS users manual version 6.4. ABAQUS, Pawtucket, RIGoogle Scholar
  12. 12.
    Salin JG (2002) Theoretical analysis of mass transfer from wooden surfaces. Proceedings of 13th International Drying Symposium, 27–30 August, Beijing, ChinaGoogle Scholar
  13. 13.
    Danvind J (2002) Measuring strain and moisture content in a crosssection of drying wood using digital speckle photography and computerized X-ray tomography. Proceedings of 13th International Symposium on Nondestructive Testing of Wood. 19–21 August, Berkley, CA, USAGoogle Scholar

Copyright information

© The Japan Wood Research Society 2006

Authors and Affiliations

  1. 1.Division of Wood Technology, Skellefteå CampusLuleå University of TechnologySkellefteåSweden
  2. 2.SkellefteåSweden

Personalised recommendations