Effects of the method of identification of the diffusion coefficient on accuracy of modeling bound water transfer in wood

2007 ◽  
pp. 135-144
Author(s):  
Wieslaw Olek ◽  
Jerzy Weres
Keyword(s):  
Diffusion Coefficient ◽  
Bound Water ◽  
Water Transfer

scholarly journals Combined bound water and water vapour diffusion of Norway spruce and European beech in and between the principal anatomical directions

Holzforschung ◽  
2011 ◽  
Vol 65 (6) ◽  
pp. 819-828 ◽  
Author(s):  
Walter Sonderegger ◽  
Manuele Vecellio ◽  
Pascal Zwicker ◽  
Peter Niemz
Keyword(s):  
Diffusion Coefficient ◽  
Steady State ◽  
Water Vapour ◽  
Diffusion Coefficients ◽  
Bound Water ◽  
European Beech ◽  
Unsteady State ◽  
Water Vapour Diffusion ◽  
Vapour Diffusion ◽  
Water Vapour Resistance

Abstract The combined bound water and water vapour diffusion of wood is of great interest in the field of building physics. Due to swelling stresses, the steady-state-determined diffusion coefficient clearly differs from the unsteady-state-determined diffusion coefficient. In this study, both diffusion coefficients and the water vapour resistance factor of Norway spruce (Picea abies [L.] Karst.) and European beech (Fagus sylvatica L.) were investigated for the principal anatomical directions (radial, tangential and longitudinal) and in 15° steps between these directions. The values were determined with the cup method as the basic principle. The unsteady-state-determined diffusion coefficient is, independent of the direction, about half that of the steady-state-determined diffusion coefficient. Both diffusion coefficients are about two to three times higher for spruce than for beech. They are up to 12 times higher in the longitudinal direction than perpendicular to the grain for spruce, and up to 15 times higher for beech. With increasing moisture content, the diffusion coefficients exponentially increase. The water vapour resistance factor shows converse values to the diffusion coefficients.

The Volume Available to Diffusion in the Muscle Fiber

1974 ◽  
Vol 52 (4) ◽  
pp. 814-828 ◽  
Author(s):  
J. P. Caillé ◽  
J. A. M. Hinke
Keyword(s):  
Diffusion Coefficient ◽  
Muscle Fiber ◽  
Diffusion Coefficients ◽  
Pure Water ◽  
Bound Water ◽  
Water Volume ◽  
Glass Capillary ◽  
Fiber Volume ◽  
Binding Effect ◽  
Polyelectrolyte Solutions

Intrafiber diffusion of 3HOH, dimethyl-3H-sulfoxide (DMSO), D-14C-sorbitol, and 36Cl was measured along the longitudinal axis of the single muscle fiber (Balanus nubilus) that had been placed inside the lumen of a glass capillary at least 24 h beforehand. When the fiber contained 75% water, the mean self-diffusion coefficients (× 10−5 cm2/s) at 10 °C and at pH 7.5 were 0.908 ± 0.008 for water, 0.418 ± 0.008 for DMSO, 0.216 ± 0.005 for sorbitol, and 0.683 ± 0.006 for chloride. These diffusion coefficients in myoplasm were 0.53–0.58 times the values in pure water. Diffusions of the above were also measured in fibers with reduced water content, as low as 45% by weight. In all cases, the diffusion coefficient decreased in proportion to the reduction in the fiber water. With the aid of Wang's theory for diffusion in polyelectrolyte solutions, we have attempted to separate the "obstruction effect" from the "binding effect", both of which operate to reduce the diffusion coefficient of substances in the myoplasm. Our analysis indicates that the diffusible volume in myoplasm (75% water) for all substances is about 80% of the water volume or 65% of the fiber volume. So-called "bound" water in myoplasm is estimated to be 0.57 g water per gram dry weight.

Brief-Measurements of Vapor Diffusion Coefficient

1954 ◽  
Vol 46 (11) ◽  
pp. 47-49 ◽  
Author(s):  
C.Y. Lee ◽  
C.R. Wilke
Keyword(s):  
Diffusion Coefficient ◽  
Vapor Diffusion

Velocity and diffusion coefficient of a random asymmetric one-dimensional hopping model

1989 ◽  
Vol 50 (8) ◽  
pp. 899-921 ◽  
Author(s):  
C. Aslangul ◽  
N. Pottier ◽  
D. Saint-James
Keyword(s):  
Diffusion Coefficient ◽  
One Dimensional ◽  
And Diffusion ◽  
Hopping Model
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