Moisture distribution changes during drying

Wiberg, Pär

doi:10.1007/s001070050118

Cited by 10 publications

(5 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Figure 14 shows a dramatic change in the moisture content gradient between 9.2 and 10 hours. A similar observation to this has also been made by Cloutier et al (1992) and Wiberg (1995). This is partly explained by Spolek and Plumb (1981 pressure is no longer possible as a moisture transport process.…”

Section: Measurementssupporting

confidence: 78%

See 1 more Smart Citation

Measurement and Evaluation of Moisture Transport Coefficients During Drying of Wood

Rosenkilde¹,

Arfvidsson²

1997

Holzforschung

View full text Add to dashboard Cite

Measurements of moisture content gradients were performed during drying of Scots pine (Pinus sylvestris). The measurements were done in heartwood and sapwood separately and in all three directions to grain separately. The aim of these measurements was to evaluate Kirchhoff flow potentials and diffusion coefficients in a moisture content range from about fibre saturation to end-use dried. A new method to evaluate flow coefficients from transient measurements is presented. This new method, called the Kirchhoffian moment method, gave good results in a moisture content range from about 30 % and down to 8 % moisture content.

show abstract

Section: Measurementssupporting

confidence: 78%

“…This provides a suddenly increased resistance to moisture transport within the specimen that develops the steep moisture content gradient in Figure 14 between 9.2 and 10 hours. Wiberg (1995) concludes that the free water in sapwood migrate due to capillary forces towards the surface where bound water diffusion controls the drying rate.…”

Section: Measurementsmentioning

confidence: 97%

Measurement and Evaluation of Moisture Transport Coefficients During Drying of Wood

Rosenkilde¹,

Arfvidsson²

1997

Holzforschung

View full text Add to dashboard Cite

show abstract

“…The length of this part did not change at various sample lengths: approximately 2-3 mm from each sample surface, which is close to the length of the sample tracheid cell, approximately 3.5 mm (Yokoyama et al 2011). It suggests that the tracheid cells near the surface were firstly dried; such a phenomenon was also found in previous works (Wiberg 1995;Wiberg and More ´n 1999;Xu et al 2017) for the samples still with a high averaged MC. One of the most intriguing findings is that the subsurface areas tended to have higher MC than inside areas after drying for several hours (i.e., at 100 % and 60 % reference MC), especially inside longer wood samples.…”

Section: Visualizing the MC Changes In The Wood Samplessupporting

confidence: 82%

Moisture transport dynamics in wood during drying studied by long-wave near-infrared hyperspectral imaging

Morita

Inagaki

et al. 2021

Cellulose

View full text Add to dashboard Cite

The complexities of wood microstructure cause difficulties in understanding water movement characteristics during drying. Here, the water transport dynamics in softwood (Japanese cypress) with different sample lengths (30 mm, 60 mm, and 90 mm) and various drying temperatures (30 °C, 60 °C, and 90 °C) were studied using a rapid and high-resolution moisture content (MC) mapping method based on long-wave near-infrared hyperspectral imaging (NIR-HSI). The observations of this study are as follows: slow drying at approximately 30 °C, the area near the subsurface of the wood samples tends to have higher MC than the central parts during drying, especially in the case of longer wood samples. For drying at higher temperatures, strongly bonded water appeared at the surface areas much earlier, which could easily cause sample deformation and cracking. Overall, the experimental results suggest the capillary effects could play a major role at the first stage of slow drying at fiber level; then, the transfers between bound and free water could play a significant power source in the second drying stage. It is expected that this study will be of help in providing a basis to study and simulate the drying characteristics of cellular and hydrophilic materials.

show abstract

“…If this is done, the transport at the surface controls the internal moisture state of the plank. This phenomenon of drying without internal moisture gradients is especially noticed when drying sapwood of Scandinavian softwoods at high moisture levels (Wiberg 1995, 1997and Rosenkilde 1996. When modelling water in vapour phase, the diffusion coef®cient, D, is assumed to be a function of moisture content and temperature according to Fig.…”

Section: Moisture Transportmentioning

confidence: 99%

Simulation of drying stresses in wood

Svensson

Mårtensson

2002

Holz als Roh- und Werkstoff

View full text Add to dashboard Cite

This article describes a study where laboratory and theoretical work on the fundamental hygro-mechanical behaviour of wood is applied on convective drying of sawn timber. A material model describing the behaviour of wood during drying is used to simulate drying stresses in timber. Cross-sections containing heartwood, sapwood and a combination of both are studied. Simulations are compared with measurements from whole batches of sawn timber subjected to drying. The stress simulations show good agreement with the measurements. It is further shown how an alteration of a drying schedule changes the results in terms of internal stresses. Simulations of drying may be used to improve the quality of sawn timber and/or for optimising drying schedules. It is believed that simulations of drying instead of using trial and error tests on batches of sawn timber will prove to give economical and environmental bene®ts. Simulation von Trocknungsspannungen in Holz. Teil II: Konvektive Lufttrocknung von Schnittholz Experimentelle und theoretische Untersuchungen des hygro-mechanischen Verhaltens von Holz werden auf die konvektive Trocknung von Schnittholz angewendet. Ein Modell, das die Materialeigenschaften von Holz wa Èhrend der Trocknung beschreibt, wird benutzt, um die Trocknungsspannungen im Schnittholz zu simulieren. Dabei werden Querschnitte untersucht, die Kernholz, Splintholz und Kombinationen der beiden enthalten. Die Simulationen werden mit Messungen beim Trocknen von Schnittholzstapeln verglichen. Die Simulationen zeigen eine gute U È bereinstimmung mit den Meûergebnissen. Ferner wird gezeigt, wie eine A È nderung des Trocknungsfahrplans die inneren Spannungen vera Èndert. Die Simulationen ko Ènnen verwendet werden, um die Qualita Èt des getrockneten Schnittholzes zu verbessern oder um die Trocknungsfahrpla Ène zu optimieren. Es ist anzunehmen, daû die Verwendung von Simulationen anstelle von experimentellen Versuchen o Èkonomische und o Èkologische Vorteile erwarten la Èût.

show abstract

Moisture distribution changes during drying

Cited by 10 publications

References 0 publications

Measurement and Evaluation of Moisture Transport Coefficients During Drying of Wood

Measurement and Evaluation of Moisture Transport Coefficients During Drying of Wood

Moisture transport dynamics in wood during drying studied by long-wave near-infrared hyperspectral imaging

Simulation of drying stresses in wood

Contact Info

Product

Resources

About