NMR imaging study and multi-Fickian numerical simulation of moisture transfer in Norway spruce samples

Dvinskikh, Sergey V.; Henriksson, Marielle; Mendicino, Antonio Lorenzo; Fortino, Stefania; Toratti, Tomi

doi:10.1016/j.engstruct.2011.04.011

Cited by 34 publications

(26 citation statements)

References 17 publications

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“…Lignin is hydrophobic, whereas cellulose and hemicellulose are hydrophilic. This coexistence and the multitude of different softening reactions due to water explain why the mechanical properties of wood are strongly dependent of water content [8]. In fresh Norway spruce, the moisture content, defined here as water mass to dry mass ratio, is about 50 % in heart wood and 130 % in sap wood.…”

Section: Introductionmentioning

confidence: 99%

“…Particle methods are able to describe the complex geometries and include contacts also between not neighboring points [17]. However, the advanced FEM algorithms, which exploit both constitutive and geometrical nonlinear behavior, enable the analysis of wood cell deformations for a wider repertory like complex loading and boundary conditions and coupled hygro-thermomechanical analyses (see [8] and related references). A first version of such a method is introduced in the present paper.…”

Section: Introductionmentioning

confidence: 99%

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A 3D micromechanical study of deformation curves and cell wall stresses in wood under transverse loading

et al. 2014

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The deformation of wood is analyzed using the finite element method to quantify the phenomena in wood cells and cell walls. The deformation curves of computed microstructures are compared to experimental observations in two different loading cases: compression and combination of shear and compression. Simulated and experimental shapes of deformation curves match qualitatively and the deformation shapes exhibit a similar response to change in the loading mode. We quantify the intra-cell-wall stresses to understand the effects of the different layers during the deformation. The results benefit the development of energy efficient mechanical and chemo-mechanical pulping processes for pulp, board, and composite manufacture. In addition, the aspects of cell deformation can be exploited to dismantle the wood to accelerate chemical reactions in biorefinery.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A 3D micromechanical study of deformation curves and cell wall stresses in wood under transverse loading

et al. 2014

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“…A main drawback of X-ray radiography is the limited resolution in quantifying the water content. Magnetic resonance imaging (MRI) is another imaging approach that has been used to visualize the spatial change of moisture content in wood [14][15][16]. Although spatial resolution reaches 78 m, the moisture resolution of MRI, while higher than X-ray radiography, lies between 2-4 kg/m 3 [15,16], thus may not capture small variations of moisture content.…”

Section: Introductionmentioning

confidence: 99%

Visualization and quantification of liquid water transport in softwood by means of neutron radiography

Sedighi-Gilani

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Mannes

et al. 2012

International Journal of Heat and Mass Transfer

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“…NMR Imaging has been proven to be an excellent tool to determine the distribution and the concentration of water in wood during drying (Quick et al 2007;Stenström et al 2014;Dvinskikh et al 2011a, b), and during uptake (Robertson and Packer 1999;Van Meel et al 2011;Donkers et al 2013). In situ determination of local moisture content has been achieved by portable NMR devices (Casieri et al 2004;Dvinskikh et al 2011b). Another important advantage of NMR over other methods is its ability to distinguish between bound and free water by relaxation analysis (T 2 ), i.e.…”

Section: Introductionmentioning

confidence: 99%

Bound and free water distribution in wood during water uptake and drying as measured by 1D magnetic resonance imaging

et al. 2016

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Knowledge on moisture transport in wood is important for understanding its utilization, durability and product quality. Moisture transport processes in wood can be studied by Nuclear Magnetic Resonance (NMR) imaging. By combining NMR imaging with relaxometry, the state of water within wood can be identified, i.e. water bound to the cell wall, and free water in the cell lumen/vessel. This paper presents how the transport of water can be monitored and quantified in terms of bound and free water during water uptake and drying. Three types of wood from softwood to hardwood were selected covering a range of low to high density wood; pine sapwood and oak and teak. A calibration is performed to determine the different water states in each different wood type and to convert the NMR signal into moisture content. For all wood types, water transport appeared to be internally limited during both uptake and drying. In case of water uptake, free water was observed only after the cell walls were saturated with bound water. In case of drying, the loss of bound water starts only after vanishing of free water, irrespective of the position. Obviously, there is always a local thermodynamic equilibrium of bound and free water for both uptake and drying. Finally, we determined the effective diffusion coefficient (D eff ). Experimentally determined diffusion constants were compared with those derived by the diffusion models for conceptual understanding of transport mechanism. We found that diffusion in the cell wall fibers plays a critical role in the transport process.

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NMR imaging study and multi-Fickian numerical simulation of moisture transfer in Norway spruce samples

Cited by 34 publications

References 17 publications

A 3D micromechanical study of deformation curves and cell wall stresses in wood under transverse loading

A 3D micromechanical study of deformation curves and cell wall stresses in wood under transverse loading

Visualization and quantification of liquid water transport in softwood by means of neutron radiography

Bound and free water distribution in wood during water uptake and drying as measured by 1D magnetic resonance imaging

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