NMR imaging of fluid pathways during drainage of softwood in a pressure membrane chamber

Almeida, Giana; Leclerc, Sébastien; Perré, Patrick

doi:10.1016/j.ijmultiphaseflow.2007.10.009

Cited by 43 publications

(26 citation statements)

References 25 publications

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“…By employing CPMG sequences, relaxation spectra from different parts of the wood structure can be analysed. This has been done on both annual ring level (Dvinskikh et al 2011;Quick et al 1990) and cell level (Almeida et al 2008;Hernandez and Caceres 2010;Meder et al 2003;Passarini et al 2015), allowing a visualisation of water distributions in both the hygroscopic (Hernandez and Caceres 2010;Passarini et al 2015) and over-hygroscopic RH range (Almeida et al 2008). MR imaging is mainly appropriate for water with longer relaxation times than bound water (Hernandez and Caceres 2010).…”

Section: Spectroscopic Techniquesmentioning

confidence: 99%

Experimental techniques for characterising water in wood covering the range from dry to fully water-saturated

2017

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Water plays a central role in wood research, since it affects all material properties relevant to the performance of wood materials. Therefore, experimental techniques for characterising water within wood are an essential part of nearly all scientific investigations of wood materials. This review focuses on selected experimental techniques that can give deeper insights into various aspects of water in wood in the entire moisture domain from dry to fully water-saturated. These techniques fall into three broad categories: (1) gravimetric techniques that determine how much water is absorbed, (2) fibre saturation techniques that determine the amount of water within cell walls, and (3) spectroscopic techniques that provide insights into chemical wood-water interactions as well as yield information on water distribution in the macro-void wood structure. For all techniques, the general measurement concept is explained, its history in wood science as well as advantages and limitations.

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Section: Spectroscopic Techniquesmentioning

confidence: 99%

Experimental techniques for characterising water in wood covering the range from dry to fully water-saturated

2017

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“…The MR imaging technique has been proven effective in studying moisture content distribution in wood (Quick et al 1990;Meder et al 2003;Hameury and Sterley 2006;Almeida et al 2008;Dvinskikh et al 2011;Telkki 2012). As the moisture content, that is 1 H concentration, decreases, the signal intensity will be lower.…”

Section: Introductionmentioning

confidence: 99%

Distribution of the equilibrium moisture content in four hardwoods below fiber saturation point with magnetic resonance microimaging

2015

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The distribution of liquid and bound water in wood samples under equilibrium moisture contents (EMC) below fiber saturation point (FSP) was assessed by magnetic resonance (MR) microimaging. Two Amazonian hardwoods, huayruro (Robinia coccinea) and cachimbo [Cariniana domesticata], a plantation grown eucalyptus (Eucalyptus saligna), and a temperate species red oak (Quercus rubra) were studied. Desorption tests were performed at 21°C from full saturation state for huayruro, cachimbo, and red oak, and from green condition for eucalyptus. The EMC was reached under three desorption conditions [58, 76, and 90 % relative humidity (RH)]. MR microimages were obtained based on T 2 times and on 1 H concentration. Scanning electron microscopy images helped us to interpret MR microimages. The results showed that wood structure plays a major role in liquid water drainage and in water diffusion. Eucalyptus saligna and red oak showed liquid water entrapped in parenchyma tissues, even below FSP (90 % RH). At this same RH level, all liquid water was, however, drained for cachimbo and huayruro. For these woods, bound water was not uniformly distributed in wood structure, concentrating it more in fibers for both species. Huayruro showed the highest heterogeneity in hygroscopicity, which is explained by its particular wood anatomy.

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“…By its ability to focus on water only, NMR imaging (Deurer et al 2002, Almeida et al 2008) is certainly more adapted for this purpose than X-ray tomography (Wiberg and Morén 1999).…”

Section: Discussionmentioning

confidence: 99%

A mesoscopic drying model applied to the growth rings of softwood: mesh generation and simulation results

Perré

Turner

2008

Maderas, Cienc. tecnol.

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A mesoscopic drying model that enables the drying simulation of quartersawn and fl atsawn wood sections consisting of several growth rings is presented. The procedure to generate the virtual board description directly from real sample images is also described. This virtual structure accommodates the prominent sample features, including its geometrical and physical properties, together with the density and structural variation across the growth rings. We give a synopsis of the sophisticated techniques developed specifi cally to generate this virtual description and exhibit the fi nal computational meshes produced by the software for quartersawn and fl atsawn sections. Low temperature drying simulations are then performed for both heterogenous and homogeneous model variants using these virtual descriptions and comparisons are made of the resulting MC fi eld evolution. A highlight of these comparisons is that the heterogeneous model captures realistic drying effects, including the fast drying of earlywood and the late removal of liquid water in latewood. In comparing the drying of quartersawn and fl atsawn boards we conclude that the effect of the heterogeneous nature of the MC fi elds is diminished somewhat when considering the fl atsawn section over the quartersawn section.

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NMR imaging of fluid pathways during drainage of softwood in a pressure membrane chamber

Cited by 43 publications

References 25 publications

Experimental techniques for characterising water in wood covering the range from dry to fully water-saturated

Experimental techniques for characterising water in wood covering the range from dry to fully water-saturated

Distribution of the equilibrium moisture content in four hardwoods below fiber saturation point with magnetic resonance microimaging

A mesoscopic drying model applied to the growth rings of softwood: mesh generation and simulation results

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