Drying model for softwood and moisture patterns measured by magnetic resonance imaging

Sandoval-Torres, Sadoth; Pérez-Santiago, A.; Hernández-Bautista, E.

doi:10.1080/07373937.2018.1457050

Cited by 13 publications

(4 citation statements)

References 33 publications

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“…For wood the possibility of such basic mechanisms has long been studied, but this material has specificities which may make the process more complex [8][9][10][11]: (i) hardwoods, on which we will focus here, contain long vessels but also a large fraction of voids (fibers) whose connection with the sample free surface is tenuous or inexistent, (ii) bound water (adsorbed) in cell walls can diffuse through the solid structure. In this context, by similarity with knowledge of drying in simpler porous media, it has been considered that in a first stage some water (free water in voids) is withdrawn from the sample by capillary forces, while in a second stage drying essentially occurs by diffusion of vapor and/or bound water through the sample [9,[12][13][14][15]. However, the detailed characteristics of these two phases and the conditions of transition between them are not well identified or experimentally proved by internal observations.…”

Section: Introductionmentioning

confidence: 99%

How Bound Water Regulates Wood Drying

et al. 2020

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For most wood-based product uses it is essential to remove a large part of the water content from wet or green (fresh-cut) wood, to reduce further dimensional variations under varying humidity conditions, improve its mechanical characteristics and protect it from biological attacks. However, the internal mechanisms of drying are not fully described. Here we observe drying at different scales using macroscopic measurements (weighing), NMR (Nuclear Magnetic Resonance) measurements allowing to distinguish bound and free water contents, and XRCT (X-ray computed tomography) images of air-liquid interfaces at the smallest pore scale (wood lumens). We show that during wood drying, even well above the Fiber Saturation Point, bound water diffusion in cell walls (instead of capillary effects) ensures the extraction of liquid water from pores and its transport towards the surface of evaporation, and thus controls the drying rate. The distribution of bound water content (uniform or heterogeneous) along the main sample axis and the drying rate evolution depend on the competition between the external conditions and a characteristic rate of transport due to bound water diffusion. For sufficiently slow drying this distribution remains homogenous until free water is fully extracted. An original physical phenomenon is thus at work which plays a major role of regulation of water extraction, in that it maintains a constant drying rate and a homogeneous distribution of the (mean) water content throughout the material. These results provide sound concepts for modeling and controlling drying properties of wood materials. They open the way to the understanding or control of the properties of many other materials containing two water types in food or civil engineering applications. Our results complete recent observations that bound water diffusion also controls imbibition in hardwood and finally show that transfers between bound and free water play a major role in the interaction of plant-like systems with water.

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Section: Introductionmentioning

confidence: 99%

How Bound Water Regulates Wood Drying

et al. 2020

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“…Furthermore, a variant in which the exponent of the relative permeability is reduced from 3 to 2 is analyzed. As shown in Example m, when modeling the drying experiment from [16], this adjustment led to a slightly better agreement with the test results.…”

Section: Model Validationmentioning

confidence: 94%

Numerical modeling in timber engineering – moisture transport and quasi-brittle failure

Eberhardsteiner,

Pech,

Autengruber

et al. 2023

Rad Hrvatske akademije znanosti i umjetnosti

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With the rising popularity of timber structures and the increasing complexity of timber engineering projects, the need for numerical simulation tools specific to this building material is gaining rapidly in importance. in particular, moisture transport processes and the quasi-brittle failure behavior, both difficult to describe, present major challenges and are of great relevance in practical construction. For these reasons, this article presents numerical modeling concepts for predicting moisture gradients, estimating effective stiffness and strength, and numerically identifying potential cracking mechanisms in wooden components. These concepts are validated through experimental test programs, and the associated challenges are addressed. selected results ultimately demonstrate the capabilities and relevance of such methods for timber engineering.

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“…Auch bei der Trocknungssimulation von [15], die in Beispiel ③ untersucht wird, kann eine gute Übereinstimmung festgestellt werden. Zusätzlich wird eine Variante, bei der der Exponent der relativen Permeabilität von 3 auf 2 reduziert wird, verglichen, was, wie auch bei Beispiel ④ bei der Modellierung des Trocknungsexperiments aus [16], zu einer geringfügig besseren Übereinstimmung mit den Versuchsergebnissen führte.…”

Section: Finite‐elemente‐basiertes Simulationskonzeptunclassified

Computergestützte Modellierung von Feuchtetransportprozessen in Holzwerkstoffen

et al. 2022

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Dieser Beitrag präsentiert computergestützte Modellierungskonzepte zur Vorhersage von Feuchteverläufen und zugehörigen Spannungsfeldern sowie zur numerischen Bestimmung potenzieller Risstiefen von Holzbauteilen. Die vorgestellten Konzepte werden anhand experimenteller Versuchsprogramme validiert und die damit einhergehenden Herausforderungen diskutiert. Ausgewählte Ergebnisse zeigen letztendlich die Möglichkeiten und auch die Relevanz solcher Methoden für den Ingenieurholzbau auf.

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Drying model for softwood and moisture patterns measured by magnetic resonance imaging

Cited by 13 publications

References 33 publications

How Bound Water Regulates Wood Drying

How Bound Water Regulates Wood Drying

Numerical modeling in timber engineering – moisture transport and quasi-brittle failure

Computergestützte Modellierung von Feuchtetransportprozessen in Holzwerkstoffen

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