An improved drying model for highly-impermeable hardwoods

Herritsch, Alfred; Nijdam, J. J.

doi:10.1515/hf.2009.075

Cited by 7 publications

(20 citation statements)

References 2 publications

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“…Scientific and technological efforts to improve drying are as old as wood science, but there are still many challenges as demonstrated by the recent literature. Herritsch and Nijdam (2009) suggested an improved drying model for highly impermeable hardwoods. Junior et al (2010) reported on nonsymmetrical drying tests for the assessment of drying behavior of a hardwood difficult to dry.…”

Section: Introductionmentioning

confidence: 99%

Experimental and finite element study of the effect of temperature and moisture on the tangential tensile strength and fracture behavior in timber logs

Larsen

Ormarsson

2013

Holzforschung

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Timber is normally dried by kiln drying, in the course of which moisture-induced stresses and fractures can occur. Cracks occur primarily in the radial direction due to tangential tensile strength (TSt) that exceeds the strength of the material. The present article reports on experiments and numerical simulations by finite element modeling (FEM) concerning the TSt and fracture behavior of Norway spruce under various climatic conditions. Thin log disc specimens were studied to simplify the description of the moisture flow in the samples. The specimens designed for TS were acclimatized to a moisture content (MC) of 18% before TSt tests at 20°C, 60°C, and 90°C were carried out. The maximum stress results of the disc simulations by FEM were compared with the experimental strength results at the same temperature levels. There is a rather good agreement between the results of modeling and experiments. The results also illustrate the strong decrease of TSt with increasing temperature at a constant MC level.

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Section: Introductionmentioning

confidence: 99%

Experimental and finite element study of the effect of temperature and moisture on the tangential tensile strength and fracture behavior in timber logs

Larsen

Ormarsson

2013

Holzforschung

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“…The rationale is that the drying rate is likely controlled by moisture diffusion through wood shells, where the MC is below the FSP. The Fickian approach was attractive for the modelling due to its simplicity and ease of numerical solution (Herritsch and Nijdam 2009). Therefore, the diffusive model is suitable for describing the moisture transfer from inside to outside the board.…”

Section: Determination Of Effective Diffusion Coefficientsmentioning

confidence: 99%

“…Herritsch and Nijdam (2009) developed a drying model that includes both the temperature and MC effects on the diffusion coefficient for highly impermeable hardwoods. Using Matlab 7.0, the coupled partial-differential equations were solved.…”

Section: Introductionmentioning

confidence: 99%

Modeling the Air-drying Rate of Chinese Larch Lumber

Hua

Cai

2016

BioResources

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To help protect the environment and reduce energy consumption in the wood industry, air-drying has been used to pre-dry lumber to about 30% moisture content. An air-drying model based on the principle of diffusivity was developed to help estimate air-drying times more accurately. Because the moisture movement rate considerably differs from that which occurs during kiln drying, the effective diffusion coefficients were experimentally determined at different temperatures. A user-friendly computer program predicting air-drying times was developed using the control volume method. The model was experimentally confirmed by air-drying practices. This program is a powerful tool used to estimate the air-drying times for any final moisture content for larch lumber, at any time of the year, at any location where the historical meteorological data, such as temperature, relative humidity, and wind speed, is available. This tool enables mill managers to generate an optimal operation plan based on their kiln capacity, yard availability, inventory requirements, and weather conditions.

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“…Three different models (model based on Lui kov's approach, diffusion model, and multiphase model) were developed and compared for high temperature drying by Kocaefe et al (2007); but the comparison was limited in drying below fiber saturation point (FSP). Herritsch and Nijidam (2009) proposed an improved drying model for highly-impermeable hardwoods in which MC, temperature, and diffusion coefficient were taken into consideration for drying model development for various timber thicknesses under different drying conditions. Zhu and Kaliske (2011) discussed the interrelationship between temperature, MC, and gas pressure by solving partial differential equations (PDEs) under Neumann boundary conditions for both temperature and MC and Dirichlet boundary condition for gas pressure.…”

Section: Introductionmentioning

confidence: 99%

Mathematical modeling of drying of Masson pine lumber and its asymmetrical moisture content profile

et al. 2013

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A mathematical model is discussed in terms of moisture transfer during the drying process of Masson pine (Pinus massoniana) lumber in industrial practice. The model was validated by comparing the simulated result of moisture distribution with experimental data. In the model, the wood drying process was divided into two phases. The first one dealt with processes above fiber saturation point (FSP), that was driven by capillary flux of free water and conductive flux of vapor, and the second one dealt with those of below FSP, which was driven by diffusive flux of bound water and vapor. Moisture content distribution (MC D ) inside wood is simulated by solving a parabolic partial differential equation under Dirichlet boundary conditions. The moisture content profile (MC P ) was asymmetrical in experiments, and the simulation result agreed well with the experiments. An easy empirical formulation was also proposed to calculate real wood permeability, as it showed general characteristics of liquid and vapor permeability. This permeability model is verified as the cause of asymmetrical MC P in this paper.

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An improved drying model for highly-impermeable hardwoods

Cited by 7 publications

References 2 publications

Experimental and finite element study of the effect of temperature and moisture on the tangential tensile strength and fracture behavior in timber logs

Experimental and finite element study of the effect of temperature and moisture on the tangential tensile strength and fracture behavior in timber logs

Modeling the Air-drying Rate of Chinese Larch Lumber

Mathematical modeling of drying of Masson pine lumber and its asymmetrical moisture content profile

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