Wood drying process: impact on Scots pine lumber durability

Sehlstedt-Persson, Margot; Wamming, Thomas

doi:10.1007/s10086-009-1066-9

Cited by 15 publications

(12 citation statements)

References 19 publications

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“…The above observations imply that the impact of the extraction process is insignificant on the dielectric properties of the Slash pine wood species. However, the density has a greater impact than any of the other factors in the wood species . From the present study, it can be concluded that the effect of extractives and minerals in the wood species is trivial at higher frequencies.…”

Section: Resultsmentioning

confidence: 49%

Dielectric Properties of Typical Australian Wood-Based Biomass Materials at Microwave Frequency

Ramasamy

Moghtaderi

2010

Energy Fuels

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Recent progress in microwave characterization of wood based materials has created a need for better understanding of dielectric properties of these materials, which influence the absorption of electromagnetic energy. In the present study the dielectric measurements were carried out for typical Australian wood species such as Slash pine (Pinus elliottii, a softwood species), and Spotted gum (Eucalyptus maculata, a hardwood species), based on Von Hippel's transmission line method. The influence of extractive removal was also studied and compared with the virgin wood samples. Measurements were performed at 9.47 GHz for both virgin and extractive-free wood samples. Experiments were carried out at atmospheric pressure under a range of ambient temperatures between 20 and 25 °C. The dielectric properties of wood species were determined as a function of controlling factors such as density, moisture content, and fiber directions. Moisture content varied from 0% to 13% for virgin wood samples at atmospheric equilibrium conditions. Results indicated that the dielectric properties of both wood species were affected by density, moisture content, and fiber directions. In general, for virgin wood samples, the dielectric property was found to increase with density and moisture content. The values of the dielectric property in parallel direction to the stem were generally higher than those in the perpendicular direction for virgin sample of both wood species. However, such a trend was not observed for extractive-free wood samples.

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Section: Resultsmentioning

confidence: 49%

Dielectric Properties of Typical Australian Wood-Based Biomass Materials at Microwave Frequency

Ramasamy

Moghtaderi

2010

Energy Fuels

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“…The higher FC determined phenolic content in upper layer of air-dried boards could be favoured by dissolution in products of lipophilic origin which will migrate to wood surface [ 2 ]. The chemical changes such as oxidation of unsaturated fatty acids and natural degradation of resins during air-drying of wood occurs mainly due to that water is evaporated [ 1 ]. The evaporation of water changes also the physiological conditions of the timber cell walls and lower metabolic activity with time.…”

Section: Resultsmentioning

confidence: 99%

“…Drying and especially thermal modification influence the presence and structure of the constituents of the wood material, and subsequently the characteristics and service-life of the final wood products. During drying, complex changes in the properties of wood occur, initiated by heat and mass flows towards the wood surfaces and by degradation of wood constituents [ 1 ]. One mechanism is a migration of non-structural wood-cell compounds such as polar and non-polar extractives.…”

Section: Introductionmentioning

confidence: 99%

Distribution of low-molecular lipophilic extractives beneath the surface of air- and kiln-dried Scots pine sapwood boards

et al. 2018

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During industrial wood drying, extractives migrate towards the wood surfaces and make the material more susceptible to photo/biodegradation. The present work provides information about the distribution, quantity and nature of lipophilic substances beneath the surface in air- and kiln-dried Scots pine (Pinus sylvestris L.) sapwood boards. Samples were taken from knot-free sapwood surfaces and the composition of lipophilic extractives, phenols and low-molecular fatty/resin acids layers at different nominal depths below the surface was studied gravimetrically, by UV-spectrometry and by gas chromatography-mass spectrometry (GC-MS). The concentration of total extractives was significantly higher in kiln-dried than in air-dried samples and was higher close to the surface than in the layers beneath. The scatter in the values for the lipophilic extractives was high in both drying types, being highest for linoleic acid and slightly lower for palmitic, oleic and stearic acids. The amount of fatty acids was low in kiln-dried boards, probably due to a stronger degradation due to the high temperature employed. The most abundant resin acid was dehydroabietic acid followed by pimaric, isopimaric, and abietic acids in both drying types. It is concluded that during kiln-drying a migration front is created at a depth of 0.25 mm with a thickness of about 0.5 mm.

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“…The heat transfer mechanisms described in the literature during conventional drying (Krischer and Kröll 1959;Janik 1965;Häussler 1973;Shottafer and Shuler 1974;Krischer and Kast 1978;Vigants et al 2015), based on energy balance, are used to determine the heat energy demand of a dryer, where the temperature of the humid air as the drying medium does not exceed 100 °C. On the basis of these mechanisms, numerous mathematical models were developed to estimate heat consumption of the drying process (Anderson 1955;Shottafer and Shuler 1974;Ressel 1987;Čiegis and Starikovičus 2002;Elustondo and Oliveira 2009;Anderson and Westerlund 2012;Babich and Snopkov 2012), to optimize the drying process and the stress prediction model (Lessard 1978;Korkut et al 2013). None of these models is applicable when the temperature of the drying medium exceeds 100 °C at atmospheric pressure.…”

Section: Introductionmentioning

confidence: 99%

Mathematical model of the energy consumption calculation during the pine sawn wood (Pinus sylvestris L.) drying process

et al. 2021

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The article presents a modification of the existing mathematical model to calculate energy consumption during conventional drying process. Apart from energy consumption, the model permits to estimate the time of high-temperature drying process. The drying medium is air and superheated steam mixture. The obtained calculation results were compared with conducted experimental tests of drying square-edged sawn sapwood timber (Pinus sylvestris L.). The pine sawn wood samples were dried according to three different drying modes, namely mild, normal and intense. The experiments were performed in a semi-industrial scale drying chamber. On the basis of the experimental research available, existing mathematical models of drying wood have been improved. The developed model included the following changes: a different drying time for each mode and type of drying medium (moisturized air or air and superheated steam mixture). The use of an intensive drying mode significantly reduced the drying process time. The developed mathematical model revealed that the energy consumption of the drying process increases with the intensity of the mode used.

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Wood drying process: impact on Scots pine lumber durability

Cited by 15 publications

References 19 publications

Dielectric Properties of Typical Australian Wood-Based Biomass Materials at Microwave Frequency

Dielectric Properties of Typical Australian Wood-Based Biomass Materials at Microwave Frequency

Distribution of low-molecular lipophilic extractives beneath the surface of air- and kiln-dried Scots pine sapwood boards

Mathematical model of the energy consumption calculation during the pine sawn wood (Pinus sylvestris L.) drying process

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