Abstract
Pinus radiata sapwood boards of 100 × 40 × 1200 mm were dried in a tube dryer at Luleå University, using a computer tomography (CT) scanner to scan the wood during drying. The CT-scanned wet wood density can illustrate moisture distribution within wood when the wood basic density profile is known. The CT-scanned results were used to validate a 2-D single board drying model developed at the New Zealand Forest Research Institute. The validation has shown that the model is not only capable of predicting the average moisture content but also moisture content gradients in board thickness, width and within growth rings. To investigate the effects of sawing pattern and intrinsic wood properties on drying, the input parameters for the model include within-ring variations of wood density, green moisture content and wood permeability. The model can assist in understanding the causes of some drying defects and has potential for the development of drying schedules.
Zusammenfassung
Splintholzbretter vonPinus radiata (100 × 40 × 1200 mm) wurden getrocknet, wobei gleichzeitig mittels Computertomographie die Holzfeuchte verfolgt wurde. Die dabei erfaßte Dichteverteilung kann als Feuchteverteilung dargestellt werden, wenn das entsprechende Rohdichteprofil des Holzes bekannt ist. Die ermittelten Daten wurden verwendet um ein zweidimensionales Modell zu verifizieren, das am Holzforschungsinstitut in Neuseeland entwickelt worden ist. Es ergab sich, daß dieses Modell nicht nur die durchschnittliche Holzfeuchte richtig vorhersagt, sondern auch Feuchtegradienten innerhalb des Brettes und zwar gemessen über die Breite, die Dicke und innerhalb der Jahrringe. Um die Einflüsse der Schnittparameter und der Holzeigenschaften zu untersuchen, enthält das Modell auch Angaben über Dichteverteilungen innerhalb der Jahrringe, die Ausgangsfeuchte und Durchlässigkeit des Holzes. Das Modell hilft auch zum Verständnis einiger Trocknungsfehler und ermöglicht die Entwicklung von Trocknungsfahrplänen
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This work is supported by the New Zealand Foundation of Research, Science and Technology under contract C04415 and Kempestiftelserna 891 80 rnskldsvik, re. JCK 1-9602.
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Pang, S., Wiberg, P. Model predicted and CT scanned moisture distribution in aPinus radiata board during drying. Holz als Roh-und Werkstoff 56, 9–14 (1998). https://doi.org/10.1007/s001070050256
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DOI: https://doi.org/10.1007/s001070050256