Thermal behaviour of Norway spruce and European beech in and between the principal anatomical directions
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Walter Sonderegger
,
Stefan Hering
Abstract
Thermal conductivity (ThCond), thermal diffusivity and heat capacity of Norway spruce (Picea abies [L.] Karst.) and European beech (Fagus sylvatica L.) have been determined for all principal directions – radial (R), tangential (T) and longitudinal (L) – depending on the moisture content (MC) and ThCond was additionally measured in 15° steps between these directions. The ThCond was determined in a guarded hot plate apparatus. For determining thermal diffusivity and heat capacity, the same apparatus was supplemented with thermocouples and the temperature evolution was evaluated numerically by a partial differential equation. The results show expectedly that ThCond increases with increasing MC, whereby the highest increment was observed in T and the lowest in L direction. ThCond is higher for beech than for spruce in all anatomical directions and the conductivity for both species is more than twice as high in L direction than perpendicular to grain. The highest ThCond is found for beech at a grain angle of approximately 15°. The lowest ThCond shows spruce at an angle of approximately 60° between T and R direction. Thermal diffusivity is similar for both species and decreases with increasing MC. Its differences with regard to the anatomical directions correlate with those of the ThCond values. Heat capacity is lower for beech than for spruce and shows a clear increase with increasing MC.
©2011 by Walter de Gruyter Berlin New York
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Articles in the same Issue
- Publisher’s Note
- Publisher’s Note
- ORIGINAL ARTICLES
- Brightness reversion of eucalyptus kraft pulp: Effect of carbonyl groups generated by hypochlorous acid oxidation
- MgSO4 vs. Mg(OH)2 as a cellulose protector in oxygen delignification
- Hydrogen peroxide and supercritical carbon dioxide: a new bleaching stage for Eucalyptus kraft-O2 pulps
- Preparation and physical characterization of strongly swellable oligo(oxyethylene) lignin hydrogels
- Activation of pine kraft lignin by Fenton-type oxidation for cross-linking with oligo(oxyethylene) diglycidyl ether
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- Theory of transport processes in wood below the fiber saturation point. Physical background on the microscale and its macroscopic description
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- Aging of wood: Analysis of color changes during natural aging and heat treatment
- Thermal behaviour of Norway spruce and European beech in and between the principal anatomical directions
- Air-coupled ultrasound inspection of glued laminated timber
- Optical characteristics of wood investigated by time-of-flight near infrared spectroscopy
- Comparison of NDE techniques for assessing mechanical properties of unjointed and finger-jointed lumber
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- FT-IR imaging microscopy to localise and characterise simultaneous and selective white-rot decay within spruce wood cells
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