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Experimental investigation of jet drying of birch and spruce veneers and modelling with a simplified approach

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Abstract

The paper presents experimental results of jet drying tests of birch ( Betula pendula) and spruce ( Picea abies) veneers at temperatures of 140°C and 190°C. Results include drying rates for 1.5 mm thick birch veneers as well as 1.5 mm and 2.6 mm thick spruce veneers of both heartwood and sapwood. Based on the test results, material parameter values for a simplified drying model are assessed. The model is based on the use of an effective diffusion coefficient and an effective surface emission coefficient, which values are calibrated to fit to the experimental results. It is observed, that separate model parameter sets are needed for the two different species but also for occurrence of heartwood or sapwood (spruce) and different thickness values of veneers.

Zusammenfassung

Das Manuskript stellt experimentelle Ergebnisse von Schnelltrocknungstests bei Birken- und Fichtenfurnier vor, bei Temperaturen zwischen 140°C und 190°C. Die Ergebnisse beinhalten Trocknungsraten für 1,5 mm dickes Birken- sowie 1,5 bis 2,6 mm dickes Fichtenfurnier sowohl von Kern- als auch von Splintholz. Basierend auf den Testergebnissen wurden materielle Parameterwerte für ein vereinfachtes Trocknungsmodell geschätzt. Das Modell basiert auf der Verwendung eines effektiven Diffusionskoeffizienten sowie auf einem effektiven Oberflächen-Emissionskoeffizienten, dessen Werte jeweils kalibriert werden, um sie den experimentellen Werten anzupassen. Es wurde beobachtet, dass getrennte Modell-Parameter-Sets für die beiden verschiedenen Holzarten benötigt werden und ebenso für das Vorkommen von Kern- und Splintholz (Fichte) und die verschiedenen Dichtewerte von Furnierholz.

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Fig. 1a–d. Abb. 1a–d.
Fig. 2a–d. Abb. 2a–d.
Fig. 3a–e. Abb. 3a–e.

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Authors and Affiliations

  1. VTT Building and Transport, Puumiehenkuja 2A, P.O.Box 1806, 02044, Espoo, Finland

    A. Hanhijärvi

  2. Valutec Oy, Pitkämäenkatu 11A, P.O.Box 43, 20251, Turku, Finland

    A. Hukka

  3. Laboratory of Wood Technology, Helsinki University of Technology, Puumiehenkuja 2B, P.O.Box 5100, 02015, Espoo, Finland

    T. Paajanen, P. Pulkkinen & S. Sundman

Authors
  1. A. Hanhijärvi
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  2. A. Hukka
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  3. T. Paajanen
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  4. P. Pulkkinen
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  5. S. Sundman
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Corresponding author

Correspondence to A. Hanhijärvi.

Additional information

The authors would like to express their gratitude for the financial support of the National Technology Agency of Finland, Raute Wood Ltd. and Finnish Wood Research Ltd. in the project "Veneer drying—the influence of wood material and drying process on product properties". In addition, AHa would like to acknowledge the support of the Academy of Finland in the project "Modelling or novel drying techniques of wood".

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Hanhijärvi, A., Hukka, A., Paajanen, T. et al. Experimental investigation of jet drying of birch and spruce veneers and modelling with a simplified approach. Holz Roh Werkst 61, 83–88 (2003). https://doi.org/10.1007/s00107-003-0379-4

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  • DOI: https://doi.org/10.1007/s00107-003-0379-4

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