Skip to content
Licensed Unlicensed Requires Authentication Published by De Gruyter August 10, 2013

Measured temperature and moisture profiles during thermal modification of beech (Fagus sylvatica L.) and spruce (Picea abies L. Karst.) wood

  • Petr Čermák EMAIL logo , Petr Horáček and Peter Rademacher
From the journal Holzforschung


The temperature and moisture profiles during thermal modification of beech (Fagus sylvatica L.) and spruce (Picea abies L. Karst.) wood have been investigated. Specimens with dimensions of 80×80×200 mm3 were heat treated based on ThermoWood technology. Heat transfer was continuously measured by several thermocouples placed into various positions of the samples. In the course of the treatment, samples were removed from the chamber at different times, and their moisture content (MC) was measured by the so-called slicing technique. The complete data of heat and moisture movement during the heat treatment process are presented. Significant temperature gradients occur in the initial and modification stages of the process. In the latter, the chamber temperature was 200°C for 3 h, but exothermic reaction increased the sample temperatures to 240°C (beech) and 215°C (spruce). Thermodiffusion (Soret effect) at the beginning of the process was observed. Therefore, the MC under surfaces (in transverse and in longitudinal direction) was increasing ∼0.5%–3% for 5 h. The results provide a better insight into details of thermal modification of wood.

Corresponding author: Petr Čermák, Faculty of Forestry, and Wood Technology, Department of Wood Science, Mendel University in Brno, Zemědělská 3, 613 00 Brno, Czech Republic, Phone: +420 545 134 550, e-mail:

The authors are grateful to reviewers, who helped in clarifying this article. The authors are also grateful to KATRES Company, especially to Karel Slimáček, for the assistance during experiments. This work was funded by the European Social Fund and the state budget of the Czech Republic (project “The Establishment of an International Research Team for the Development of New Wood-Based Materials”, reg. no. CZ.1.07/2.3.00/20.0269) and by the Internal Grant Agency (IGA) of the Faculty of Forestry and Wood Technology, Mendel University in Brno (Project No. 26/2012).


Atreya, A. Pyrolysis, Ignition, and Flame Spread on Horizontal Surfaces of Wood. PhD thesis. Harvard University, Cambridge, MA, 1983.Search in Google Scholar

Avramidis, S., Hatzikiriakos, S.G. (1995) Convective heat and mass transfer in nonisothermal moisture desorption. Holzforschung 49:163–167.10.1515/hfsg.1995.49.2.163Search in Google Scholar

Avramidis, S., Hatzikiriakos, S.G., Siau, J.F. (1994) An irreversible thermodynamics model for unsteadystate nonisothermal moisture diffusion in wood. Wood Sci. Technol. 28:349–358.Search in Google Scholar

Babiak, M. Wood-Water System. VŠLD, Zvolen, 1990.Search in Google Scholar

Babiak, M. (1996) Temperature profiles in wood. Drevársky Výskum 41:3–14.Search in Google Scholar

Brischke, Ch., Welzbacher, Ch.R., Brandt, K., Rapp, A.O. (2007) Quality control of thermally modified timber: interrelationship between heat treatment intensities and CIE L*a*b* color data on homogenized wood samples. Holzforschung 61:19–22.10.1515/HF.2007.004Search in Google Scholar

Browne, F.L. Theories of the Combustion of Wood and Its Control. Forest Products Laboratory, Madison, WI, 1958.Search in Google Scholar

Bryden, K.M. Computation Modeling of Wood Combustion. PhD thesis. University of Wisconsin, Madison, WI, 1998.Search in Google Scholar

Bučar, B., Straže, A. (2007) Determination of the thermal conductivity of wood by the hot plate method: the influence of morphological properties of fir wood (Abies alba Mill.) to the contact thermal resistance. Holzforschung 62:362–367.Search in Google Scholar

Cai, Z. (2007) Determining moisture gradient profile using x-ray technique. In: Proceedings of 15th International Symposium on Nondestructive Testing of Wood, September 10–13, Duluth, MN.Search in Google Scholar

Cai, Z. (2008) A new method of determining moisture gradient in wood. Forest Prod. J. 58:41–45.Search in Google Scholar

Čermák, P., Trcala, M. (2012) Influence of uncertainty in diffusion coefficients on moisture field during wood drying. Int. J. Heat Mass Transfer 55:7709–7717.10.1016/j.ijheatmasstransfer.2012.07.070Search in Google Scholar

Dubey, M.K., Pang, S., Walker, J. (2011) Changes in chemistry, color, dimensional stability and fungal resistance of Pinus radiata D. Don wood with oil heat-treatment. Holzforschung 66:49–57.Search in Google Scholar

Esteves, B.M., Pereira, H.M. (2009) Wood modification by heat treatment a review. BioRes. 4:370–404.10.15376/biores.4.1.EstevesSearch in Google Scholar

Finnish ThermoWood Association. ThermoWood Handbook, Helsinki, Finland, 2003.Search in Google Scholar

Gryc, V., Vavrčík, H., Gomola, Š. (2008) Selected properties of European beech (Fagus sylvatica L.). J. For. Sci. 54:418–425.Search in Google Scholar

Gryc, V., Horáček, P., Šlezingerová, J., Vavrčík, H. (2011) Basic density of spruce wood, wood with bark and bark of branches in locations in the Czech Republic. Wood Res. Slovakia 56:23–32.Search in Google Scholar

Hattori, Y., Kanagawa, Y. (1985) Nondestructive measurement of moisture distribution in wood with a medical x-ray CT scanner I. Accuracy and influencing factor. J. Japan Wood Res. Soc. 31:974–982.Search in Google Scholar

Hongmei, G. Structure Based, Two-Dimensional Anisotropic, Transient Heat Conduction Model for Wood. PhD thesis. Faculty of the Virginia Polytechnic Institute, Blacksburg, VA, 2001.Search in Google Scholar

Horáček, P. (2003) Modeling of coupled moisture and heat transfer during wood drying. In: IUFRO Wood Drying Conference. Transilvania University of Brasov, Brasov, Romania. pp. 372–378.Search in Google Scholar

Johanson, A., Fhyr, C., Rasmuson, A. (1997) High temperature convective drying of wood chips with air and superheated steam. Int. J. Heat Mass Transfer 40:2843–2858.10.1016/S0017-9310(96)00341-9Search in Google Scholar

Johansson, D., Moren, T. (2005) The potential of colour measurement for strength prediction of thermally treated wood. Holz Roh Werkst. 64:104–110.10.1007/s00107-005-0082-8Search in Google Scholar

Kim, D., Nishiyama, Y., Wada, M., Kuga S., Okano, T. (2005) Thermal decomposition of cellulose crystallites in wood. Holzforschung 55:521–524.10.1515/HF.2001.084Search in Google Scholar

Kubler, H., Wang, Y.R., Barkalow, D. (2009) Generation of heat in wood between 80 and 130°C. Holzforschung 39:85–89.10.1515/hfsg.1985.39.2.85Search in Google Scholar

Li, X.J., Zhang, B.G., Li, W.J. (2005) Research on thermal diffusion in wood. In: Proceedings of 9th International Conference IUFRO Wood Drying, August 21–26, Nanjing, China. pp. 95–100.Search in Google Scholar

Li, X.J., Zhang, B, Li, W., Li, Y. (2006) Nonisothermal moisture movement in wood. Front. For. China 1:348–352.Search in Google Scholar

Liu, J., Avramidis, S., Ellis, S. (2009) Simulation of heat and moisture transfer in wood during drying under constant ambient conditions. Holzforschung 48:236–240.10.1515/hfsg.1994.48.3.236Search in Google Scholar

Martinović, D., Horman, I., Demirdzic, I. (2001) Numerical and experimental analysis of wood drying process. Wood Sci. Technol. 35:143–156.Search in Google Scholar

Militz, H. (2002) Heat treatment of wood: European processes and their background. In: Proceedings of Conference on Enhancing the Durability of Lumber and Engineered Wood Products, February 11–13, Kissimmee, Orlando, FL.Search in Google Scholar

Miller, R.S., Bellan, J. (1996) A generalized biomass pyrolysis model based on superimposed cellulose, hemicellulose and lignin kinetics. Combust. Sci. Technol. 126:97–137.Search in Google Scholar

Nabhani, N., Tremblay, C., Fortin, Y. (2003) Experimental determination of convective heat and mass transfer coefficients during wood drying. In: IUFRO Wood Drying Conference. Transilvania University of Brasov, Brasov, Romania. pp. 225–230.Search in Google Scholar

Pang, S. (1997) Relationship between a diffusion model and a transport model for softwood drying. Wood Fiber Sci. 29:58–67.Search in Google Scholar

Rosenkilde, A., Glover, P. (2005) High resolution measurement of the surface layer moisture content during drying of wood using a novel magnetic resonance imaging technique. Holzforschung 56:312–317.10.1515/HF.2002.050Search in Google Scholar

Shafizadeh, F. (1982) Introduction to pyrolysis of biomass. J. Anal. Appl. Pyrol. 3:283–305.10.1016/0165-2370(82)80017-XSearch in Google Scholar

Shafizadeh, F. (1984) The chemistry of pyrolysis and combustion. In: The Chemistry of Solid Wood. Advances in Chemistry Series 207. American Chemical Society, Washington, DC. pp. 489–529.10.1021/ba-1984-0207.ch013Search in Google Scholar

Siau, J.F. (1983) A proposed theory for nonisothermal unsteady-state transport of moisture in wood. Wood Sci. Technol. 17:75–77.Search in Google Scholar

Siau, J.F. Transport Processes in Wood. Springer-Verlag, Berlin, Heidelberg, 1984.10.1007/978-3-642-69213-0Search in Google Scholar

Sivonen, H., Maunu, S.L., Sundholm, F., Jämsä, S., Viitaniemi, P. (2002) Magnetic resonance studies of thermally modified wood. Holzforschung 56:648–654.10.1515/HF.2002.098Search in Google Scholar

Sonderegger, W., Hering, S., Niemz, P. (2011) Thermal behaviour of Norway spruce and European beech in and between the principal anatomical directions. Holzforschung 65:369–375.10.1515/hf.2011.036Search in Google Scholar

Syrjänen, T., Kangas, E. Heat-Treated Timber in Finland. International Research Group Wood Preservation, IRG/WP 00-40158, IRG Secretariat, SE-100, 44 Stockholm, Sweden, 2000.Search in Google Scholar

Tanaka, T., Avramidis, S., Shida, S. (2009) Evaluation of moisture content distribution in wood by soft X-ray imaging. J. Wood Sci. 55:69–73.10.1007/s10086-008-0997-xSearch in Google Scholar

Trcala, M. (2012) A 3D transient nonlinear modeling of coupled heat, mass and deformation fields in anisotropic material. Int. J. Heat Mass Transfer 55:4588–4596.10.1016/j.ijheatmasstransfer.2012.04.009Search in Google Scholar

Vavrčík, H., Gryc, V. (2012) Analysis of the annual ring structure and wood density relations in English oak and Sessile oak. Wood Res. Slovakia 57:573–580.Search in Google Scholar

Vay, O., Obersriebnig, M., Müller, U., Konnerth, J., Altmutter, W.G. (2012) Studying thermal conductivity of wood at cell wall level by scanning thermal microscopy (SThM). Holzforschung 67:155–159.10.1515/hf-2012-0052Search in Google Scholar

Watanabe, K., Saito, Y., Stavros Avramidis, S., Shida, S. (2008) Non-destructive measurement of moisture distribution in wood during drying using digital x-ray microscopy. Drying Technol. 26:590–595.10.1080/07373930801944796Search in Google Scholar

Wiberg, P., Moren, T.J. (1999) Moisture flux determination in wood during drying above fiber saturation point using CT-scanning and digital image processing. Holz Roh Werkst. 57:137–144.10.1007/s001070050029Search in Google Scholar

Younsi, R., Kocaefe, D., Poncsak, S., Kocaefe, Y. (2007) Computational modeling of heat and mass transfer during the high-temperature heat treatment of wood. Appl. Therm. Eng. 27:1424–1431.Search in Google Scholar

Younsi, R., Kocaefe, D., Poncsak, S., Kocaefe, Y., Gastonguay, L. (2008) CFD modeling and experimental validation of heat and mass transfer in wood poles subjected to high temperatures: a conjugate approach. Heat Mass Transfer 44:1497–1509.10.1007/s00231-008-0382-8Search in Google Scholar

Zhu, Z., Kaliske, M. (2011) Numerical simulation of coupled heat and mass transfer in wood dried at high temperature. Heat Mass Transfer 47:351–358.10.1007/s00231-010-0728-xSearch in Google Scholar

Received: 2013-3-24
Accepted: 2013-7-12
Published Online: 2013-08-10
Published in Print: 2014-02-01

©2014 by Walter de Gruyter Berlin Boston

Downloaded on 8.12.2023 from
Scroll to top button