Abstract
The thermal insulation properties of bark and wood of a poplar tree (Populus nigra × alba) were investigated using a guarded hot plate device (GHP) and a purpose-built miniature heat flow meter (Mini-HFM). To reduce their density and improve their performance as insulation material, bark and wood were chemically treated. The correlation between thermal conductivity and test temperature as well as between thermal conductivity and material moisture was investigated. By means of the treatment 44 and 34% of the mass of bark and wood, respectively, was removed and the equilibrium moisture content of the both materials decreased significantly. For untreated bark, a thermal conductivity of 0.071 Wm−1 K−1 and 0.140 Wm−1 K−1, respectively, were determined in transverse and axial direction. For wood, measurements showed comparably higher conductivities of 0.078 Wm−1 K−1 and 0.204 Wm−1 K−1 in transverse and axial direction. By reducing density, thermal conductivity of bark decreased up to 24%, whereas for wood reductions between 10 and 35% were found. It was shown that the self-constructed Mini-HFM is a useful and reliable instrument to determine the thermal conductivity on a small wood sample in the three main anatomical directions.
Funding source: Austrian Research Promotion Agency – FFG
Award Identifier / Grant number: Project No.: 844.608
-
Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.
-
Research funding: The authors gratefully acknowledge the financial support from the Competence Centre for Wood Composites and Wood Chemistry, Wood K plus and for financial support of the project ‘Wood: next generation materials and processes - from fundamentals to implementations’, funded by the Austrian Research Promotion Agency – FFG (Project no.: 844.608).
-
Conflict of interest statement: The authors declare no conflicts of interest regarding this article.
References
Argun, M.E. and Dursun, S. (2008). Cadmium removal using activated pine bark. J. Int. Environ. Appl. Sci. 3: 37–42.Search in Google Scholar
Bozsaky, D. (2010). The historical development of thermal insulation materials. Period. Polytech. Arch. 41: 49–56, doi:https://doi.org/10.3311/pp.ar.2010-2.02.Search in Google Scholar
Bučar, B. and Straže, A. (2008). 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: 362.10.1515/HF.2008.021Search in Google Scholar
Busquets-Ferrer, M., Czabany, I., Vay, O., Gindl-Altmutter, W., and Hansmann, C. (2020). Alkali-extracted tree bark for efficient bio-based thermal insulation. Construct. Build. Mater. 271: 121577.10.1016/j.conbuildmat.2020.121577Search in Google Scholar
Colom, X., Carrillo, F., Nogués, F., and Garriga, P. (2003). Structural analysis of photodegraded wood by means of FTIR spectroscopy. Polym. Degrad. Stabil. 80: 543–549, https://doi.org/10.1016/s0141-3910(03)00051-x.Search in Google Scholar
Czajkowski, Ł., Olek, W., and Weres, J. (2020). Effects of heat treatment on thermal properties of European beech wood. Eur. J. Wood Wood Prod. 78: 425–431, https://doi.org/10.1007/s00107-020-01525-w.Search in Google Scholar
Czichos, H. (2000). Die Grundlagen der ingenieurwissenschaften. Werkstoffe, wärmeleitfähigkeit von Werkstoffen. Berlin/Heidelberg: Springer-Verlag.10.1007/978-3-662-06652-2Search in Google Scholar
Díaz, A.R., Flores, E.I.S., Yanez, S.J., Vasco, D.A., Pina, J.C., and Guzmán, C.F. (2019). Multiscale modeling of the thermal conductivity of wood and its application to cross-laminated timber. Int. J. Therm. Sci. 144: 79–92, https://doi.org/10.1016/j.ijthermalsci.2019.05.016.Search in Google Scholar
Eitelberger, J. and Hofstetter, K. (2011). Prediction of transport properties of wood below the fiber saturation point – a multiscale homogenization approach and its experimental validation. Part II: steady state moisture diffusion coefficient. Compos. Sci. Technol. 71: 145–151, https://doi.org/10.1016/j.compscitech.2010.11.006.Search in Google Scholar
Feng, S., Cheng, S., Yuan, Z., Leitch, M., and Xu, C. (2013). Valorization of bark for chemicals and materials: a review. Renew. Sustain. Energy Rev. 26: 560–578, https://doi.org/10.1016/j.rser.2013.06.024.Search in Google Scholar
Fengel, D. and Wegener, G. (1989). Wood – chemistry, ultrastructure, reactions. Berlin: Walter de Gruyter.Search in Google Scholar
Griffiths, E., Kaye, G.W.C., and Petavel, J.E. (1923). The measurement of thermal conductivity. Proc. R. Soc. Lond. A 104: 71–98, https://doi.org/10.1098/rspa.1923.0095.Search in Google Scholar
Jelle, B.P. (2011). Traditional, state-of-the-art and future thermal building insulation materials and solutions – properties, requirements and possibilities. Energy Build. 43: 2549–2563, https://doi.org/10.1016/j.enbuild.2011.05.015.Search in Google Scholar
Kain, G., Barbu, M.C., Hinterreiter, S., Richter, K., and Petutschnigg, A. (2013). Using bark as a heat insulation material. BioResources 8: 3718–2731, https://doi.org/10.15376/biores.8.3.3718-3731.Search in Google Scholar
Kain, G., Lienbacher, B., Barbu, M.-C., Plank, B., Richter, K., and Petutschnigg, A. (2016). Evaluation of relationships between particle orientation and thermal conductivity in bark insulation board by means of CT and discrete modeling. Case Stud. Nondestruct. Test. Evaluation 6: 21–29, doi:https://doi.org/10.1016/j.csndt.2016.03.002.Search in Google Scholar
Klügl, J. and Di Pietro, G. (2021). The interaction of water with archaeological and ethnographic birch bark and its effects on swelling, shrinkage and deformations. Heritage Sci. 9: 3, https://doi.org/10.1186/s40494-020-00476-y.Search in Google Scholar
Kühlmann, G. (1962). Untersuchung der thermischen eigenschaften von holz und spanplatten in abhängigkeit von feuchtigkeit und temperatur im hygroskopischen bereich. Holz als Roh- Werkst. 20: 259–270, https://doi.org/10.1007/bf02604682.Search in Google Scholar
Kulterer, K., Penz, M., Schuster, M., Maier, P., Bargmann, E., and Bader, H. (2017). Leitfaden technische Isolierung. Austrian Energy Agency - Bundesministerium für Land- und Forstwirtschaft, Umwelt und Wasserwirtschaft, pp. 1–80.Search in Google Scholar
Li, T., Song, J., Zhao, X., Yang, Z., Pastel, G., Xu, S., Jia, C., Dai, J., Chen, C., Gong, A., et al.. (2018). Anisotropic, lightweight, strong, and super thermally insulating nanowood with naturally aligned nanocellulose. Sci. Adv. 4: eaar3724, https://doi.org/10.1126/sciadv.aar3724.Search in Google Scholar PubMed PubMed Central
Lima, M.A., Lavorente, G.B., da Silva, H.K.P., Bragatto, J., Rezende, C.A., Bernardinelli, O.D., deAzevedo, E.R., Gomez, L.D., McQueen-Mason, S.J., Labate, C.A., et al.. (2013). Effects of pretreatment on morphology, chemical composition and enzymatic digestibility of eucalyptus bark: a potentially valuable source of fermentable sugars for biofuel production – part 1. Biotechnol. Biofuels 6: 75, https://doi.org/10.1186/1754-6834-6-75.Search in Google Scholar PubMed PubMed Central
MacLean, J.D. (1941). Thermal conductivity of wood. Heating/Piping/Air Cond. 13: 380–391.Search in Google Scholar
Martin, R.E. (1963). Thermal properties of bark. For. Prod. J. 13: 419–426.Search in Google Scholar
Martin, R.E. (1969). Characterization of southern pine barks. For. Prod. J. 19: 23–30, https://doi.org/10.2307/2987277.Search in Google Scholar
Moosavinejad, S.M., Madhoushi, M., Vakili, M., and Rasouli, D. (2019). Evaluation of degradation in chemical compounds of wood in historical buildings using FT-IR and FT-Raman vibrational spectroscopy. Maderas Cienc. Tecnol. 21: 381–392, https://doi.org/10.4067/s0718-221x2019005000310.Search in Google Scholar
Narayanamurti, D. and Ranganathan, V. (1941). The thermal conductivity of Indian timbers. Proc. Indian Acad. Sci. A 13: 300–315, https://doi.org/10.1007/bf03049008.Search in Google Scholar
Niemz, P. and Sonderegger, W.U. (2017). Holzpysik: Physik des Holzes und der Holzwerkstoffe. München: Carl Hanser Verlag.10.3139/9783446445468Search in Google Scholar
Nopens, M., Riegler, M., Hansmann, C., and Krause, A. (2019). Simultaneous change of wood mass and dimension caused by moisture dynamics. Sci. Rep. 9: 10309, https://doi.org/10.1038/s41598-019-46381-8.Search in Google Scholar PubMed PubMed Central
Palacios, A., Cong, L., Navarro, M.E., Ding, Y., and Barreneche, C. (2019). Thermal conductivity measurement techniques for characterizing thermal energy storage materials – a review. Renew. Sustain. Energy Rev. 108: 32–52, https://doi.org/10.1016/j.rser.2019.03.020.Search in Google Scholar
Pandey, K.K. and Theagarajan, K.S. (1997). Analysis of wood surfaces and ground wood by diffuse reflectance (DRIFT) and photoacoustic (PAS) Fourier transform infrared spectroscopic techniques. Holz als Roh- Werkst. 55: 383–390, https://doi.org/10.1007/s001070050251.Search in Google Scholar
Pásztory, Z. and Ronyecz, I. (2013). The thermal insulation capacity of tree bark. Acta Silv. Ling. Hung. 9: 111–117, https://doi.org/10.2478/aslh-2013-0009.Search in Google Scholar
Qin, Y., Peng, Q., Zhu, Y., Zhao, X., Lin, Z., He, X., and Li, Y. (2019). Lightweight, mechanically flexible and thermally superinsulating rGO/polyimide nanocomposite foam with an anisotropic microstructure. Nanoscale Adv. 1: 4895–4903, https://doi.org/10.1039/c9na00444k.Search in Google Scholar
Ratcliffe, E.H. (1964a). A review of thermal conductivity data. Part 1. Wood 29: 49–51.Search in Google Scholar
Ratcliffe, E.H. (1964b). A review of thermal conductivity data. Part 2. Wood 29: 46–49.Search in Google Scholar
Rijsdijk, J.F. and Laming, P.B. (1994). Physical and related properties of 145 timbers, Information for practice. Dordrecht: Springer Science, Business Media.10.1007/978-94-015-8364-0Search in Google Scholar
Rowley, F.B. (1933). The heat conductivity of wood at climatic temperature differences. Heating/Piping/Air Cond. 5: 3–323.Search in Google Scholar
Schneider, A. and Engelhardt, F. (1977). Vergleichende untersuchungen über die wärmeleitfähigkeit von holzspan- und rindenplatten. Holz als Roh- Werkst. 35: 273–278, https://doi.org/10.1007/bf02619357.Search in Google Scholar
Sonderegger, W., Hering, S., and Niemz, P. (2011). Thermal behaviour of Norway spruce and European beech in and between the principal anatomical directions. Holzforschung 65: 369–375, https://doi.org/10.1515/hf.2011.036.Search in Google Scholar
Standard International (1975). Wood – determination of moisture content for physical and mechanical tests (ISO 3130-1975).Search in Google Scholar
Steinhagen, H.P. (1977). Thermal conductive properties of wood, green and dry, from −40 °C to +100 °C: a literature review. General Technical Report FPL-9. Madison, Wisconsin: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory.Search in Google Scholar
Trockenbrodt, M. (1991). Qualitative structural changes during bark development in Quercus robur, Ulmus glabra, Populus tremula and Betula pendula. IAWA J. 12: 5–22, https://doi.org/10.1163/22941932-90001199.Search in Google Scholar
Vaucher, H. (1997). Baumrinden: aussehen, struktur, funktion, eigenschaften. Augsburg: Naturbuch Verlag.Search in Google Scholar
Vay, O., Obersriebnig, M., Müller, U., Konnerth, J., and Gindl-Altmutter, W. (2013). Studying thermal conductivity of wood at cell wall level by scanning thermal microscopy (SThM). Holzforschung 67: 155–159, https://doi.org/10.1515/hf-2012-0052.Search in Google Scholar
Vay, O., De Borst, K., Hansmann, C., Teischinger, A., and Müller, U. (2015). Thermal conductivity of wood at angles to the principal anatomical directions. Wood Sci. Technol. 49: 577–589, https://doi.org/10.1007/s00226-015-0716-x.Search in Google Scholar
Wangaard, F.F. (1940). Transverse heat conductivity of wood. Heating/Piping/Air Cond. 12: 459–464, https://doi.org/10.1093/oxfordjournals.jhered.a104813.Search in Google Scholar
Xing, C., Deng, J., Zhang, S.Y., Riedl, B., and Cloutier, A. (2006). Impact of bark content on the properties of medium density fiberboard (MDF) in four species grown in eastern Canada. For. Prod. J. 56: 64–69.Search in Google Scholar
© 2021 Walter de Gruyter GmbH, Berlin/Boston
