MADERAS: Ciencia y Tecnología

  Previous Article | Back to Volume | Next Article
  Abstract | References | Citation | Download | Preview | Statistics
Sample volume 1
Title Inclusion of the sorption hysteresis phenomenon in future drying models: Some basic considerations
Author Jarl-Gunnar Salin
Abstract The sorption hysteresis effect, i.e. different wood equilibrium moisture contents (EMCs) in desorption and adsorption for the same relative humidity, is well known. However, quantitative sorption isotherms, in the form of tables or analytical correlations, are almost always given as the average of the desorption and adsorption curves. Consequently most drying simulation models use these average curves, and does not take into account the sorption hysteresis phenomenon. The equilibrium state of a wood sample is thus not a function of the relative humidity only, but depends on the moisture history also. This means that Fick's equations - with moisture content as a single driving force - are not valid any more. For a pure desorption process the state of the sample follows the desorption isotherm, but a problem arises when desorption is followed by adsorption - as for instance in the timber conditioning phase. It seems reasonable to assume that for each EMC point, on or between the desorption/adsorption isotherms, the moisture content change follows a unique path when the surrounding climate changes. This path - the so called scanning curve - does not need to be the same in desorption and adsorption. Some selected results and corresponding scanning curve suggestions are presented and discussed. Drying models with the sorption hysteresis phenomenon included should be developed for the analysis of experimental data and more generally for use as an improved tool in practical applications.
Anon. 1999. Wood handbook. Wood as an engineering material (Gen. Tech. Rep. 113), USDA Forest Service.
Babiak, M. 2007. Sorption isotherms of wood. In P. Perré (Ed.), Fundamentals of wood drying, A.R.BO.LOR, Nancy, France, ISBN 9 782907 086127. 
Bramhall, G. 1979. Mathematical model for lumber drying. I. Principles involved. Wood Sci. 12: 15-21.
Cloutier, A.; Fortin, Y. 1994. Wood drying modelling based on the water potential concept: Hysteresis effects. Drying Technology  12(8): 1793-1814
Frandsen, H.L. 2007. Selected constitutive models for simulating the hygro-mechanical response of wood. PhD thesis, Aalborg University, Aalborg, Denmark.
Constitutive_Models_for_Simulating_the_Hygromechanical_Response_of_Wood.  (consulted January 28, 2011)
Frandsen, H.L.; Damkilde, L. 2000. A sorption hysteresis model for cellulosic materials. Proceedings of the 19th Nordic Seminar on Computational Mechanics, Lund, Sweden, 77-80p.
Frandsen, H.L.; Svensson, S. 2007. Implementation of sorption hysteresis in multi-Fickian moisture transport.  Holzforschung  61(6): 693-701.
Gjerdrum, P. 2008. Modeling moisture sorption and its dynamics in commercial, kiln-dried softwood boards. Drying Technology  26(9): 1140-1144.
Hartley, I.D.; Avramidis, S. 2002. Sorption hysteresis of Western Canadian softwood species. 
Journal of the Institute of Wood Science 16(1): 63-64.
Hukka, A. 1999. The effective diffusion coefficient and mass transfer coefficient of Nordic softwoods 
as calculated from direct drying experiments. Holzforschung 53: 534-540.
Hukka, A.;  Oksanen, O. 1999. Convective mass transfer coefficient at wooden surface in jet drying 
of veneer. Holzforschung 53: 204-208.
Ilic, M.; Turner, I.W. 1991. A continuum model of drying processes involving a jump through hysteresis. Drying Technology 9(1): 79-111.
Kawai, S., Nakato.; Sadoh, T. 1978. Prediction of moisture distribution in wood during drying. 
Mokuzai Gakkaishi 24(8): 520-525.
Krupinska, B.; Strømmen, I.; Pakowski, Z.; Eikevik, T.M. 2007. Modelling of sorption isotherms of various kinds of wood at different temperature conditions. Drying Technology 25(9): 1463-1470.
Morén, T.; Salin, JG.; Söderström, O. 1992. Determination of the surface emission factors in wood sorption experiments. 3rd IUFRO International Conference on Wood Drying, Vienna, Austria, Aug. 18-21p.
Peralta, P.N. 1995. Modelling wood moisture sorption hysteresis using the independent-domain theory. Wood and Fiber Science 27: 250-257.
Salin, JG. 1996. Mass transfer from wooden surfaces. Proceedings of 10th International Drying Symposium, Kraków, Poland, July 30 – Aug. 2, Vol A, 711-718p.
Salin, JG. 2007. External heat and mass transfer. In: Perré, P. (Ed.) Fundamentals of wood drying. A.R.BO.LOR Nancy, France. ISBN 9 782907 086127.
Shmulsky, R.; Kadir, K.; Erickson, R. 2001. Effect of sample geometry on EMC and moisture hysteresis of red oak. Wood and Fiber Science 33: 662-666.
Shmulsky, R.; Kadir, K.; Erickson, R. 2002. Effect of air velocity on surface EMC in the drying of red oak lumber.  Forest Prod. J. 52(1): 78-80.
Stamm, A.J. 1971. Review of nine methods for determining fiber saturation points of wood and wood products.  Wood Science 4(2): 114-128
Stanish, M.A. 1986. The roles of bound water chemical potential and gas phase diffusion in moisture transport through wood. Wood Sci. Techn. 19: 53-70.
Time, B. 1998. Hygroscopic moisture transport in wood. PhD thesis, Norwegian University of Science and Technology, Trondheim, Norway. (consulted January 28, 2011). 
Time, B. 2002. Studies on hygroscopic moisture transport in Norway spruce (Picea abies). Part 2: Modelling of transient moisture transport and hysteresis in wood.  Holz als Roh- und Werkstoff  60(6): 405-410.
Vidal, M.; Cloutier, A. 2006. Evaluation of wood sorption models for high temperatures. Maderas. 
Ciencia y tecnología 7(3):145-158.
Keywords Modelling; sorption hysteresis; wood drying
Download Full PDF Download
  Previous Article | Back to Volume | Next Article
Search in articles
Journal Published articles
Journal Hits
MCYT 93629
Journal Downloads
MCYT 260
Total users online -