The Influence of Wood Specimen Geometry on Moisture Movement During Drying
Keywords:Wood drying, diffusion, modeling
AbstractThe influence of the geometrical shape of a wood specimen on the dynamics of drying under isothermal conditions is investigated in this research. Polynomials describing the dependence of half-drying time on the ratio of the area to the perimeter of the transverse section of extremely long specimens of northern red oak Quercus rubra, are presented for drying from above the fiber saturation point. This paper describes the conditions of usage of a two-dimensional moisture transfer model in contrast to the one-dimensional model for accurate prediction of the drying process. The dependence of halfdrying time on the ratio of the volume to the surface of the specimens in the shape of a rectangular parallelepiped has been investigated using a three-dimensional moisture movement model. Polynomials describing that dependence are presented.
Choong, E. T., and C. Skaar. 1969. Separating internal and external resistance of moisture in wood drying. Wood Science1(4):200-202.nFerguson, W. J., and I. W. Turner. 1995. A comparison of the finite element and control volume numerical solution techniques applied to timber drying problems below the boiling point. Int. J. Num. Methods Eng.38(3): 451-467.nFerguson, W. J., and I. W. Turner. 1996. A control volume finite element numerical simulation of the drying of spruce. J. Comput. Phys.125:59-70.nHunter, A. J. 1995. Equilibrium moisture content and the movement of water through wood above fibre saturation, Wood Sci. Technol.29:129-135.nLiu, H. 1998. Development of a simulation model for drying deformation in radiata pine boards. Ph.D. thesis, Lincoln University. New Zealand.nLiu, J. Y., and W. T. Simpson. 1997. Solutions of diffusion equation with constant diffusion and surface emission coefficients. Drying Technol.15(10):2459-2477.nNewman, A. B. 1931. The drying of porous solids: Diffusion and surface emission equations. Trans. Amer. Chem. Eng.27:203-220.nRosen, H. N. 1978. The influence of external resistance on moisture adsorption rates in wood. Wood Fiber Sci.10(3):218-228.nRosen, H. N. 1987. Recent advances in the drying of solid wood. Adv. in drying (Ed. Mujumdar). Hemisphere4: 99-146.nSamarskii, A. 1983. Difference scheme theory [in Russian]. Nauka, Moskow. 610 pp.nSiau, J. F. 1984. Transport processes in wood. Springer-Verlag, New York, NY. 245 pp.nSimpson, W. T. 1993. Determination and use of moisture diffusion coefficient to characterize drying of northern red oak (Quercus rubra). Wood Sci. Technol.27:409-420.nSimpson, W. T., and J. Y. Liu. 1997. An optimization technique to determine red oak surface and internal moisture transfer coefficients during drying. Wood Fiber Sci.29(4):312-318.nSöderström, O., and J. G. Salin. 1993. On determination of surface emission factors in wood drying. Holzfor-schung47(5):391-397.nYokota T. 1959. Diffusion of sorption-water through the cell wall of wood. Mokuzai Gakkaishi5(4):143-149.n
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