Experiments in Nonisothermal Diffusion of Moisture in Wood. Part II.
Keywords:
Diffusion, moisture content, flux direction, relative humidityAbstract
This paper is the second in a series of papers reporting on experiments in nonisothermal diffusion of moisture in wood. Additional experimental steps to those series previously reported and one more series are included here. A reversal of flux direction was observed in all three series of experiments as the relative humidity of the warm side was increased.
The results were analyzed using the general sorption data presented in the USDA Wood Handbook using two equations. The first of each is based on a gradient of activated moisture content, and the second is based on a gradient of chemical potential which contains an additional term to account for the effect of the temperature gradient. Both equations predicted reversal of flux direction, but the second equation (chemical potential) generally provided the best fit to the experimental results.
References
Choong, E. T. 1963. Movement of moisture through a softwood in the hygroscopic range. Forest Prod. J. 13(11):489-498.nSiau, J. F., and M. Babiak. 1983. Experiments on nonisothermal moisture movement in wood. Wood Fiber 15(1):40-46.nSiau, J. F., and Z. Jin. 1985. Nonisothermal moisture diffusion experiments analyzed by four alternative equations. Wood Sci. Technol. 19:151-157.nSiau, J. F., F. Bao, and S. Avramidis. 1985. Experiments in nonisothermal diffusion of moisture in wood. Wood Fiber Sci. 16(1):84-89.nStamm, A. J. 1959. Bound-water diffusion into wood in the fiber direction. Forest Prod. J. 9(1):27-31.nU.S. Dept. of Agriculture. 1955. Wood Handbook. U.S.D.A. Handbook No. 72, U.S. Government Printing Office.n
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