Examples of Nonisothermal Moisture Movement in Wood
Keywords:
Nonisothermal moisture movement, moisture profileAbstract
Moisture content gradients in wood samples subjected to nonisothermal conditions were monitored over time in two separate experiments using sample material from 1) green ash and 2) southern yellow pine. The warm and cold environment temperatures were maintained at 80 F and -40 F for both experiments. The warm environment relative humidity was maintained at 40% during the ash experiment, and 70% during the southern yellow pine experiment. The cold environment relative humidity was not controlled, but was presumed to be nearly 100%. The temperature gradient through the samples was measured using embedded Type-T thermocouples, and the moisture content profile from the warm to cold surface was determined by sectioning sample material.
Total average moisture content generally increased as a function of time, indicating that moisture flux into the sample through the warm surface was greater than flux out of the sample at the cold surface. Moisture accumulated toward the warm surface for the southern yellow pine, but was generally more evenly distributed through the depth for the ash samples. These differences were attributed to different warm environment relative humidity conditions maintained between the two experiments.
References
Anonymous. 1981. ASHRAE handbook, 1981 fundamentals. American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. Atlanta, GA. Pp. 97-108.nAvramidis, S., and J. F. Siau. 1987. Experiments in nonisothermal diffusion of moisture in wood, Part 3. Wood Sci. Technol. 21(4):329-334.nAvramidis, S., N. Kuroda, and J. F. Siau 1987. Experiments in nonisothermal diffusion of moisture in wood, Part II. Wood Fiber Sci. 19(4):407-413.nBramhall, G. 1978. Sorption diffusion in the drying of solids. Fiber Sci. Technol. 11:291-303.nChoong, E. T. 1963. Movement of moisture through a softwood in the hygroscopic range. Forest Prod. J. 13(11):489-498.nErickson, R. W., R. T. Seavey, and S. L. Quarles. 1981. Moisture adsorption and transport by wood due to a thermal gradient caused by air-to-air thermal differences. Wood Fiber 13(4):237-245.nNelson, R. M., Jr. 1986. Diffusion of bound water in wood, Part 3: A model for nonisothermal diffusion. Wood Sci. Technol. 20(4):309-328.nQuarles, S. L. 1985. Mechanisms involved in the ceiling-floor partition separation phenomenon. Ph.D. Thesis, University of Minnesota, St. Paul, MN.nSiau, J. F. 1980. Nonisothermal moisture movement in wood. Wood Science 13(1):11-13.nSiau, J. F. 1983. Chemical potential as a driving force for nonisothermal moisture movement in wood. Wood Sci. Technol. 17(2): 101-105.nSiau, J. F., and M. Babiak. 1983. Experiments on nonisothermal moisture movement in wood. Wood Fiber Sci. 15(1):40-46.nSiau, J. F., and Z. Jin. 1985. Nonisothermal moisture diffusion experiments analyzed by four alternative equations. Wood Sci Technol. 19(2):151-157.nSiau, J. F., F. Bao, and S. Avramidis. 1986. Experiments in nonisothermal diffusion of moisture in wood. Wood Fiber Sci. 18(1):84-89.nSimpson, W. T. 1971. Equilibrium moisture content prediction for wood. Forest Prod. J. 21(5): 48-49.nSkaar, C., and J. F. Siau. 1981. Thermal diffusion of bound water in wood. Wood Sci. Technol. 15(2):105-112.nStanish, M. A. 1986. The roles of bound water chemical potential and gas phase diffusion in moisture transport through wood. Wood Sci. Technol. 20(1):53-70.nTaylor, S. A., and J. W. Gary. 1961. Analysis of the simultaneous flow of water and heat or electricity with the thermodynamics of irreversible processes. Pages 80-90 in 7th International Congress of Soil Science Trans., vol. 1. Madison, WI, Elsevier Publ. Co., Amsterdam.nTuomi, R. L., and D. M. Temple. 1975. Bowing of roof joists induced by moisture gradients and slope of grain. USDA Forest Service, Forest Products Laboratory, Research Paper FPL 262. Madison, WI. 12 pp.nVoigt, H., O. Krischer, and H. Schauss. 1940. Die Feuchtigkeitsbewegung bei der Verdunstung- strocknung von Holz. Holz Roh-Werkstoff 3(10):305-321.nWengert, E. M. 1975. Prediction of moisture content in wood. Ph.D. thesis, University of Wisconsin, Madison, WI.n
Downloads
Published
Issue
Section
License
The copyright of an article published in Wood and Fiber Science is transferred to the Society of Wood Science and Technology (for U. S. Government employees: to the extent transferable), effective if and when the article is accepted for publication. This transfer grants the Society of Wood Science and Technology permission to republish all or any part of the article in any form, e.g., reprints for sale, microfiche, proceedings, etc. However, the authors reserve the following as set forth in the Copyright Law:
1. All proprietary rights other than copyright, such as patent rights.
2. The right to grant or refuse permission to third parties to republish all or part of the article or translations thereof. In the case of whole articles, such third parties must obtain Society of Wood Science and Technology written permission as well. However, the Society may grant rights with respect to Journal issues as a whole.
3. The right to use all or part of this article in future works of their own, such as lectures, press releases, reviews, text books, or reprint books.
