Drying Douglas-fir Lumber: a Computer Simulation
Keywords:Drying, computer simulation, moisture measurement, Douglas-fir lumber
Three experimental kiln runs were designed to investigate how well the drying rate of 2-inch-thick lumber from Douglas-fir heartwood can be simulated by Hart's computer model. Simulated data were compared with gravimetric records and with electrical measurements obtained using the moisture-monitoring system designed by Forrer. This thermomoisture meter proved useful in continuously measuring moisture gradients and temperatures in boards. The first step of the computer simulation showed how diffusion coefficients varied with moisture content; however, two adjustments of the computer inputs were needed to arrive at good agreement between simulated and observed drying rates.
It was concluded that Hart's computer simulation programs and Forrer's thermomoisture meter are excellent tools for future lumber drying research and improvement of kiln schedules.
Bramhall, G. 1979a. Mathematical model for lumber drying. I. Principles involved. Wood Sci. 12(1):14-21.nBramhall, G. 1979b. Mathematical model for lumber drying. II. The model. Wood Sci. 12(1):22-31.nBrown, H. P., A. J. Panshin, and C. C. Forsaith. 1952. Textbook of wood technology. Vol. 2. P. 159. McGraw-Hill, New York. 783 pp.nClark, J. D., and J. W. Williams 1933. The electrical conductivity of commercial dielectrics and its variation with temperature. J. Phys. Chem. 17(1):119-131.nClaxton, H. D. 1966. Computer simulation of kiln drying. Western Dry Kiln Clubs Proc. 18:55-61.nDavidson, R. W. 1958. The effect of temperature on the electrical resistance of wood. For. Prod. J. 8:160-164.nForrer, J. 1984. An electronic system for monitoring gradients of drying wood. For. Prod. J. 34(778):34-38.nHart, C. A. 1965. The drying of wood. Ext. Cir. 471, The North Carolina Agricultural Extension Service, Raleigh.nHart, C. A. 1977. Effective surface moisture content of wood during sorption. Wood Sci. 9(4):194-210.nHart, C. A. 1981. SIMSOR: A computer simulation of water in wood. Wood Fiber 13(1):46-71.nHart, C. A. 1983. A user's manual for a family of simulations of moisture sorption in wood. Dept. of Wood and Paper Science, North Carolina State University, Raleigh.nJames, W. L. 1963. Electric moisture meters for wood. USDA For. Serv. Res. Note FPL-08. For. Prod. Lab., Madison, WI.nKawai, S., K. Makato, and T. Sadoh. 1978. Prediction of moisture distribution in wood during drying. Mokuzai Gakkaishi 24(8):120-125.nKeylwerth, R., and D. Noack. 1956. [The influence of higher temperatures when electrically measuring wood moisture content using the resistance method.] Holz als Roh u. Werkst. 14(5): 162-172.nLin, R. T. 1965. A study of the electrical conduction in wood. For. Prod. J. 15(11):506-514.nMcNamara, W. S., and C. A. Hart. 1971. An analysis of interval and average diffusion coefficients for unsteady-state movement of moisture in wood. Wood Sci. 4(1):37-45.nMoschler, W. W., Jr., and R. E. Martin. 1968. Diffusion equation solution in experimental wood drying. Wood Sci. 1(1):47-57.nRasmussen, E. F. 1961. Dry kiln operator's manual. USDA For. Serv. Agric. Handbook No. 188. For. Prod. Lab., Madison, WI.nSiau, J. F. 1984. Transport processes in wood. Pp. 151-171. Springer, New York. 245 pp.nSkaar, C. 1948. The dielectric properties of wood at several radio frequencies. Tech. Publ. 691. New York State College, Forestry, Syracuse.nSkaar, C. 1964. Some factors involved in the electrical determination of moisture gradients in wood. For. Prod. J. 14(6):239-243.nStamm, A. J. 1927. The electrical resistance of wood as a measure of its moisture content. Ind. Eng. Chem. 19(9):1021-1025.n
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.