Simsor: A Computer Simulation of Water Sorption in Wood


  • C. Arthur Hart


Computer simulation, drying simulation, kiln drying simulation, moisture movement, sorption


SIMSOR, a computerized simulation of sorption, represents an effort to structure the known essential physical phenomena that control the drying behavior of wood in such a way as to permit the duplication, with acceptable accuracy and cost, of experimental data obtained from actual drying studies. Programming knowledge is not required for its use. It can accurately simulate a typical red oak kiln schedule in less than one minute of computer time. It will handle adsorption or desorption, from freezing temperatures to boiling temperatures, and at humidities from virtually 100% to nearly 0%. Wood of any thickness and density, permeable or impermeable, can be simulated over any desired range of wood moisture content. However, its use to duplicate experimental data requires that the diffusion coefficient be adequately defined over the entire applicable range of moisture contents. At present, this will generally require a trial and-error approach, especially in the free water range. Free water is treated the same as bound water, but the temperature dependence may be canceled, if desired.

Although the simulation has already been proven under a variety of trials, it still needs to be tested under the widest possible range of applications. Wherever duplication of experimental data proves the validity of the simulation, it can then be used to provide a much more comprehensive analysis of wood-drying procedures and variables, and in far less time at far less cost, than is possible by actual physical trials.


Ashworth, J. C. 1978. Design of drying schedules in kiln drying of softwood timber. Presented at First International Drying Symposium, Montreal, August 1978. To be published in Developments in drying, Hemisphere Press, Princeton, NJ.nBindon, H. H. 1963. A critical review of tables and charts used in psychrometry. Chapter 1, pages 3-15 in Arnold Wexler, ed., Humidity and moisture. Reinhold Pub. Corp., New York, NY.nBramhall, G. 1979. Mathematical model for lumber drying. I. Principles involved. Wood Sci. 12(1):14-21.nForest Products Laboratory. 1974. Wood handbook. USDA Agric. Handb. 72.nHart, C. A. 1977. Effective surface moisture content of wood during sorption. Wood Sci. 9(4):194-201.nHart, C. A., and W. M. Darwin, Jr. 1971. The slow drying rate of white oak. Wood Sci. 4(1):46-54.nKawai, S., K. Nakato, and T. Sadoh. 1978. Prediction of moisture distribution in wood drying. Mokuzai Gakkaishi 24(8):520-525.nMcNamara, W. S. 1969. Effects of stress on the diffusion of moisture in wood. Ph.D. thesis, Dep. of Wood and Paper Sci., North Carolina State University at Raleigh. University Microfilm, Ann Arbor, MI.nMoschler, W. W., Jr., and R. E. Martin. 1968. Diffusion equation solutions in experimental wood drying. Wood Sci. 1(1):47-57.nPeck, R. E., and J. Y. Kauh. 1968. Evaluation of drying schedules. AIChE 15(1):85-88.nRasmussen, E. F. 1961. Dry kiln operator's manual. USDA Agric. Handb. 188, 197 pp.nSchultz, T. P. 1978. An air drying technique to control surface checking in refractory hardwoods. Master of Science thesis, Dep. of Wood and Paper Sci., North Carolina State University at Raleigh.nSiau, J. F. 1971. Flow in wood. Syracuse University Press, Syracuse, NY.nSmith, H. H. 1963. Relative humidity and equilibrium moisture content graphs and tables for use in kiln-drying lumber. Forest Prod. Lab. Rep. No. 1651, Madison, WI.nStamm, A. J. 1964. Wood and cellulose science. Ronald Press, New York, NY.nStevens, W. C. et al. 1956. An investigation into the effects of air speed on the transference of heat from air to water. Timber Technol. 64(2208):537-539.nWeast, R. C. 1973. Handbook of chemistry and physics, 54th ed. The Chemical Rubber Publishing Company, Cleveland, OH.n






Research Contributions