Effect of temperature on unsteady-state moisture diffusion through wood.

摘要

The effect of drying temperature on unsteady-state moisture diffusion behavior was studied by drying 5.5-inch long, 4-inch wide and 1-inch thick specimens of yellow poplar (Liriodendron tulipifera L.), red oak (Quercus spp.) and white oak (Quercus alba L.). Drying rate versus average moisture content data were obtained at four temperature levels (90, 110, 130 and 150{dollar}spcirc{dollar}F) and two equilibrium moisture content levels (10 and 5%) in a controlled temperature and humidity chamber.; For each specimen at each temperature, two estimates of the diffusion coefficient were made, one for the first half of drying and the other for the second half of drying. These two estimates were used separately across the four temperatures to obtain estimates of the activation energy for moisture diffusion through wood.; That the moisture diffusion through wood is an activated process was indicated by the fact that the plots of the logarithm of diffusion coefficient versus the reciprocal of absolute temperature were linear. However, the calculated activation energies were low and were also related to the specific gravity of the wood. The calculated activation energies were 4184 cal/mole for yellow popular, 6340 cal/mole for red oak and 10695 cal/mole for white oak.