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Title: Measurements of moisture transport in wood-based materials under isothermal and nonisothermal conditions

Source: 30 Years of Research : Proceedings, Thermal Performance of the Exterior Envelopes of Whole Buildings X : U.S. Department of Energy, Oak Ridge National Laboratory : Buildings X Conference, Dec. 2-7, 2007. Atlanta, Ga. : American Society for Heating, Refri

Author(s)Glass, Samuel V.

Publication Year: 2007  View PDF »

Category: Journal Articles
Associated Research Project(s):   FPL-4723-1

Abstract: Building envelopes in various climates are exposed to a broad range of temperature and moisture conditions. Moisture transfer across the building envelope by diffusion in the hygroscopic range usually involves a thermal gradient as well as a water vapor pressure gradient. While many studies using common building materials have explored the dependence of water vapor permeability on relative humidity (RH), very few measurements have been made to characterize the effect of temperature under isothermal conditions or the effect of a thermal gradient. These effects may be of special importance in wood-based building materials. In our experiments, water vapor permeance is measured by sealing a material between two chambers that are independently controlled; temperature, RH, and the rate of mass transfer are measured on both sides of the specimen. Results are reported for 11-mm-thick plywood at room temperature and compared with other isothermal permeability data from the literature. Three experiments with conditions of nearly constant water vapor pressure in the presence of a thermal gradient show small moisture flows from high RH to low RH (from the cold side to the warm side) that might have been caused by water vapor pressure gradients within the experimental error. These results are discussed in the context of similar experiments in the literature.

Keywords: Plywood, water vapor pressure, mass transfer, buildings, environmental engineering, wood, moisture, water vapor transport, humidity, wooden buildings, testing, moisture, humidity, control, dampness in buildings, temperature, thermal properties, building materials, hygroscopicity, moisture content of wood in service, water vapor, moisture content, moisture control

File size: 492 kb(s)

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RITS Product ID: 1738
Current FPL Scientist associated with this product
Glass, Samuel V.
Research Physical Scientist
  

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