Thermal Conductivity of Wood Fiber

Abstract

The moisture can affect the thermal performance of insulation material. On hydroscopic material, the effect can reach several percent of the thermal conductivity in dry condition [1]. This paper investigates the effect of moisture on the thermal properties of wood fiber by the means of the guarded hot plate method according to 8302 ISO standard. The study involved several wood fiber materials with nominal densities between 60 and 190 kg/m3 at different state of moisture. The study was performed at a mean temperature of 283.15 K with several temperature gradients, conditioning, and test duration. The water migration inside the specimen toward the cold plate of the guarded hot plate was evaluated and put in relation with the thermal conductivity results. This paper showed the effect of moisture content on the apparent thermal conductivity. A method was proposed to avoid moisture migration in the insulation product during the measurement by putting a polyethylene film between layers of sliced materials. This method increases the accuracy and the repeatability and then gives more trustable thermal conductivity values.