Apparent Thermal Conductivity of High Density and Low Density Fiberglass Insulations

Abstract

A numerical model for coupled conduction and radiation heat transfer in fibrous insulations was used to predict the steady-state heat transfer in two standard reference materials (SRM); SRM 1451 (low density fiberglass - 9.25 kg/m3) and SRM 1450(b)(high density fiberglass - 129 kg/m3). Gray isotropic radiative properties were input into the transient numerical model which marches to steady state. Theoretical apparent thermal conductivity values were computed as a function of mean temperature for both density fiberglasses and as a function of thickness and density for the low density fiberglass insulation. These results are compared to the experimental apparent thermal conductivity values obtained from tests performed at the Oak Ridge National Laboratory (ORNL). In addition, the relative importance of radiation and conduction for different density fiberglass insulations is also discussed.