Radiative Properties of High and Low Density Fiberglass Insulation in the 4-38.5 km Wavelength Region

Abstract

Previously work was performed to determine radiative properties of low density fiberglass insulation in the 4-18.5 mm wavelength region; these properties were determined from directional-hemispherical reflectance data. This present work expands on the properties previously available by yielding the radiative properties of not only low density fiberglass insulation but also of high density fiberglass insulation in the extended wavelength region of 4-38.5 mm. Also these properties were determined from both directional-hemispherical and hemispherical-directional reflectance data. An inversion method was used to determine the spectral radiative properties by coupling the experimental data and theoretical reflectance values via the nonlinear least squares method for determining the radiative properties. The theoretical reflectance values were computed from the discrete ordinates solution to the radiative transport equation. These spectral radiative properties are important for conducting realistic radiative heat transfer computations associated with commonly used fiberglass insulations.