Reduction of radiative heat transfer in thermal insulations by use of dielectric coated fibers

This paper reports an analysis on using coated silica fibers to reduce radiative heat transfer through thermal insulations. Considerations were given to silica fibers of diameters 2, 5, and 10 μm. They were coated with either a 0.2 μm silicon coating or a 0.2 μm silicon inner coating and a 0.1 μm silica outer coating. Calculations were performed to determine the ratio of radiative heat flux for coated fibers to that for uncoated fibers. The calculations were made for both constant fiber number density and constant bulk density. It was found that keeping the fiber number density constant resulted in larger reductions in radiative heat flow. For the test conditions examined, reduction as high as 75 percent was shown to be possible.