Dr Reinhard Conradt
article posted 22 Jul 2016
Dr Manoj Choudhary
President, International Commission on Glass
Heat Transfer Phenomena in Fibrous Insulation
President, International Commisison on Glass
The paper reviews the basic mechanisms of heat transfer, namely conduction, free convection, and radiation in fibrous insulations. The relative contributions of these phenomena
to the effective or the overall thermal conductivity of fiberglass insulation are assessed. The Rayleigh number calculations show that free convection effects may generally be
ignored especially for horizontal layers. Statistical bounds for the combined fiber and gaseous thermal conduction are discussed for different orientations of the fibers.
The procedure for calculation the radiation conductivity through a solution of Maxwell’s equations is discussed and illustrative results are presented. Calculated results
for the effective conductivity for commonly used density and temperature ranges are discussed.