2019 Volume 33 Issue 4 Pages 159-166
The thermal conduction of homogeneous and dense semitransparent materials like glasses consists of conductive and radiative heat transfer. The apparent thermal conductivity in steady state of semitransparent material where conductive and radiative heat transfer coexist is necessary. After deriving a temperature equation at infinity in Laplace space when steady heating one end of a 3-layer material with semitransparent material sandwiched by opaque layer, the steady-state temperature distribution equation was derived and the optical thickness and temperature dependence of the temperature distribution was investigated. Apparent steady-state thermal conductivity for entire optical thickness was derived from the temperature distribution of semitransparent material. The approximate thermal conductivity equations for large and small optical thickness were derived. The apparent thermal conductivity approximation for large optical thickness showed the same trend as the apparent thermal conductivity by Rosseland.
