A model for predicting thermal conductivity of porous composite materials

Advancements in Thermal Insulation through Ceramic Micro-Nanofiber Materials

“…The structure of fibrous materials is complex, and they are commonly thought of as simplified semi-transparent media consisting of elongated, slender fibers, typically a few micrometers in diameter, interspersed with air or other gases that fill the interstitial space between the fibers. To facilitate the study of the thermal conductivity of fiber insulation materials, several basic theoretical thermal conductivity models due to solid and gas conductions for fibrous media have been developed, such as the Parallel model [43,[47][48][49][50][51][52], Series model [47,[53][54][55], Singh model [56,57], Bankvall model [54,[58][59][60], Maxwell-Eucken model [55], Effective medium theory (EMT) model [51,61,62], Hamilton model [53,61,63], and Bhattacharyya model [43,64,65].…”

“…Moreover, Bankvall et al [58] postulated that the conduction of solids and gases is both parallel and series, where α is the ratio of parallel heat conduction. The Maxwell model assumes that the filler is randomly dispersed in the matrix, and then calculates the thermal conductivity of the composite without considering the interaction of the dispersed particles in the matrix [55]. The EMT model assumes that the two-phase components can be distributed continuously or discontinuously in the composite, which can be transmitted independently or dispersed in a material [51,61].…”

“…[54,58-60] [47,[53][54][55] where λ c is thermal conductivity due to solid and gas conductions, λ g is the gas thermal conductivity, λ s is the solid thermal conductivity, and ω is the volume fraction of solid.…”