Thermal conductivity modeling of hollow fiber-based porous structures for thermal insulation applications

Abstract

Hollow fiber-based porous structures (HFPSs) demonstrate promising potentials in thermal insulations. However, the thermal transport in HFPSs was not explored yet. Herein, we developed a unit cell model to explore the effect of both geometric and thermophysical parameters on the effective thermal conductivity of HFPSs. The predictions from the developed model agree with the experimental data in the literature. The modeling results show that decreasing external hollow fiber diameter, shell thickness, the thermal conductivity of solid backbone, and gas pressure can reduce the effective thermal conductivity of the HFPSs. The effective thermal conductivity of the HFPSs trends to that of stationary air (0.026 W/(m⋅K), 300 K, 1.0 atm) as porosity increases. Reducing the pore size to nanometer-scale or decreasing the gas pressure is the most effective way to achieve a thermal conductivity below that of stationary air. This work guides the structural design and optimization of HFPSs as lightweight super-thermal insulating materials.