Porous materials with thin interlayers for optimal thermal insulation

The combined radiative and conductive heat transfer through highly porous materials is a typical nonlinear problem in engineering thermal insulations. The complexity of the integral radiative and conductive heat transfer equations especially the nonlinearity of the heat radiation item makes it extremely difficult to obtain exact solution. A theoretical model was developed based on the combined radiative and conductive heat transfer through the highly porous materials with thin interlayers and numerically solved by using finite volume method. The effects of interlayer parameters on the total resistance of the constructions were evaluated with a view of optimal thermal insulation ability. The results indicate that the thermal resistance of the porous materials could be effectively improved by adding appropriate number of interlayers having appropriate thickness. The possibility of the micro- or nano-porous interlayers with super-light weight, super-resistance to heat radiation, and super-permeability to water vapor was also directed in highly porous materials for optimal thermal insulation in further work.