Effects of three-dimensional pore structure on effective thermal conductivities of thermal insulation materials

Pore three-dimensional structure and overlap are the key factors in decreasing effective thermal conductivities of the porous insulation material. However, this coupled effect of pore structure and overlap has not been intensively studied. In this work, many three-dimensional models are built to solve the coupled heat transfer in porous insulation materials. The effects of pore structure and overlap are investigated. The results indicate that the effective contact area between pore gas and solid matrix is a key factor for the thermal insulation performance of porous insulation materials. The effect mechanism of the pore overlap on the thermal insulation is affected by the pore shape. The effect of pore overlap on the heat transfer performance is determined by the overlapping direction. The decrease of pore content is also affected by the pore shape. Overall, the pore overlap reduces the thermal insulation performance of porous insulation materials, regardless of pore shape and content change. Cylindrical (sic) pore has the largest thermal insulation performance in our cases. A quantitative correlation is built to predict the effective thermal conductivity of the porous insulation material with different pore shapes. This correlation is not only simple but also accurate.