Study On The Thermal Conductivity Properties Of Porous Materials

With the development of aerospace,electronic industry,automobile industry,energy power and other industries,greater demands are put forward for materials,such as: light weight,excellent thermal performance,good mechanical performance,shock absorption,energy absorption and other characteristics.Porous materials are widely used in construction,aerospace,microelectronics,catalytic converter,energy storage,construction and other industries due to their high porosity,low density,good permeability,large specific surface area,sound insulation,impact resistance and unique thermal conductivity.It is of great significance and practical value to study the heat transfer characteristics of porous materials in the field of its application.In this paper,the thermal conductivities of three typical porous materials are studied systematically,including skeleton porous materials,fiber porous materials and particle porous materials.Firstly,for the skeleton porous materials,an effective equivalent thermal conductivity model is established and the results are compared with the experimental results to verify the accuracy of thermal conductivity model based on the regular dodecahedron geometry and the concave triangular prismatic ligament and node,.The influences of structural parameters such as porosity,filling phase and hollowness of ligaments on the thermal conductivity are studied.Secondly,the equivalent thermal conductivity model is established for fiber porous materials.The influences of the diameter,porosity and contact thermal resistance of nanowires on the thermal conductivity are analyzed.Carbon nanofiber foams were prepared and their thermoelectric values in different directions were studied.Finally,SiC porous materials were prepared with excellent thermal insulation properties.Based on the Parsher particle packing geometry model and Johnson-Kendall-Roberts contact model,the thermal conductivity model of particle porous materials was established,and the specific reasons for the low thermal conductivity of SiC were analyzed.And through acetic acid treatment,an effective preparation method is proposed to improve the thermal conductivity and electrical conductivity of copper nanoparticles porous materials.