Molecular Dynamics Study on the Thermal Conductivity of Mesoporous Silica
Mesoporous silica is a synthetic nanoporous material,and its thermal properties regula-tion is essential for the promotion of nanomaterials.In this paper,a double-scale channel distribution model is developed based on the typical mesoporous silica SBA-15.And the inverse non-equilibrium molecular dynamics method is adopted to study the heat carrier transport and heat transfer behav-ior inside the mesoporous silica.The results show that the thermal conductivity of amorphous and mesoporous silica is insensitive to size effects when the system length is greater than 12.84 nm.The mechanisms for tuning the heat transfer characteristics mainly depend on pore size and porosity.And reducing the pore size can further enhance the thermal insulation performance of the material at the same porosity.The microchannels between mesopores disrupt the continuity of heat carrier propagation and expand the specific surface area of the material,resulting in enhanced heat car-rier interfacial scattering and thermal resistance.Moreover,the analysis of vibrational density of states(VDOS)demonstrates that mesopores and microchannels hinder nanoscale heat transfer.The porous structure reduces the average frequency of the heat carrier and leads to a decrease in thermal conductivity.
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