The molecular dynamics(MD)simulations were used to understand the heat transfer process between the gas phase and the solid skeleton in the nanoporous silica aerogels.The amorphous silica nanoparticles were generated by the MD simulations and the energy accommodation coefficient(EAC)between the gases and the nanoparticles was calculated based on the results of the nonequilibrium molecular dynamics(NEMD)simulations.The apparent thermal conductivity(ATC)of the gases between the heat source and heat sink was also obtained.The effects of the temperature,the particle diameter and the molecule type on the EAC and the ATC were investigated.The results indicate that the EAC decreases with the increase of temperature within the calculating range.When the preset temperature is constant,the EAC increases with the increasing of the particle diameter and eventually approaches a specific value.When the preset temperature is 300 K and the particle size is 4 nm,the obtained EAC for the N2 gas and the O2 gas is close to each other and both are less than that of the Ar gas.The results also indicate that the heat transferred through the gas-nanoparticle interface is far less than that through the neighbouring nanoparticles in silica aerogels.
展开▼
