The Gas-solid Coupling Study In Confined Nano-scale Interspace By Molecular Dynamics Simulation

The promising nanoporous materials attracted serious concern in the scientific and engineering field.Because of the unique structure of nanoporous materials,the thermal and mechanical research are still in the beginnin g stage.Starting from the description of motion behavior of gas in confined nano st ructure and interaction analysis between gas molecule and nano grain solid surfac es,this project is to study the heat and mass transfer mechanism of gas in confined n ano-scale interspace by theoretical analysis and simulation.Based on the molecul ar dynamics theory and surface theory,we build solid-gas interface model and defect gap structure model and use the software lammps to do a lot of simulations in different situations.We change the parameters of the potential energy to investigate the different factors which will affects the thermal conductivity and explain the mechanism of the heat transfer.The results shows that when potential energy is sufficiently large,the gas will be absorbed in the surface of the solid and the thickness will increase with potential energy increases.Actually,the heat transfer happened in the adsorption layer.When the potential energy increases,the time of operation and the thermal conductivity will increase.The heat transfer efficiency of interface ? will increases with potential energy increases,until the maximum theorical value 1.44MW/m2 K.Because of the adsorption layer,the energy exchange will increase in the horizon axis and it is good for thermal conductivity,Within the 200-600 K range,the thermal conductivity of defect structure will decrease in 38% and 47% for graphene and carbon nanotube.The defect of structure will lead the participation decreasing for different phonon mode.However,due to the dispersion effect in boundary,the extent in graphene wil l less than carbon nanotube.The thermal current will have different efforts in different direction.The proportion of heat current of y direction in graphene and z direction in nanotube will increase.