Molecular Simulation Of Thermophysical Properties Of Phase Change Materials

Phase change material NaNO₃/KNO₃ mixed salt is widely used in solar thermal power generation system because of its suitable phase transition temperature range?200-300??,and it has the advantages of high latent heat and cheap price,but the thermal conductivity of nitrate is relatively small,and it has great influence on the heat storage speed of the system,and it is based on graphene.In addition,the phase change materials composed of the fused salt in the graphene can greatly increase the thermal conductivity,thus reduce the time spending on energy storage and release,and improve the efficiency of the energy use.The energy,density and heat of the phase change materials are analyzed and analyzed by molecular dynamics simulation,combined with the related modules of Materials studio molecular simulation software,with NaNO₃,different proportion of binary NaNO3/KNO3 mixed salt,solar salt,graphene/solar salt composite phase change material,composite phase change material of sodium nitrate graphene.The related physical and thermal parameters such as capacitance,melting point and thermal conductivity were analyzed,and the structural changes in phase change process of phase change materials were analyzed.The main work is:?1?molecular dynamics simulation of one element nitrateThe sodium nitrate?NaNO₃?in eutectic salt was used as the research object.The sodium nitrate molecular model was constructed by MS software,and the accuracy of the model was verified by the Reflex module.Then the energy,density,specific heat capacity of the sodium nitrate in phase change material were studied with the aid of MS software with the aid of molecular dynamics.Debye temperature,thermal conductivity and other thermophysical parameters and their simulation with temperature change.?2?Study on NaNO3/KNO3 mixed eutectic saltThe thermophysical parameters of phase change material NaNO₃/KNO₃ mixed eutectic nitrate and the molecular microstructure during phase transformation were studied.The theoretical calculation of the liquidus temperature,the solid phase temperature and the latent heat of the mixed eutectic salt with different proportions ofNaNO₃/KNO₃ was first studied.Then the kinetic energy and density of the mixed eutectic salt were studied.Finally,the solar salt was studied and the melting point of the solar salt was predicted by the mean square displacement.By analyzing the intermolecular radial distribution function,we further explore the change of molecular microstructure during eutectic salt phase transformation.?3?molecular simulation of composite phase change materialsThe adsorption and diffusion of molten solar salt on graphene surface were simulated,and the mean square displacement of adsorption energy and diffusion process was calculated.The thermal conductivity of the phase change material is studied.The thermal conductivity of the phase change material is studied.The thermal conductivity of the composite phase change material of graphene nitrate is calculated.The composite phase change material with Shi Moxi can increase the thermal conductivity of sodium nitrate significantly.