Heat Transfer And Flow Properties Of Fe3O4-H2O Nanofluids Based On Molecular Dynamics

The thermal management parameters of traditional heat dissipation devices and fluids with low thermal conductivity have been difficult to meet the heat dissipation requirements of current high heat flux devices as electronic devices have become more miniaturized and integrated,which has had a significant impact on chip performance and reliability during operation.Microchannel heat dissipation devices with small volumes and nanofluids with high heat dissipation performance are thought to be an effective solution to the heat dissipation problem of high heat flux devices with limited area.Two important thermophysical parameters used in heat transfer scenarios are the viscosity and thermal conductivity of a unique kind of nanofluid for heat dissipation,which are related to the transportation efficiency and heat dissipation efficiency of heat dissipation equipment.With the addition of nano-scale particles,the fluid takes on unexpected properties,making it difficult to see its mechanism experimentally.Changes in several thermophysical characteristics of the fluid are therefore difficult to predict using the macroscopic suspension formula.As a result,this work uses molecular dynamics to simulate and calculate the transport parameters and mechanism of nanofluids,with Fe₃O₄-H₂O nanofluids as the research object.The following are the important research findings from the paper:（1）When the MD approach was used to simulate and assess the thermal conductivity of Fe₃O₄-H₂O nanofluid,the effect of simulated conditions on the change of thermal conductivity was explored.The estimated values of thermal conductivity of Fe3O4-H2O nanofluid showed an increasing trend as temperature and volume percent increased.The heat conductivity of the system improves when the particle size decreases,the number grows,and the specific surface area increases under the same conditions.A two-step process was used to make nano-fluids,and their thermal conductivity was measured and compared to the MD simulation findings,proving that the MD simulation results were accurate.（2）When the viscosity of Fe₃O₄-H₂O nanofluids is calculated using the MD method,the viscosity of the nanofluids falls as the temperature rises.The relative viscosity increases with temperature,and the overall increase tendency,as compared to the lowest condition temperature（290K）.The viscosity and relative viscosity of the nanofluid increase as the volume fraction of the system increases.The relative viscosity of the nanofluid is further increased after selecting nanoparticles with greater specific surface area,which is consistent with the effect of specific surface area on the viscosity of the nanofluid.（3）After the addition of nano-particles,the base liquid will form a liquid adsorption layer on the surface of the particles,indicating that the structure and properties of the nano-fluid change with respect to the base liquid,based on the radial distribution function of the nano-fluid and the number density of the base liquid near the particles.We also investigated the diffusion coefficient of nano-fluid and discovered that the addition of particles in the base liquid increased the diffusion coefficient,and that as temperature increased,the diffusion coefficient increased in the same way that the diffusion coefficient of liquid water changed.