Molecular Dynamics Simulation Of Transport Characteristics Of Nanofluids

The more important parameters of transport characteristics for liquid are thermal conductivity and viscosity. The more higher thermal conductivity is, the more excellent heat transfer is and the more viscosity is, the more higher transport cost is. Technology of heat transfer and cooling with high efficiency are restricted by lower heat transfer characteristics of conventional liquids, so developing fluids with more higher thermal conductivity and lower viscosity is the key point for technical breakthrough. Nanofluids which is created by adding solid particles with typical size under 100 nanometer into liquids have higher thermal conductivity that give the thought for developing of new type heat transfer working fluids. Although viscosity of nanofluids will be higher, but at low nanoparticle loading, the advantage of higher thermal conductivity is more than the disadvantage of increased viscosity which make nanofluids have more economic benefits and applied value.In present work, the characteristics of nanofluids are simulated using equilibrium molecular dynamics simulation method. Different factors are included in the simulation of Cu-Ar and Cu-H2O nanofluid system, such as temperature, volume fraction, diameter, quantity and potential parameters of nanoparticle, the enhancement mechanism of thermal conductivity of nanofluid is also investigated at the same time.The conclusions are listed as follows. Thermal conductivity and viscosity of nanofluids both increase with increased volume fraction of nanoparticle; Thermal conductivity of nanofluid increase with increased temperature but viscosity decrease; The smaller diameter of nanoparticle is, the stronger the enhancement of thermal conductivity will be, but viscosity is not changed much; Thermal conductivity and viscosity both increase with increased number of nanoparticle (aggregation is not included); Thermal conductivity of nanofluids increase with increased potential parameters of nanoparticle, but viscosity is not changed much.The arrangement of liquid atom near the nanoparticle is changed, thin layer with thickness of 6A is formed on the surface of nanoparticle because of strong force between particle and liquid, that is the main reason of which the enhancement is more bigger than the prediction of theory model of thermal conductivity of nanofluids.