Analysis And Verification Of Nanofluid Transfer Performance In Microchannels

Current devices have high integration and small volume.Traditional cooling methods such as air cooling and liquid cooling are no longer suitable for microstructures.However,the advantages of small volume and strong heat dissipation capability of micro-channel dispersion have been widely concerned.The heat dissipation capacity of micro-channels mainly depends on the thermal physical properties of the fluids in the channels.Nanofluids are used as the heat dissipation fluid because of their higher thermal conductivity,stronger flow heat transfer and better stability than the micron-scale suspension compared with the traditional base liquid.In this paper,Al2O3-H2 O nanofluid is used as the research object,and the molecular dynamics method is used to simulate the thermal conductivity and viscosity of nanofluid at the micro scale,and the experimental means are used to verify the two physical parameters.The main research contents of this paper are as follows:(1)The viscosity and thermal conductivity of the base liquid were calculated by EMD and NEMD simulation methods to verify the accuracy of the simulation method.On this basis,the thermal conductivity and viscosity of the nanofluid were simulated and analyzed from the temperature,volume fraction and the shape parameters of the nanoparticles.The effects of the volume fraction,particle size and shape of nanoparticles on the viscosity and thermal conductivity of the nanofluid were discussed.The specific surface area was proposed to characterize the morphology of the nanoparticles.The simulation results showed that the thermal conductivity and viscosity of the base liquid increased after the addition of nanoparticles.(2)By analyzing the radial distribution function of the nanofluid,the results show that it still has the characteristics of "short-range disorder and long-range order",which indicates that the addition of nanoparticles does not change the properties of the fluid,but enhances the heat transfer ability of the fluid.In the simulation process,the temperature distribution and the movement of nanoparticles in the simulation system were determined by studying the temperature and density of each layer in the simulation area.(3)By building an experimental platform to measure the thermal conductivity and viscosity of nanofluids,and comparing with the simulated values,the feasibility of using molecular dynamics to simulate the physical properties of nanofluids was verified.The results show that the NEMD method is closest to the experimental value when simulating the thermal conductivity of fluid.When simulating fluid viscosity,EMD method is more suitable.