On the Influencing Factors and Strengthening Mechanism for Thermal Conductivity of Nanofluids by Molecular Dynamics Simulation

Compared with conventional single-phase working fluids, nanofluids possess significantly increased thermal conducting properties, but the mechanism for the increase still lacks perfect theory to explain. The aim of this study was to investigate effects of various influencing factors and determine the strengthening mechanism for thermal conductivity of nanofluids by Molecular Dynamics simulations. Thermal conductivities of nanofluids containing nanoparticles with different materials, volume concentrations, and shapes were calculated based on the Green-Kubo formula. Besides, Radical Distribution Function was first applied to nanofluids to analyze the microstructure. In addition, micromotions of nanoparticles were investigated thoroughly by statistical analysis. It was found for the first time that the effects of influencing factors for thermal conductivity of nanofluids can be explained and forecasted by comparing the proportion of energetic atoms containing in different nanoparticles. The changed microstructure of nanofluids is a newly discovered mechanism, and combined with the micromotions of nanoparticles they are proposed to be the main mechanism for strengthening thermal conductivity of nanofluids. The present work indicates that analyzing the proportion of energetic atoms can be an effective way for predicting thermal conducting properties of nanofluids and suggests the main mechanism for thermal conductivity increase which is the basis of developing new heat transfer theory for nanofluids.