Determination of thermal conductivity of interfacial layer in nanofluids by equilibrium molecular dynamics simulation

•Green-Kubo theory is developed to evaluate thermal conductivity.•The thickness and thermal conductivity of interfacial layer are studied.•The effect of particle size and liquid-solid interaction are discussed.•Contribution of interfacial layer are considered in Modified Maxwell model. In this article, equilibrium molecular dynamics are performed to investigate the thickness and thermal conductivity of interfacial layer around the nanoparticle in dilute nanofluids. A nanofluids system of a 1-nm-diameter copper spherical nanoparticle immersing into argon base liquids and then a flat interface formed by liquid argon on the solid copper surface are studied. Green-Kubo formula is developed to calculate thermal conductivity of interfacial layer. Besides, the effect of solid-liquid interaction is studied. The nano-scale thin interfacial layer with more ordered structure and higher thermal conductivity than that of the base fluids is observed. Then the simulation results are incorporated into the modified Maxwell equation to calculate the effective thermal conductivity of nanofluids. The results indicate that the contribution of interfacial layer to thermal conductivity enhancement of nanofluids can be neglected.