The Effect of the Liquid Layer Around the Spherical and Cylindrical Nanoparticles in Enhancing Thermal Conductivity of Nanofluids

Abstract

In this work, the equilibrium molecular dynamics (MD) simulation combined with the Green–Kubo method is employed to calculate the thermal conductivity and investigate the impact of the liquid layer around the solid nanoparticle (NP) in enhancing thermal conductivity of nanofluid (argon–copper), which contains the liquid argon as a base fluid surrounding the spherical or cylindrical NPs of copper. First, the thermal conductivity is calculated at temperatures 85, 85.5, 86, and 86.5 K and for different volume fractions ranging from 4.33% to 11.35%. Second, the number ΔN of argon atoms is counted in the liquid layer formed at the solid–liquid interface with the thickness of Δr = 0.3 nm around the NP. Finally, the number density n of argon atoms in this layer formed is calculated in all cases. Also, the results for spherical and cylindrical NPs are compared with one another. It is observed that the thermal conductivity of the nanofluid increased with the increasing volume fraction and the number ΔN. Likewise, the thermal conductivity of nanofluid containing spherical NPs is higher than that of nanofluid containing cylindrical NPs. Furthermore, the number density n of argon atoms near the surface of spherical NPs is higher than that of argon atoms attached in the curved surface of cylindrical NPs. As a result, the liquid layer around the solid NP has been considered one of the mechanisms responsible contributing to the thermal conductivity enhancement in nanofluids.

Thermal conductivity of nanofluids formed by carbon flurooxide mesoparticles

“…7 (see continuous lines) and experimental data from Fig. 4b) allows to conclude on a key role of the interface nanolayer [45] in thermal transport of the CFO-based nanofluids.…”

Coupling at the molecular scale between the graphene nanosheet and water and its effect on the thermal conductivity of the nanofluid

“…It is widely accepted that this is among the possible mechanisms of enhancing thermal conductivity on a microscopic scale. 23,24,28 At approximately 15 A from the GNS surface, the water density converges to the normal bulk value ( ρ ≈ 0.98 g cm −3 ), indicating that the change in the thermal conductivity of water only occurs within the range of 1–2 nm from the interface.…”

“…It is widely accepted that this is among the possible mechanisms of enhancing thermal conductivity on a microscopic scale. 23,24,28 At approximately 15 A from the GNS surface, the water density converges to the normal bulk value (r E 0.98 g cm À3 ), indicating that the change in the thermal conductivity of water only occurs within the range of 1-2 nm from the interface. On one hand, the interaction between graphene and water not only induces an ordered water layer structure on the GNS surface, on the other hand, the thermal conductivities of graphene in water can also be influenced by its interaction with water molecules.…”

“…26,27 Sarkar et al 22 found that the motion of fluid molecules was enhanced in the presence of nanoparticles so that heat transport in nanofluids was strengthened. Loulijat et al 28 proposed that the liquid layer around the surface of solid nanoparticles was one of the factors leading to a significant enhancement in the thermal conductivity of nanofluids. Guo et al 29 demonstrated that the interfacial layer plays a crucial role in predicting the thermal conductivity of nanofluids.…”

Synthesis and Characterization of Novel Ternary Hybrid Nanoparticles as Thermal Additives in H2O

“…Liquid layering will be dissimilar, and their interaction would be different for different shapes of nanoparticles. Spherical nanoparticles will have the spherical shape of liquid layers, while other shapes will be different [35]. iv.…”