Molecular dynamics simulation of effective thermal conductivity and study of enhanced thermal transport mechanism in nanofluids

Abstract

Nanofluids have been proposed as a route for surpassing the performance of currently available heat transfer liquids in the near future. In this study an equilibrium molecular dynamics simulation was used to model a nanofluid system. The thermal conductivity of the base fluid and nanofluid was computed using the Green-Kubo method for various volume fractions of nanoparticle loadings. This study showed the ability of molecular dynamics to predict the enhanced thermal conductivity of nanofluids. Through molecular dynamics calculation of mean square displacements for liquid phase in base fluid and for liquid and solid phases in nanofluid, this study tried to investigate the mechanisms involved in thermal transport of nanofluids at the atomic level. The result showed that the thermal transport enhancement of nanofluids was mostly due to the increased movement of liquid atoms in the presence of nanoparticle. Diffusion coefficients were also calculated for base fluid and nanofluids. Similarity of enhancement in thermal conductivity and diffusion coefficient for nanofluids indicates similar transport process for mass and heat.

Thermal behaviour of nanofluids confined in nanochannels

“…The volume fraction was varied by increasing the wall separation distance while keeping the size of the particle constant. The exponential nature of the curve differs and is in fact opposite from previous computational studies using the same nanofluids in their bulk form [10], in which the thermal conductivity presents a steeper gradient at the low volume fractions. The discrepancies between the results must therefore be attributed to the spatial restrictions imposed on the nanofluid.…”

“…It was, however, deemed insignificant due to the low frequency of collisions compared to the orders-of-magnitude larger thermal diffusion [8,5,7]. The motion of the nanoparticles was considered to affect the motion of the liquid, inducing nanoscale convective affects which transferring energy, with arguments both in favour [6,9,10] and against [11,8] its importance. Structured layers of liquid atoms located both, experimentally [12] and computationally [13] have been theorized to possess higher thermal conductivities due to their solid-like nature, significantly enhancing the overall heat transfer capacity of the fluid [14,15].…”

Nano-enhanced phase change materials for improved building performance

“…Babaei et al [48] used molecular dynamics simulation to investigate the thermal conductivity enhancement of paraffin with carbon based nano-fillers. Sarkar and Selvam [49] studied the enhanced thermal transport mechanism of nanofluids by using molecular dynamics simulation. Li et al [50] investigated molecular layering at the liquid-solid interface of nanofluids by equilibrium molecular dynamics simulation.…”

A Review of Thermal Conductivity Models for Nanofluids

“…Sarkar and Selvam [37] developed the nanofluids system that consist of a base fluid of argon and copper particles with various nanoparticles concentrations. They used an equilibrium molecular dynamics simulation to model this nanofluid system.…”