Role of Brownian motion in the enhanced thermal conductivity of nanofluids

TLDR

The study aims to enable the design of nanoengineered coolants for high‑heat‑flux industrial and biomedical applications. A theoretical model incorporating dynamic nanoparticles was developed to explain nanofluid thermal behavior. Brownian motion is identified as the key mechanism driving enhanced thermal conductivity, and the model predicts concentration, temperature, and size‑dependent conductivity, revealing distinct behavior compared to solid composites.

Abstract

We have found that the Brownian motion of nanoparticles at the molecular and nanoscale level is a key mechanism governing the thermal behavior of nanoparticle–fluid suspensions (“nanofluids”). We have devised a theoretical model that accounts for the fundamental role of dynamic nanoparticles in nanofluids. The model not only captures the concentration and temperature-dependent conductivity, but also predicts strongly size-dependent conductivity. Furthermore, we have discovered a fundamental difference between solid/solid composites and solid/liquid suspensions in size-dependent conductivity. This understanding could lead to design of nanoengineered next-generation coolants with industrial and biomedical applications in high-heat-flux cooling.