Enhanced Mass Transport in Nanofluids

TLDR

Thermal conductivity enhancement in nanofluids is attributed to localized convection arising from nanoparticles’ Brownian motion. The study aims to visualize dye diffusion in nanofluids to investigate the analogy between convection and mass transfer. Dye diffuses faster in nanofluids than in water, peaking at a 0.5 % nanoparticle volume fraction; at this concentration the thermal‑conductivity slope change indicates convection diminishes, and the resulting enhanced mass transfer could benefit microfluidic device diffusion.

Abstract

Thermal conductivity enhancement in nanofluids, which are liquids containing suspended nanoparticles, has been attributed to localized convection arising from the nanoparticles' Brownian motion. Because convection and mass transfer are similar processes, the objective here is to visualize dye diffusion in nanofluids. It is observed that dye diffuses faster in nanofluids compared to that in water, with a peak enhancement at a nanoparticle volume fraction, phi, of 0.5%. A possible change in the slope of thermal conductivity enhancement at that same phi signifies that convection becomes less important at higher phi. The enhanced mass transfer in nanofluids can be utilized to improve diffusion in microfluidic devices.