The role of interfacial nanolayer in the enhanced thermal conductivity of carbon nanotube-based nanofluids

Nanofluid, a new class of solid/liquid mixtures, provided theoretical challenges because the measured effective thermal conductivity containing a few loadings of nanoparticle (<5 vol%) showed greater enhancement than traditional models predicted. The solid-like nanolayer around the nanoparticle acts as a thermal bridge between the particle and the base fluid, so is a key mechanism to enhance heat transfer of nanofluid. Based on the two-dimension Fourier’s law in the cylindrical coordinates, we deduced an expression for calculating the effective thermal conductivity of carbon nanotube-based nanofluid considering the interfacial nanolayer, as well as an empirical shape factor. The theoretical predictions on the enhanced thermal conductivity agree quite well with the available experimental data.