A Simple Approach for Heat Transfer Enhancement of Carbon Nanofluids in Aqueous Media.

Nanofluids are considered alternative heat transfer fluids because of their excellent thermal and electronic conductivities. Recently, carbon nanomaterials such as carbon nanotubes and graphene have been considered to fabricate enhanced heat transfer nanofluids, but using them to prepare stable nanofluids remains challenging because of their hydrophobicity. Herein, a stable aqueous graphene and carbon nanotube dispersion was prepared using nanostructured cellulose without any additional chemicals. The dispersibility of graphene in cellulose was compared with that in conventional surfactants such as sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, and lauryl betaine. In addition, the optimal mass ratio for the carbon material to cellulose was determined and improvement in the thermal and electrical conductivity of the nanofluid was investigated. The dispersion ability of cellulose was more significant than that of surfactants, and it played a major role in improving the thermal and electrical conductivity. The highest thermal conductivity obtained for the graphene-cellulose nanofluid was 615.23 W/m*K for a mass ratio of 2:1 at 20 °C. The electrical conductivity of the nanofluids increased remarkably with an increase in the cellulose content. Furthermore, the obtained nanofluid improved the heat transfer performance dramatically. It can be assumed that our proposed system can be used to ensure numerous economic and environmental benefits in the domain of heat transfer fluids.