Graphene based nanofluids

H. Xie1 and W. Yu1

1Shanghai Second Polytechnic University, P.R. China

Keywords: nanocomposites
property: thermal conductivity
material: graphene

Nanofluids, which are the suspensions of nanoparticles in fluids, have tremendous potential applications in microelectronics, energy supply and transportation because of their intriguing properties such as considerable increase in thermal conductivity, long-term stability, and prevention of clogging in micro-channels. Graphene, a single-atom-thick sheet of hexagonally arrayed sp2-bonded carbon atoms, is a new kind carbon material, and it demonstrates many unique physical, chemical and mechanical properties, so it has attracted much attention since it was discovered in 2004. The extremely high value of the thermal conductivity suggests that graphene can outperform carbon nanotubes in heat conduction, and the property is beneficial for its application in thermal management, and it is expected to be a good additive of nanofluids. In this work, graphene oxide and graphene were prepared by oxidation-exfoliation-reduction method. Graphene oxide and surface-modified graphene have good compatibility with polar solvents. We prepared two kinds of ethylene glycol based nanofluids containing graphene oxide or graphene nanosheets, and the thermal conductivities of the nanofluids were measured by a transient short hot-wire technique. The results indicate that the two kinds of nanofluids have substantially higher thermal conductivities than the base fluids. The thermal conductivity enhancement ratios with the loading 5.0 vol.% are up to 61% and 86%, when the additives are graphene oxide and graphene, respectively. Graphene is a more efficient additive than graphene oxide for the enhancement of the thermal conductivity of nanofluids. The thermal conductivities depend strongly on the volume fraction of the additive, and the levels of enhancement are independent of temperatures under the measured conditions. The two-dimensional geometry, high aspect ratio and stiffness of graphene and graphene oxide are helpful to the outstanding thermal transport property of the pertaining nanofluids.

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