Surfactant-free ionic liquid-based nanofluids with remarkable thermal conductivity enhancement at very low loading of graphene
1 Key Laboratory of Enhanced Heat Transfer and Energy Conservation, the Ministry of Education, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, 510640, China
2 School of Materials Science and Engineering, South China University of Technology, Guangzhou, 510640, China
Nanoscale Research Letters 2012, 7:314 doi:10.1186/1556-276X-7-314Published: 19 June 2012
We report for the first time the preparation of highly stable graphene (GE)-based nanofluids with ionic liquid as base fluids (ionic liquid-based nanofluids (Ionanofluids)) without any surfactant and the subsequent investigations on their thermal conductivity, specific heat, and viscosity. The microstructure of the GE and MWCNTs are observed by transmission electron microscope. Thermal conductivity (TC), specific heat, and viscosity of these Ionanofluids were measured for different weight fractions and at varying temperatures, demonstrating that the Ionanofluids exhibit considerably higher TC and lower viscosity than that of their base fluids without significant specific heat decrease. An enhancement in TC by about 15.5% and 18.6% has been achieved at 25 °C and 65 °C respectively for the GE-based nanofluid at mass fraction of as low as 0.06%, which is larger than that of the MWCNT-dispersed nanofluid at the same loading. When the temperature rises, the TC and specific heat of the Ionanofluid increase clearly, while the viscosity decreases sharply. Moreover, the viscosity of the prepared Ionanofluids is lower than that of the base fluid. All these advantages of this new kind of Ionanofluid make it an ideal fluid for heat transfer and thermal storage.