Thermo-physical properties of water-based single-walled carbon nanotube nanofluid as advanced coolant

• The SWCNTs-nanofluids were prepared with highly dispersion stability.
• The thermo-physical properties of SWCNTs-nanofluids were measured and discussed.
• Thermal conductivity of SWCNTs-nanofluid is enhanced by 16.2%.
• The SWCNTs-nanofluid exhibits good heat transfer enhancement in laminar regime.
• The viscosity increase worsens heat transfer performance in turbulent regime.

In this paper, the thermo-physical properties of water-based single-walled carbon nanotube nanofluids (SWCNTs-nanofluids) are experimentally studied. The effect of mass concentration, varying from 0.1 to 1 wt%, on the thermal conductivity, viscosity and density of nanofluids is investigated at the temperatures of 10–60 °C. The results show that the thermal conductivity, viscosity and density of nanofluids are higher than that of the base fluid, and increase with an increase in nanotubes concentration. The thermo-physical property variation of SWCNTs-nanofluids with temperature is similar to that of pure water, i.e. thermal conductivity increases, whereas the viscosity and density decrease with an increase in the temperature. When the concentration is 1 wt%, at 60 °C, the maximum thermal conductivity and viscosity enhancements increase by up to 16.2% and 35.9%, respectively. Furthermore, the heat transfer performance of SWCNTs-nanofluids as advanced coolants is evaluated in both laminar and turbulent flow regimes based on the measured data. The evaluated results indicate that SWCNTs-nanofluids have good heat transfer performance in laminar flow regime. For the case of turbulent flow regime, however, the viscosity increase worsens the heat transfer performance at the lower temperature and higher concentration.