Impact of sonication durations on thermophysical properties, contact angle and surface tension of f-MWCNTs nanofluid for heat transfer

Several reports have shown the potential of nanofluids in enhancing the performance of heat transfer applications. Multi-walled carbon nanotubes are getting substantial attention among researchers due to their excellent characteristics such as increased thermal conductivity. Functionalizing MWCNTs using COOH functional groups creates the carbon nanotubes hydrophilic; improves nanofluids' stability. The current experimental study used XRD and BET to characterize nanoparticles and investigates the effect of sonication duration and effect of three volume concentrations (0.05, 0.10, and 0.30 vol.%) of functionalized-multi walled carbon nanotubes (f-MWCNTs/water) nanofluid on stability and thermal conductivity, specific heat, contact angle, and surface tension. Referring to experimental findings, the volume concentration of 0.10 vol% shows the maximum and long-term stability (-39.84 mV) for 80 minutes of sonication duration. With increasing sonication time, the particle size becomes smaller, and 0.30 vol% concentration showed considerable variation. At sonication time of 20 minutes, the maximum thermal conductivity improvement was reported at 5.90% at 0.10 vol% and a temperature of 50 degrees C, while the maximum enhancement in specific heat (4.12%) has been reported for 0.30 vol.% concentration. The surface tension and contact angle reduced with rising volume concentration. In conclusion, the optimum volume concentration of 0.10 vol.% has been reported for better stability and enhanced thermal conductivity. This paper shall provide greater insight for the researcher to incorporate the optimum sonication duration and its effect on nanofluids' stability and thermophysical properties. (c) 2022 Elsevier B.V. All rights reserved.

Automated summary

This study investigates the effect of functionalized-multi walled carbon nanotubes (f-MWCNTs/water) nanofluid on stability and thermophysical properties. The results show that the optimum volume concentration of 0.10 vol.% exhibits the best stability and enhanced thermal conductivity. The research provides insights for incorporating the optimum sonication duration in nanofluid studies.