Investigation of Structural Stability, Dispersion, Viscosity, and Conductive Heat Transfer Properties of Functionalized Carbon Nanotube Based Nanofluids

The present work investigates the structural stability, dispersion, viscosity, and convective heat transfer properties of nanofluids based on multiwalled carbon nanotubes (MWCNT). Oxidative acid refluxation on MWCNT was examined for different time periods in order to achieve good dispersibility and thermal enhancement. Structural stability and efficient chemical functionalization was investigated by thermogravimetric analysis. Fourier transform infrared spectroscopy was conducted to ascertain the formation of chemical functional groups on covalently modified MWCNT. Raman band study on oxidized MWCNT was analyzed by Raman scattering measurements. Dispersion of functionalized MWCNT was studied by ultraviolet–visible spectroscopy. Field emission scanning electron microscopy and transmission electron microscopy have been performed to ascertain the structural durableness of nanomaterials in fluids. Viscosity and thermal conductivity behavior of DI water and ethylene glycol based MWCNT nanofluids were studied with varied volume fractions and temperature (30–70 °C). Further, steady-state forced convective heat transfer experiments have been conducted to estimate the cooling capabilities of above-mentioned nanofluids.