Experimental investigation on stability and thermal conductivity of dodecanethiol-coated copper nanofluids

Nanofluids were prepared by dispersing dodecanethiol-coated copper nanoparticles (similar to 50 nm average diameter) in toluene. The stability and thermal conductivity of the nanofluids were investigated for various particle volume concentrations (0.09-1.5 vol%) and temperatures (293-333 K). The amount of dodecanethiol surfactant coated on the nanoparticle surface was determined by thermogravimetric analysis (TGA), and the chemical structure of adsorbed surfactant molecules was characterized by Fourier transform infrared spectroscopy (FT-IR). UV-vis absorbance analysis of the nanofluid was undertaken to determine the optimum ultrasonic vibration time for stability enhancement. The modeling study generated a new semi-practical correlation as a function of particle volume concentration and temperature for an existing Brownian motion-based thermal conductivity model, which demonstrated good compatibility with the present experimental measurements compared with other models.