In the past twenty years, the behavior of the apparent thermal conductance of two or three phase systems comprised of solid particles with nanometer dimensions suspended in fluids, dubbed nanofluids, has been greatly contested in literature. After the study of the seven simplest nanofluids, Cu, CuO, Al2O3, and TiO2 suspended in water and ethylene glycol, ...
The authors present a method of preparation of TiO2 nanotubes by alkaline treatment (with NaOH) of TiO2 particles followed by acid-washing and annealing treatment. Theoretical and experimental studies on the thermal conductivity of TiO2 nanotubes is also presented. The thermal conductivity values determined experimentally matched well with theoretical values obtained. It was found that TiO2 nanotubes had a lower thermal conductivity than the original TiO2 particles. This phenomenon was attributed ...
This study looks at the effects of pH on heat transfer, among other things, of nanofluids. Over 20% enhancement of thermal conductivity was noted with nanofluids containing 3wt% zirconium dioxide and titanium dioxide. Also noted, was the influence of pH on the stability of the nanofluids. The Derjaguin-Landau-Verwey-Overbeek theory states that nanoparticles become unstable, form clusters and precipitate, when their pH is near the isoelectric point. This leads to large clusters ...
