(191t) Hydrophobic Nanoparticles for Nanofluids

Nanofluids are heat transfer fluids such as water, ethylene glycol, and oils that are engineered by dispersing nanoparticles with diameter less that 100 nm. By adding nanoparticles into the heat transfer liquid the overall heat transfer coefficient increases substantially above that of the base fluid. The biggest challenge of nanofluids is the formation of aggregates and in order to avoid that, stable suspensions are required. In this poster we will present a new method for depositing different hydrophobic coatings on the surface of particles in order to stabilize them in different coolant liquids (e.g. pump oils, ethylene glycol, and dibenzytoluene). Then we discuss the nanofluid stability and the coating properties. Nanometer-sized powders of silica and copper oxide are coated in a plasma reactor, which is capacitively coupled by a radio frequency generator (13.56 MHz) and works at 30 watts. Variety of hydrocarbons (e.g. isopropyl alcohol, toluene, perfluorooctane, and heptane) is used as the plasma reaction precursor that coats nanoparticles. One of the most important advantages of our method is that we coat particles in dry state, therefore we are able to mix particles with any liquids (e.g. 1-butanol, toluene, ethylene glycol, polyethylene glycol, and water). We have measured size of the particles and their stability using dynamic light scattering (DLS), zeta potential, and transmission electron microscopy (TEM). Dry particles can be dispersed in most of the liquids and coated particles show more stability in oily phase because of their hydrophobic surfaces.