Thermophysical properties measurements and numerical modeling of nanofluids

Abstract

This thesis covers measurements of the thermo physical properties of various nanofluids containing copper oxide (CuO), silicon dioxide (SiO₂) and aluminum oxide (Al₂O₃) nanoparticles and numerical investigation on the fluid dynamic and heat transfer characteristics of nanofluids. Nanofluids are dispersions of nanometer-sized particles (<100 nm) in heat transfer liquids such as water, ethylene glycol or propylene glycol. An ethylene glycol and water (60:40 by mass) mixture was used as a base fluid in which various volume concentrations of nanofluids were dispersed. These nanofluids will be useful in the sub-arctic and arctic environments. Experiments were performed to investigate the rheological properties of CuO, SiO₂ and Al₂O₃ nanofluids. New viscosity correlations for different nanofluids as a function of volume concentration and temperature were developed. Using these correlations heat transfer performance of nanofluids as compared to the base fluid was numerically analyzed for laminar as well as for turbulent flows. Developing laminar flows in a parallel plate duct were computed for Reynolds number ranging from 100 to 2000 for various concentrations of CuO nanofluids. Turbulent convective heat transfer in circular tube geometry under a prescribed heat flux was numerically analyzed for Reynolds numbers ranging from 10⁴ to 10⁵. Heat transfer enhancement of various nanofluids over the base fluid was evaluated. The numerical results show enhanced heat transfer with increase in the volume concentration of nanoparticles.