Investigating thermo-physical properties and thermal performance of Al2O3 and CuO nanoparticles in Water and Ethylene Glycol based fluids

The thermophysical properties and thermal performance of water- and ethylene-glycol-based nanofluids containing Al2O3 and CuO nanoparticles were examined. Nanofluids were prepared at four concentrations (1-4 vol%) using an electric mixer and magnetic stirrer, and the thermophysical properties were measured. Surfactants were used to improve stability. The transient hot-wire method (KD2-Pro device), Dynamic Light Scattering (DLS), and Ostwald viscometer (ASTM D445-06) were used to measure the resulting thermal conductivity coefficient, nanoparticle diameter, and nanofluid viscosity, respectively. The experiments were carried out in the 20 to 50 °C temperature range. Adding 1 wt% sodium dodecyl sulfate (SDS) to the CuO-water and the same amount of sodium dodecylbenzene sulfonate (SDBS) to the Al2O3-water nanofluid were found to stabilize them for 20 and 22 days, respectively. Increasing the nanoparticle volume fraction, raising the temperature, and reducing nanoparticle diameter were found to increase the thermal conductivity coefficient. The density also increases with the nanoparticle volume fraction in the base fluid increasing. Moreover, at the same volume fraction, the CuO-water nanofluid had a higher density than Al2O3-water. Better base fluid thermal properties amplify the effect on the nanofluid's thermal conductivity coefficient. The actual thermal conductivity coefficient was determined by comparing model predictions of the coefficient.