| This work presents a numerical investigation into the hydrodynamic behavior and heat transfer enhancement capabilities of coolants with suspended metallic nanoparticules inside a typical radial flow cooling system. Considered nanofluids in this study include water/Al2O3 and ethylene glycol/Al 2O3 mixtures. The laminar forced convection flow of these nanofluids between two coaxial and parallel disks with central axial injection has been considered. The impinged disk is subjected to a constant heat flux. The study also considers the importance of the variation of nanofluid properties as a function of local temperature. Results clearly indicate that considerable heat transfer benefits are possible with the use of these fluid/solid particle mixtures. In general, heat transfer is enhanced with an increase in particle loading. Also, increases in Reynolds number, a reduction in the distance between disks and an increase in wall heat flux, all contributed to increasing heat transfer between the disk and the fluid. However, results also show that the presence of nanoparticules will also increase wall shear stresses. Indeed, results clearly indicate that wall shear stresses increase considerably with an increase in particle loading. Furthermore, results show that considerable differences are found when using constant property nanofluids (temperature independent) versus nanofluids with temperature dependent properties. The use of temperature-dependent properties yields greater heat transfer predictions with corresponding decreases in wall shear stresses when compared to predictions using constant properties. With an increase in wall heat flux, it was found that the average heat transfer coefficient increases whilst the wall shear stress decreases for cases using temperature-dependent nanofluid properties. |
