Effect of CuO-, SiO₂-, and Al₂O₃-based nanofluids on automotive cooling systems from laminar to turbulent flow regime—A CFD study

In recent studies, much attention has been given to nanofluids suggesting that adding nanoparticles in base fluids offers a higher heat transfer rate compared with conventional fluids. This study is based on the numerical investigation of different types of nanofluids, consisting of CuO (50 nm), SiO₂ (40 nm), and Al₂O₃ (15 nm) nanoparticles at different volume concentrations. Several simulations were performed from low to high Reynolds numbers, corresponding to laminar and turbulent flow regimes using ANSYS-Fluent CFD solver. Results suggest that under a laminar flow regime with the same Reynolds number of 2000, CuO-based nanofluids perform better as compared with SiO₂ and Al₂O₃-based nanofluids with Nusselt number (Nu) having percentage increase of 90% and 60% comparing with SiO₂- and Al₂O₃-based nanofluids, respectively. However, at higher Reynolds numbers when the flow is turbulent, Al₂O₃-based nanofluids demonstrate better performance having a percentage increase in Nusselt numbers equal to 40% and 23% as compared with CuO and SiO₂-based nanofluids respectively under the same Reynolds number of 15,000. This implies that turbulence has a significant effect on heat transfer rate, and is not only related to thermal conductivity. This study will help in designing more compact cooling systems for engines and the internal environment of motor vehicles.