Optimization of Forced Convection Heat Transfer Using ZnO-Water Nanofluid in a Square Cross-Section 3D Channel: A Numerical Investigation

Abstract

The improvement of the performance of thermal systems is an important task in today's energy industry, for example, in solar collectors and solar heat exchangers. The enhancement of heat transfer and fluid dynamics inside different channel geometries is therefore of high technological and scientific interest. In this regard, exploitation of nanofluids has gained attention as an alternative strategy to improve thermal performance, as they possess better thermophysical properties. Current work is based on computational fluid dynamics (CFD) tools (Ansys Fluent) to enhance the heat transfer and the flow behavior of water by ZnO nanoparticles, also known as zinc oxide. Nanoparticles of zinc oxide (ZnO) are dispersed in the water at varying concentrations (0.4% and 1.3%) in a channel having a square cross section. The bottom face is maintained under a constant heat flux of 50kW/m² and the rest of the walls are thermally insulated. The flow is assumed to be turbulent, single-phase, steady, 3D, and occurring in the range of Reynolds number from 4000 to 12000. The results indicate that the incorporation of ZnO nanoparticles can effectively enhance heat transfer, and the heat transfer coefficients increase by 23.79% and 28.10% when the volume fractions are 0.4% and 1.3%, respectively. In addition, the friction factor is reduced with a higher Reynolds number and by adding nanoparticles. These results indicate that not only can ZnO nanofluids greatly enhance the system performance.