Comparative Study on Convection and Wall Characteristics of Al<sub>2</sub>O<sub>3</sub>-water Nanofluid Flow inside a Miniature Tube
Keywords:Convective heat transfer, nanofluids, computational fluid dynamics, shear stress, temperature-dependent properties, dispersion model.
Forced convective heat transfer and wall characteristics of nanofluid flow containing Al2O3 nanoparticles and water inside a miniature tube are studied by means of computational fluid dynamic (CFD) code. Problem is solved by employing finite volume approach and using both single-phase (homogeneous) and dispersion models. In both models, constant and temperature-dependent thermophysical properties are used and obtained results are compared with results of other literature. It can be seen as the Reynolds number increases, the Nusselt number improves, too. However, it is accompanied by higher wall shear stress. Moreover, in the case of temperature-dependent properties, lower values for shear stress were obtained. In comparison with experimental data and available theoretical correlations, dispersion model in both temperature-dependent and constant properties shows good agreement. On the other hand, single-phase model employing constant thermophysical properties underestimates the amount of convective heat transfer. Furthermore, it can be observed by increasing the particle volume concentration, not only the wall temperature decreases, also the rate of thermal enhancement decreases slightly.
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