Hydrothermal performance of a turbulent nanofluid with different nanoparticle shapes in a duct fitted with various configurations of coiled-wire inserts

Abstract

This paper examines the turbulent hydrothermal performance of boehmite/water–ethylene glycol (upgamma -mathrm{AlO}(mathrm{OH})/{mathrm{H}}_{2}mathrm{O}-mathrm{EG}) nanofluid flowing through a square duct fitted with various coiled-wire inserts (CWIs) using the finite volume method. The turbulent flow of upgamma -mathrm{AlO}(mathrm{OH})/{mathrm{H}}_{2}mathrm{O}-mathrm{EG} nanofluid is modeled using single-phase and k-varepsilon model. A parametric study is carried out on the effect of Reynolds number (5.0times {10}^{3}le mathrm{Re}le 4.0times {10}^{4}), the geometry of wire (circular, triangular, square, square-diamond, hexagon, octagon, and decagon), nanoparticle volume ratio (0le varphi le 4%), and nanoparticle shapes (blade, brick, cylinder, platelet, and oblate-spheroid) on hydrodynamic and convective heat transfer performance (CHTP). The results showed that the combination between CWI and nanofluid enhances hydrothermal performance. For instance, among the geometries of CWI considered at mathrm{Re}=5.0times {10}^{3}, the square CWI has the highest normalized {mathrm{Nu}}^{mathrm{G}} (referencing empty channel) of 2.58, while the decagon has the lowest value of 1.78. Furthermore, regarding the nanoparticle shapes, the platelet shape has a maximum normalized {mathrm{Nu}}^{mathrm{N}} (referencing base fluid) of 1.53, while the oblate-spheroid has a minimum value of 0.93. Lastly, in terms of application, square and octagon wire-fitted channels are better than empty channel at low mathrm{Re}, as the values of their hydrothermal performance evaluation criteria are greater than unity.