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

Abstract

Abstract This paper examines the turbulent hydrothermal performance of boehmite/water–ethylene glycol $$(\upgamma -\mathrm{AlO}(\mathrm{OH})/{\mathrm{H}}_{2}\mathrm{O}-\mathrm{EG})$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mo>(</mml:mo><mml:mi>γ</mml:mi><mml:mo>-</mml:mo><mml:mi>AlO</mml:mi><mml:mrow><mml:mo>(</mml:mo><mml:mi>OH</mml:mi><mml:mo>)</mml:mo></mml:mrow><mml:mo>/</mml:mo><mml:msub><mml:mi>H</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:mi>O</mml:mi><mml:mo>-</mml:mo><mml:mi>EG</mml:mi><mml:mo>)</mml:mo></mml:mrow></mml:math> nanofluid flowing through a square duct fitted with various coiled-wire inserts (CWIs) using the finite volume method. The turbulent flow of $$\upgamma -\mathrm{AlO}(\mathrm{OH})/{\mathrm{H}}_{2}\mathrm{O}-\mathrm{EG}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>γ</mml:mi><mml:mo>-</mml:mo><mml:mi>AlO</mml:mi><mml:mrow><mml:mo>(</mml:mo><mml:mi>OH</mml:mi><mml:mo>)</mml:mo></mml:mrow><mml:mo>/</mml:mo><mml:msub><mml:mi>H</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:mi>O</mml:mi><mml:mo>-</mml:mo><mml:mi>EG</mml:mi></mml:mrow></mml:math> nanofluid is modeled using single-phase and $$k-\varepsilon$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>k</mml:mi><mml:mo>-</mml:mo><mml:mi>ε</mml:mi></mml:mrow></mml:math> model. A parametric study is carried out on the effect of Reynolds number ( $$5.0\times {10}^{3}\le \mathrm{Re}\le 4.0\times {10}^{4}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>5.0</mml:mn><mml:mo>×</mml:mo><mml:msup><mml:mrow><mml:mn>10</mml:mn></mml:mrow><mml:mn>3</mml:mn></mml:msup><mml:mo>≤</mml:mo><mml:mi>Re</mml:mi><mml:mo>≤</mml:mo><mml:mn>4.0</mml:mn><mml:mo>×</mml:mo><mml:msup><mml:mrow><mml:mn>10</mml:mn></mml:mrow><mml:mn>4</mml:mn></mml:msup></mml:mrow></mml:math> ), the geometry of wire (circular, triangular, square, square-diamond, hexagon, octagon, and decagon), nanoparticle volume ratio ( $$0\le \varphi \le 4\%$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>0</mml:mn><mml:mo>≤</mml:mo><mml:mi>φ</mml:mi><mml:mo>≤</mml:mo><mml:mn>4</mml:mn><mml:mo>%</mml:mo></mml:mrow></mml:math> ), 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 $$\mathrm{Re}=5.0\times {10}^{3}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Re</mml:mi><mml:mo>=</mml:mo><mml:mn>5.0</mml:mn><mml:mo>×</mml:mo><mml:msup><mml:mrow><mml:mn>10</mml:mn></mml:mrow><mml:mn>3</mml:mn></mml:msup></mml:mrow></mml:math> , the square CWI has the highest normalized $${\mathrm{Nu}}^{\mathrm{G}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mrow><mml:mi>Nu</mml:mi></mml:mrow><mml:mi>G</mml:mi></mml:msup></mml:math> (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 $${\mathrm{Nu}}^{\mathrm{N}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mrow><mml:mi>Nu</mml:mi></mml:mrow><mml:mi>N</mml:mi></mml:msup></mml:math> (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 $$\mathrm{Re}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>Re</mml:mi></mml:math> , as the values of their hydrothermal performance evaluation criteria are greater than unity.

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