A numerical analysis on the heat transfer of jet impingement with nanofluid on a concave surface covered with metal poro
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ORIGINAL
A numerical analysis on the heat transfer of jet impingement with nanofluid on a concave surface covered with metal porous block Wei Chen 1 & Jian Cheng 1 Received: 9 June 2018 / Accepted: 30 June 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract In this paper, combining the bilayer porous metal block of copper (BPMBC) on the concave heating surface and jet impingement of SiO2-H2O nanofluid is utilized in the flow channel. The k-ε turbulent model coupled with Brinkman Forchheimer extended Darcy equations are employed to analyze the effects of the SiO2-H2O nanofluid concentration, porosity in the porous monolayer on concave surface, thickness ratio between the upper and lower porous layer in the bilayer porous metal block as well as the curvature of concave surface on the heat transfer. In comparison with pure water as working fluid, the 5.85% rise of average heat transfer coefficient (HTC) can be obtained while the 3.0% SiO2-H2O nanofluid is utilized in the mode. The combining effects of the porosity in the monolayer porous layer and the curvature of concave surface on the heat transfer are related to the heating surface area and convection between the jet nanofluid and heating surface. More heat transfer occurs in the bilayer porous metal block with a larger porosity in the upper layer and a lower porosity in the bottom layer due to the dominant effects of the convection and thermal conductivity respectively in the different porous layers. The effects of the thickness ratio between the upper and lower layer in the bilayer porous metal block on the heat transfer are related to the influencing portion between the surface area and convection. With an increase in the curvature of concave surface from R/L(ratio of concave radius to chordal length) =0.5 to R/L = 1.1, the average Nusselt numbers go up, and their rise rates decrease by the Reynolds number gradually, but the surface area decreases, which causes the average temperature rise of copper block. Besides, the higher average temperature occurs in the mode with a flat plate than that with a concave surface. Keywords Numerical analysis . Jet impingement . Concave surface . Metal porous layer . Silica-water nanofluid
Nomenclature BPMBC Bilayer porous metal block of copper cε1 Constant for the turbulence model cε2 Constant for the turbulence model cμ Constant for the turbulence model cp Specific heat capacity, (J/kg.K) CUS Concave upper surface df Fiber diameter in porous metal foam, (m) dnp Nanoparticle diameter,(nm) dp Metal foam pore, (m) D Diameter of concave, (mm) F Inertia coefficient
* Wei Chen [email protected] 1
Merchant Marine College, Shanghai Maritime University, shanghai 201306, People’s Republic of China
Gk h HTC HTS H0 H1 H2 k keff, f keff, s kf knp kbf knf knfe
Turbulence model coefficient Convective heat transfer coefficient, (W/(m2K)) Heat transfer coefficient, (W/(m2K)) Heat transfer surface Height of flow channel, (mm) Height of copper block, (mm) Distance from nozzle to the concave surface, (mm) Turbulence
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