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Open AccessArticle

Numerical Investigation of Forced Convective Heat Transfer and Performance Evaluation Criterion of Al2O3/Water Nanofluid Flow inside an Axisymmetric Microchannel

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School of Mechanical Engineering, University of Tehran, Tehran 14155-6619, Iran
2
Faculty of Mechanical Engineering, Shahrood University of Technology, Shahrood 3619995161, Iran
3
CORIA-UMR 6614, Normandie University, CNRS-University & INSA, 76000 Rouen, France
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Department for Management of Science and Technology Development, Ton Duc Thang University, Ho Chi Minh City 758307, Vietnam
5
Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City 758307, Vietnam
*
Authors to whom correspondence should be addressed.
Symmetry 2020, 12(1), 120; https://doi.org/10.3390/sym12010120
Received: 6 December 2019 / Revised: 27 December 2019 / Accepted: 31 December 2019 / Published: 7 January 2020
(This article belongs to the Special Issue Future and Prospects in Non-Newtonian and Nanofluids)
Al2O3/water nanofluid conjugate heat transfer inside a microchannel is studied numerically. The fluid flow is laminar and a constant heat flux is applied to the axisymmetric microchannel’s outer wall, and the two ends of the microchannel’s wall are considered adiabatic. The problem is inherently three-dimensional, however, in order to reduce the computational cost of the solution, it is rational to consider only a half portion of the axisymmetric microchannel and the domain is revolved through its axis. Hence. the problem is reduced to a two-dimensional domain, leading to less computational grid. At the centerline (r = 0), as the flow is axisymmetric, there is no radial gradient (∂u/∂r = 0, v = 0, ∂T/∂r = 0). The effects of four Reynolds numbers of 500, 1000, 1500, and 2000; particle volume fractions of 0% (pure water), 2%, 4%, and 6%; and nanoparticles diameters in the range of 10 nm, 30 nm, 50 nm, and 70 nm on forced convective heat transfer as well as performance evaluation criterion are studied. The parameter of performance evaluation criterion provides valuable information related to heat transfer augmentation together with pressure losses and pumping power needed in a system. One goal of the study is to address the expense of increased pressure loss for the increment of the heat transfer coefficient. Furthermore, it is shown that, despite the macro-scale problem, in microchannels, the viscous dissipation effect cannot be ignored and is like an energy source in the fluid, affecting temperature distribution as well as the heat transfer coefficient. In fact, it is explained that, in the micro-scale, an increase in inlet velocity leads to more viscous dissipation rates and, as the friction between the wall and fluid is considerable, the temperature of the wall grows more intensely compared with the bulk temperature of the fluid. Consequently, in microchannels, the thermal behavior of the fluid would be totally different from that of the macro-scale. View Full-Text
Keywords: forced convection; axisymmetric microchannel; viscous dissipation; conjugate heat transfer; performance evaluation criterion; Al2O3/water nanofluid; CFD forced convection; axisymmetric microchannel; viscous dissipation; conjugate heat transfer; performance evaluation criterion; Al2O3/water nanofluid; CFD
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Irandoost Shahrestani, M.; Maleki, A.; Safdari Shadloo, M.; Tlili, I. Numerical Investigation of Forced Convective Heat Transfer and Performance Evaluation Criterion of Al2O3/Water Nanofluid Flow inside an Axisymmetric Microchannel. Symmetry 2020, 12, 120.

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