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Energies 2017, 10(7), 1065; doi:10.3390/en10071065

Effects of Anisotropic Thermal Conductivity and Lorentz Force on the Flow and Heat Transfer of a Ferro-Nanofluid in a Magnetic Field

1
Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, State College, PA 16803, USA
2
School of Marine Science and Technology, Northwestern Polytechnical University, Xi’an 710072, China
3
Department of Energy, U. S. National Energy Technology Laboratory (NETL), Pittsburgh, PA 15236, USA
4
Department of Biomedical Engineering and Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA
*
Author to whom correspondence should be addressed.
Received: 8 June 2017 / Revised: 5 July 2017 / Accepted: 18 July 2017 / Published: 22 July 2017
(This article belongs to the Section Energy Fundamentals and Conversion)
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Abstract

In this paper, we study the effects of the Lorentz force and the induced anisotropic thermal conductivity due to a magnetic field on the flow and the heat transfer of a ferro-nanofluid. The ferro-nanofluid is modeled as a single-phase fluid, where the viscosity depends on the concentration of nanoparticles; the thermal conductivity shows anisotropy due to the presence of the nanoparticles and the external magnetic field. The anisotropic thermal conductivity tensor, which depends on the angle of the applied magnetic field, is suggested considering the principle of material frame indifference according to Continuum Mechanics. We study two benchmark problems: the heat conduction between two concentric cylinders as well as the unsteady flow and heat transfer in a rectangular channel with three heated inner cylinders. The governing equations are made dimensionless, and the flow and the heat transfer characteristics of the ferro-nanofluid with different angles of the magnetic field, Hartmann number, Reynolds number and nanoparticles concentration are investigated systematically. The results indicate that the temperature field is strongly influenced by the anisotropic behavior of the nanofluids. In addition, the magnetic field may enhance or deteriorate the heat transfer performance (i.e., the time-spatially averaged Nusselt number) in the rectangular channel depending on the situations. View Full-Text
Keywords: nanofluids; anisotropic thermal conductivity; Lorentz force; magnetic nanofluids (MNFs); heat transfer nanofluids; anisotropic thermal conductivity; Lorentz force; magnetic nanofluids (MNFs); heat transfer
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Li, Y.; Yan, H.; Massoudi, M.; Wu, W.-T. Effects of Anisotropic Thermal Conductivity and Lorentz Force on the Flow and Heat Transfer of a Ferro-Nanofluid in a Magnetic Field. Energies 2017, 10, 1065.

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