Free convection enhancement in an annulus between horizontal confocal elliptical cylinders using hybrid nanofluids |
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Authors: | Tahar Tayebi |
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Affiliation: | 1. Energy Physics Laboratory, Department of Physics, Faculty of Science, Mentouri Brothers Constantine1 University, Constantine, Algeria;2. Faculty of Sciences and Technology, Mohamed El Bachir El Ibrahimi University, Bordj Bou Arreridj, El-Anasser, Algeria |
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Abstract: | ABSTRACTIn the present paper, natural convection in an annulus between two confocal elliptic cylinders filled with a Cu-Al2O3/water hybrid nanofluid is investigated numerically. The inner cylinder is heated at a constant surface temperature while the outer wall is isothermally cooled. The basic equations are formulated in elliptic coordinates and developed in terms of the vorticity-stream function formulation using the dimensionless form for 2D, laminar and incompressible flow under steady-state condition. The governing equations are discretized using the finite volume method and solved by an in-house FORTRAN code. Numerical simulations are performed for various volume fractions of nanoparticles (0?≤???≤?0.12) and Rayleigh numbers (103?≤?Ra?≤?3?×?105). The eccentricity of the inner and outer ellipses and the angle of orientation are fixed at e1?=?0.9, e2?=?0.6 and γ?=?0° respectively. It is found that employing a Cu-Al2O3/water hybrid nanofluid is more efficient in heat transfer rate compared to the similar Al2O3/water nanofluid. |
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