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Enhancement of heat transfer and entropy generation analysis of nanofluids turbulent convection flow in square section tubes.

Bianco V, Nardini S, Manca O - Nanoscale Res Lett (2011)

Bottom Line: In this article, developing turbulent forced convection flow of a water-Al2O3 nanofluid in a square tube, subjected to constant and uniform wall heat flux, is numerically investigated.A simple analytical procedure is proposed to evaluate the entropy generation and its results are compared with the numerical calculations, showing a very good agreement.A comparison of the resulting Nusselt numbers with experimental correlations available in literature is accomplished.To minimize entropy generation, the optimal Reynolds number is determined.

View Article: PubMed Central - HTML - PubMed

Affiliation: Dipartimento di Ingegneria Aerospaziale e Meccanica, Seconda Università degli Studi di Napoli, Via Roma 29, Aversa, CE 81031, Italy. oronzio.manca@unina2.it.

ABSTRACT
In this article, developing turbulent forced convection flow of a water-Al2O3 nanofluid in a square tube, subjected to constant and uniform wall heat flux, is numerically investigated. The mixture model is employed to simulate the nanofluid flow and the investigation is accomplished for particles size equal to 38 nm.An entropy generation analysis is also proposed in order to find the optimal working condition for the given geometry under given boundary conditions. A simple analytical procedure is proposed to evaluate the entropy generation and its results are compared with the numerical calculations, showing a very good agreement.A comparison of the resulting Nusselt numbers with experimental correlations available in literature is accomplished. To minimize entropy generation, the optimal Reynolds number is determined.

No MeSH data available.


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Comparison of average Nusselt number of this study with correlations proposed by Gnielinski [41], Petukhov [42]and Nusselt [43].
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Figure 2: Comparison of average Nusselt number of this study with correlations proposed by Gnielinski [41], Petukhov [42]and Nusselt [43].

Mentions: Results showed that for the problem under consideration, the chosen non-uniform grid seems to be sufficient to guarantee the precision of numerical results and their independency with respect to the number of elements used. The considered grid has 25, 50 and 200 elements along the horizontal, vertical and axial directions, respectively, with heavily packed grid points close to the channel wall and at the entrance region, where the temperature and velocity gradients are significant [29]. The computational grid is validated using the correlations proposed by Gnielinski, as also suggested in [27], Petukhov and Nusselt [43-45] for pure water, as shown in Figure 2.


Enhancement of heat transfer and entropy generation analysis of nanofluids turbulent convection flow in square section tubes.

Bianco V, Nardini S, Manca O - Nanoscale Res Lett (2011)

Comparison of average Nusselt number of this study with correlations proposed by Gnielinski [41], Petukhov [42]and Nusselt [43].
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211314&req=5

Figure 2: Comparison of average Nusselt number of this study with correlations proposed by Gnielinski [41], Petukhov [42]and Nusselt [43].
Mentions: Results showed that for the problem under consideration, the chosen non-uniform grid seems to be sufficient to guarantee the precision of numerical results and their independency with respect to the number of elements used. The considered grid has 25, 50 and 200 elements along the horizontal, vertical and axial directions, respectively, with heavily packed grid points close to the channel wall and at the entrance region, where the temperature and velocity gradients are significant [29]. The computational grid is validated using the correlations proposed by Gnielinski, as also suggested in [27], Petukhov and Nusselt [43-45] for pure water, as shown in Figure 2.

Bottom Line: In this article, developing turbulent forced convection flow of a water-Al2O3 nanofluid in a square tube, subjected to constant and uniform wall heat flux, is numerically investigated.A simple analytical procedure is proposed to evaluate the entropy generation and its results are compared with the numerical calculations, showing a very good agreement.A comparison of the resulting Nusselt numbers with experimental correlations available in literature is accomplished.To minimize entropy generation, the optimal Reynolds number is determined.

View Article: PubMed Central - HTML - PubMed

Affiliation: Dipartimento di Ingegneria Aerospaziale e Meccanica, Seconda Università degli Studi di Napoli, Via Roma 29, Aversa, CE 81031, Italy. oronzio.manca@unina2.it.

ABSTRACT
In this article, developing turbulent forced convection flow of a water-Al2O3 nanofluid in a square tube, subjected to constant and uniform wall heat flux, is numerically investigated. The mixture model is employed to simulate the nanofluid flow and the investigation is accomplished for particles size equal to 38 nm.An entropy generation analysis is also proposed in order to find the optimal working condition for the given geometry under given boundary conditions. A simple analytical procedure is proposed to evaluate the entropy generation and its results are compared with the numerical calculations, showing a very good agreement.A comparison of the resulting Nusselt numbers with experimental correlations available in literature is accomplished. To minimize entropy generation, the optimal Reynolds number is determined.

No MeSH data available.


Related in: MedlinePlus