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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.


Related in: MedlinePlus

Axial evolution of centreline velocity for φ = 4%.
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Figure 3: Axial evolution of centreline velocity for φ = 4%.

Mentions: The development of the axial velocity along the tube centreline for φ = 4% is shown in Figure 3 and the results suggest the existence of a fully developed region for z/D ≈ 40 for all the considered Reynolds numbers. Immediately after the tube inlet, the boundary layer growth pushes the fluid towards the centreline region, causing an increase of the centreline velocity. As the Reynolds number increases, the maximum value of axial velocity moves further downstream, because the increase of axial momentum transports the generated turbulence in the flow direction. After the maximum point, the velocity at the centreline decreases in order to respect the continuity equation, as also reported in [29].


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)

Axial evolution of centreline velocity for φ = 4%.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: Axial evolution of centreline velocity for φ = 4%.
Mentions: The development of the axial velocity along the tube centreline for φ = 4% is shown in Figure 3 and the results suggest the existence of a fully developed region for z/D ≈ 40 for all the considered Reynolds numbers. Immediately after the tube inlet, the boundary layer growth pushes the fluid towards the centreline region, causing an increase of the centreline velocity. As the Reynolds number increases, the maximum value of axial velocity moves further downstream, because the increase of axial momentum transports the generated turbulence in the flow direction. After the maximum point, the velocity at the centreline decreases in order to respect the continuity equation, as also reported in [29].

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