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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

Entropy generation due to heat transfer irreversibility and friction losses for (a) φ = 1%, (b) φ = 4%, (c) φ = 6%.
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Figure 7: Entropy generation due to heat transfer irreversibility and friction losses for (a) φ = 1%, (b) φ = 4%, (c) φ = 6%.

Mentions: Entropy generation due to heat transfer and friction losses is reported for each concentration, as a function of Reynolds number in Figure 7, for φ = 1%, Figure 7a, φ = 4%, Figure 7b, and φ = 6%, Figure 7c. It is possible to observe that as Re value increases, there is a reduction of (Sgen)T, because there is a decrease in the difference between wall and bulk average temperatures, which causes a decrease in the entropy generation. On the contrary, as Re increases, there is an increment of (Sgen)F, because of the higher values of velocity gradient, which causes an increase of the wall shear stress, and, consequently, of the friction losses.


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)

Entropy generation due to heat transfer irreversibility and friction losses for (a) φ = 1%, (b) φ = 4%, (c) φ = 6%.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 7: Entropy generation due to heat transfer irreversibility and friction losses for (a) φ = 1%, (b) φ = 4%, (c) φ = 6%.
Mentions: Entropy generation due to heat transfer and friction losses is reported for each concentration, as a function of Reynolds number in Figure 7, for φ = 1%, Figure 7a, φ = 4%, Figure 7b, and φ = 6%, Figure 7c. It is possible to observe that as Re value increases, there is a reduction of (Sgen)T, because there is a decrease in the difference between wall and bulk average temperatures, which causes a decrease in the entropy generation. On the contrary, as Re increases, there is an increment of (Sgen)F, because of the higher values of velocity gradient, which causes an increase of the wall shear stress, and, consequently, of the friction losses.

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