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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

Total entropy generation for (a) φ = 1%, (b) φ = 4%, (c) φ = 6%.
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Figure 8: Total entropy generation for (a) φ = 1%, (b) φ = 4%, (c) φ = 6%.

Mentions: According to Equation 27, the optimal Reynolds number for each concentration is calculated, as reported in Table 1. It is noted that Reopt value decreases as the φ value increases. This is also shown in Figure 8, where the numerical calculation of total entropy generation as a function of Re is reported for each concentration value. The analytical results of Equation 27 are in very good agreement with the numerical results (Figure 8); in fact, the minimum points of the curves correspond to the Reynolds values reported in Table 1. This result can also be considered an indirect proof of the agreement between results proposed by Pak and Cho [19] and the mixture model employed in the present article. In Figure 8, it is noted that the optimal value of Reynolds number decreases as the concentration increases. This happens because the increase of the viscosity becomes more and more important, overcoming the beneficial effect that the particles have on the heat transfer and, consequently, on (Sgen)T.


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)

Total entropy generation 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 8: Total entropy generation for (a) φ = 1%, (b) φ = 4%, (c) φ = 6%.
Mentions: According to Equation 27, the optimal Reynolds number for each concentration is calculated, as reported in Table 1. It is noted that Reopt value decreases as the φ value increases. This is also shown in Figure 8, where the numerical calculation of total entropy generation as a function of Re is reported for each concentration value. The analytical results of Equation 27 are in very good agreement with the numerical results (Figure 8); in fact, the minimum points of the curves correspond to the Reynolds values reported in Table 1. This result can also be considered an indirect proof of the agreement between results proposed by Pak and Cho [19] and the mixture model employed in the present article. In Figure 8, it is noted that the optimal value of Reynolds number decreases as the concentration increases. This happens because the increase of the viscosity becomes more and more important, overcoming the beneficial effect that the particles have on the heat transfer and, consequently, on (Sgen)T.

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