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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

Bejan number for different φ values: 1, 4 and 6%.
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Figure 9: Bejan number for different φ values: 1, 4 and 6%.

Mentions: The behaviour of Bejan number is reported in Figure 9. It is observed that Be decreases as Re and φ increase, showing that (Sgen)F is increasing. For φ = 4% and Re = 1.0 × 105 and for φ = 6% and Re = 8.0 × 104, Be is about 0.5. This means that entropy generation, due to heat transfer and friction losses, have the same weight. Up to Re = 2 × 104, Be is equal to 1 for all concentrations, showing that in all considered cases, the entropy generation is due to thermal irreversibility. For Re > 2 × 104, Be value starts to decrease, but with different slopes according to particles' concentration. Particularly, at the higher concentration, there is higher slope, because the friction losses, due to the increase of Re and viscosity, become more relevant.


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)

Bejan number for different φ values: 1, 4 and 6%.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 9: Bejan number for different φ values: 1, 4 and 6%.
Mentions: The behaviour of Bejan number is reported in Figure 9. It is observed that Be decreases as Re and φ increase, showing that (Sgen)F is increasing. For φ = 4% and Re = 1.0 × 105 and for φ = 6% and Re = 8.0 × 104, Be is about 0.5. This means that entropy generation, due to heat transfer and friction losses, have the same weight. Up to Re = 2 × 104, Be is equal to 1 for all concentrations, showing that in all considered cases, the entropy generation is due to thermal irreversibility. For Re > 2 × 104, Be value starts to decrease, but with different slopes according to particles' concentration. Particularly, at the higher concentration, there is higher slope, because the friction losses, due to the increase of Re and viscosity, become more relevant.

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