The effect of nanofluids flow on mixed convection heat transfer over microscale backward-facing step

Kherbeet, A.Sh.; Mohammed, Hussein A.; Salman, B.H.

doi:10.1016/j.ijheatmasstransfer.2012.05.084

Cited by 78 publications

(27 citation statements)

References 52 publications

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“…This is because inside the recirculation zone the nanofluid needs to have lower density and thermal conductivity. This result was also obtained by Kherbeet et al [31,32], In this study, the effect of the nanoparticle volume fraction 0 in the range of 1^1% on the heat transfer characteristics is studied. Figure 6(b) shows the effect of different nanoparticle volume frac tions on the Nusselt number for constant nanoparticle diameters (a) dp = 25 nm at Re = 300 and qw = 500 W/m2.…”

Section: Resultssupporting

confidence: 79%

Assisting and Opposing Combined Convective Heat Transfer and Nanofluids Flows Over a Vertical Forward Facing Step

Mohammed

Hussein

2014

Journal of Nanotechnology in Engineering and Medicine

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Numerical simulations of two-dimensional (2D) laminar mixed convection heat transfer and nanofluids flows over forward facing step (FFS) in a vertical channel are numerically carried out. The continuity, momentum, and energy equations were solved by means of a finite volume method (FVM). The wall downstream of the step was maintained at a uni form wall heat flux, while the straight wall that forms the other side of the channel was maintained at constant temperature equivalent to the inlet fluid temperature. The upstream walls for the FFS were considered as adiabatic surfaces. The buoyancy assist ing and buoyancy opposing flow conditions are investigated. Four different types of nanoparticles, Al20 3, CuO, Si02, and ZnO with different volumes' fractions in the range of 1-4% and different nanoparticle diameters in the range o f25-80 nm, are dispersed in the base fluid (water) are used. In this study, several parameters, such as different Rey nolds numbers in the range of 100 < Re < 900, and different heat fluxes in the range of 500

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Section: Resultssupporting

confidence: 79%

Assisting and Opposing Combined Convective Heat Transfer and Nanofluids Flows Over a Vertical Forward Facing Step

Mohammed

Hussein

2014

Journal of Nanotechnology in Engineering and Medicine

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“…He found that, in the circulation areas, the use of comparatively lower thermal conductive TiO 2 nanoparticles, the Nusselt number can still be improved. Kherbeet et al [18] investigated the laminar nanofluid-flow in a micro-scale backward-facing step and observed that, with the decreasing of nanoparticles diameter, Nusselt number enhances significantly.…”

Section: Introductionmentioning

confidence: 99%

Effect of flow separation of TiO2 nanofluid on heat transfer in the annular space of two concentric cylinders

et al. 2020

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In the wake of energy crises, the researchers are encouraged to explore new ways of enhancement in the thermal performance of heat exchanging equipment. In the current research, the SST k-ω model and finite volume method were employed to augment heat transfer into the separation flow of TiO 2 nanofluid in the annular space of two concentric cylinders. In the present investigation TiO 2 nanoparticles of volume fractions, 0.5%-2% at Reynolds number range of 10000-40000, and contraction ratios from 1 to 2 were considered at constant heat flux boundary condition. Simulation results reveal that the highest enhancement in the heat transfer coefficient is corresponding to the annular pipe with a contraction ratio of 2 due to the generated re-circulation flow zone that begins after the separation point on the wall. Further, the surface heat transfer coefficient enhances with the increase of nanoparticles volume fraction and Reynolds number. The velocity distribution profile before and after the steps reveals that increasing the height of the step and Reynolds number, re-circulation regions also increases. Numerical results indicate that the highest pressure drop occurs at the Re = 40000 and contraction ratio of 2.

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“…Their results, obtained in forced convection, show that nanoparticles with high thermal conductivity have more enhancement on the value of Nusselt number outside the recirculation zones. The effect of nanofluids flow on a mixed convection heat transfer over a 2D horizontal micro scale backward-facing step placed in a duct has been conducted numerically for different nanoparticles (Al 2 O 3 , CuO, SiO 2 and ZnO), whose, results show that the Nusselt number increases with the increase of the volume fraction and Reynolds number [11]. The compactness of new thermal systems leads the importance of finding effective means for enhancing heat transfer.…”

Section: Introductionmentioning

confidence: 99%

Heat Transfer Enhancement in a Backward-Facing Step with Heated Obstacle Using Nanofluid

Bouazizi¹

2018

Int. J. Automot. Mech. Eng.

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A numerical investigation was conducted to analyze the effect of the presence of a square obstacle placed behind the first primary recirculation zone on the flow field and heat transfer over a backward-facing step using copper-water nanofluid. Computations were performed over a range of Richardson number from 0 to 2.85 and volume fraction of nanoparticles φ from 0 to 15% at a fixed Reynolds number Re = 450 and Prandtl number Pr = 6.2. A discussion about the buoyancy effect on the heat transfer exchanged between the horizontal walls of the channel as well as on the heat flux transferred from the obstacle to the flow for different φ. Results show that, the presence of heated square obstacle is effective in augmenting the heat transfer. In fact, in presence of the square obstacle, enhancements in the maximum values of the Nusselt number of 194% and 153% are obtained at the lower and the upper walls of the channel, respectively. Furthermore, the heat transfer reaches its maximum at the emplacement of the square cylinder. On the other hand, results show a marked improvement in heat transfer compared to the base fluid. This improvement is more pronounced for higher and φ. Finally, the effect of the buoyancy forces is found less important on the heat transfer enhancements when Ri increases. This can be explained by the thermophoresis forces effect near the hot walls of the obstacle.

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The effect of nanofluids flow on mixed convection heat transfer over microscale backward-facing step

Cited by 78 publications

References 52 publications

Assisting and Opposing Combined Convective Heat Transfer and Nanofluids Flows Over a Vertical Forward Facing Step

Assisting and Opposing Combined Convective Heat Transfer and Nanofluids Flows Over a Vertical Forward Facing Step

Effect of flow separation of TiO2 nanofluid on heat transfer in the annular space of two concentric cylinders

Heat Transfer Enhancement in a Backward-Facing Step with Heated Obstacle Using Nanofluid

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