Heat transfer and turbulent nanofluid flow investigation over microscale backward-facing step
Flow separation and re-connection play important roles in many different fields. The continued increase in functionality and compactness in these fields and devices such as the microchannel, micro heat-exchangers. In the present study, experimental and numerical simulation using computational...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
2021
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/97867/1/FK%202021%2047%20UPMIR.pdf |
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| Summary: | Flow separation and re-connection play important roles in many different fields.
The continued increase in functionality and compactness in these fields and devices
such as the microchannel, micro heat-exchangers. In the present study,
experimental and numerical simulation using computational fluid dynamics (CFD)
is applied to study the steady-state convective turbulent nanofluids and hybrid /water. However, the nanofluid of Ga2O3/water enhances the heat transfer rate in
comparison with CuO/water nanofluid. Overall, the results showed promising
outcomes of utilizing nanoparticles in the separation flow to enhance the heat
transfer to the industry that relies on the heat transfer as the main goal to achieve
such as heat exchanger.
nanofluids flow over two-dimensional (2D) microscale backward-facing step
(MBFS) placed in a channel. In this research, the wall downstream of the channel
was maintained at a uniform heat flux, while the straight wall that forms the other
side of the duct was maintained at a constant temperature equal to inlet fluid
temperature. The upstream wall and the step wall were considered adiabatic
surfaces. The expected valid trend of step height (S) length scale is considered in
the range of 200 ≤ S ≤ 500 μm for the numerical study. The Reynolds number (Re)
range in the study of 5,000 ≤ Re ≤ 10,000. All the other walls including the step
were considered adiabatic. The step height was S = 500 μm in the experimental
study. Different types of nanoparticles such as CuO and Ga2O3 with a volume
fraction ( of 1%≤ ≤4% are dispersed in the water. Moreover, hybrid
nanoparticles of CuO and Ga2O3 with 4% volume fraction have been applied in
this study. To ensure the purity of CuO and Ga2O3 nanoparticles SEM, particle
size distribution, and XRD characterizations have been applied. The outcomes
reveal that the gradients in the Nusselt number (Nu) inside the recirculation region
increase by increasing the S. It also appears that increasing the S decreases the
pressure-drop and Re. Heat transfer rate enhances with an increase in any of the
parameters of volume fraction ( and Reynolds number (Re). Also, the friction
factor has a significant consequence on the rate of heat transfer and characteristics
of the flow at a constant Re. Besides, the outcomes revealed the friction factor
increased by increasing the volume fraction. The hybrid nanofluids of Ga2O3-CuO
/water have a higher value of Nu in comparison with Ga2O3/water and CuO. |
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