Natural convection heat transfer analysis of copper-alumina/water hybrid nanofluid in a U-shaped enclosure / Muhammad Solleh Asmadi
Heat transfer by natural convection inside a U-shaped enclosure is investigated while considering the working fluid as hybrid nanofluid. Copper (Cu) and alumina (Al2O3) nanoparticles are suspended in pure water to form hybrid nanofluids. Various aspects of physical properties are varied to see th...
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| Format: | Thesis |
| Published: |
2022
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| Subjects: | |
| Online Access: | http://studentsrepo.um.edu.my/14744/1/Muhammad_Solleh.pdf http://studentsrepo.um.edu.my/14744/2/Muhammad_Solleh.pdf http://studentsrepo.um.edu.my/14744/ |
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| Summary: | Heat transfer by natural convection inside a U-shaped enclosure is investigated while
considering the working fluid as hybrid nanofluid. Copper (Cu) and alumina (Al2O3)
nanoparticles are suspended in pure water to form hybrid nanofluids. Various aspects of
physical properties are varied to see the effect of each factor on the overall heat transfer
rate. The nanoparticle shape, the enclosure inclination angle, the enclosure obliqueness
angle, the length and position of the heating element, the thermal profiles at the hot
wall, the waviness of the walls, and the cold baffle are thoroughly varied to find the most
suitable combinations of parameters for certain applications. The governing equations
are transformed to their dimensionless form using a set of dimensionless variables to
ensure generality. The Galerkin weighted residual finite element method is employed to
solve the problem with the entire domain being discretized to a finite number of threenode
triangular elements. A damped Newton-Raphson iteration algorithm is used as a
convergence condition. Several grid dependency tests are done to ensure the results obtained
through the numerical procedure are not affected regardless of the grid configurations.
Numerical comparisons with the previously published numerical and experimental data
are conducted to ascertain the validity and reliability of the numerical algorithm and
formulations. The heat transfer rate within the enclosure is measured by using the local
and average Nusselt numbers. A comparison of the heat transfer rate between Cu/water
and Al2O3/water with Cu-Al2O3/water hybrid nanofluid is done to examine the advantages
of using hybrid nanofluid compared to mono nanofluids. The nanoparticle volume fraction and its ratios, the Rayleigh number, the cold rib dimension, the cold rib position, the hot
thermal profiles, the heater element length and position, the enclosure inclination angle,
the enclosure obliqueness angle, the adiabatic and hot waviness, and the cold baffle length
are varied and investigated extensively by examining the streamlines, the isotherms, the
vorticity, the average Nusselt number, the local Nusselt number across the hot wall and cold
rib, the velocity profile, the absolute maximum stream function value and the maximum
vorticity for several combinations of parameters. It is observed that the heat transfer rate
increases as the Rayleigh number increases and the benefit of using hybrid nanofluid
in terms of thermal performance exceeds those of pure water and mono nanofluids in
the thermal dissipation rate. A symmetric enclosure configuration will be preferable for
applications where a high heat transfer rate is needed.
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