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Investigation of heat transfer in a microchannel heat sink using water and Al2O3 nanofluids

Razali, Azlizul Aizat (2017) Investigation of heat transfer in a microchannel heat sink using water and Al2O3 nanofluids. Masters thesis, Universiti Tun Hussein Onn Malaysia.


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Microchannel heat sink is a small device that creates an innovative cooling technology to remove large amount of heat from small area. The dimensions ranging are from 10 μm to 1000 μm and commonly, it has been used for electronic cooling. However, there was limit confined by manufacturing technology and on conduction inside solid material to created small dimension of channel. Therefore present study investigates heat transfer in a microchannel using water and Al2O3 nanofluids as working fluids in a square microchannel. The investigation has been carried out by experimental and CFD simulation. The microchannel was designed and fabricated in square cross section with 0.5 mm height and width with length of 28.0 mm whereas made from copper. During the experiment, a constant heat input of 325 W was set up at bottom of the heat sink. The combination of microchannel and nanofluids has provided both highly conducting fluids and large heat transfer area. This investigation found that heat transfer was achieved by using 2.5 wt. % Al2O3 nanofluids. The CFD simulation was performed in three dimensional and solving the conjugate heat transfer problem according to the experiment. In addition, present heat transfer performance was simulating on 5.0 wt. % concentration and found that it is yields the same result as use water. In order to understand more on the heat transfer performance in microchannel, this study has analyzed Nusselt number between the presented experimental and literature conventional correlations. It was clearly shown that, the experimental result have similarity pattern to the conventional correlations proposed by Boelter and Zerradi. After 10 hours of application of Al2O3 nanofluids, it was confirmed by XRD method that the heating process in the microchannel has not changed the structure of Al2O3 nanofluids. According to the XRD patterns show that the diffraction peaks are sharper after increase the temperature. Besides that, the morphological study found the heating process inside the microchannel has increased the grain size of Al2O3 nanofluids. Therefore, this investigation concluded that Al2O3 nanofluids improve the performances of heat transfer in the microchannel heat sink. tTe structure of Al2O3 nanofluids have no changed after 10 hours in the heating side but the grain size increased because of the particles started to agglomerate.

Item Type: Thesis (Masters)
Subjects: T Technology > TJ Mechanical engineering and machinery > TJ836-935 Hydraulic machinery
Depositing User: Mr. Mohammad Shaifulrip Ithnin
Date Deposited: 27 Mar 2018 03:59
Last Modified: 27 Mar 2018 03:59
URI: http://eprints.uthm.edu.my/id/eprint/9894
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