Thermophysical Properties Of CNF-Based Nanocoolant As A Heat Transfer Media

Zainal Abidin, Syazwani (2019) Thermophysical Properties Of CNF-Based Nanocoolant As A Heat Transfer Media. Masters thesis, Universiti Teknikal Malaysia Melaka.

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Abstract

High heat flux removal is one of the major challenges in designing for the future electronic devices. The trend to address these high heat fluxes is to introduce microchannel arrays directly in the heat generating by the electronic component. Commonly, water is suggested to be used as a single-phase coolant in combination with the microchannel heat sinks for cooling of electronics applications. However, one of the major problems faced by the existing coolants is the limited amount of heat that can be absorbed by the fluids. An innovative way to overcome this limitation is by utilizing a nanocoolant as the heat transfer medium in a cooling application. This research was aimed at formulating an efficient nanocoolant from PR-24 HHT carbon nanofibers (CNF) in a base fluid consisting of deionized water (DI) and ethylene glycol (EG). The dispersion of nanofibers was enhanced by the presence of polyvinylpyrrolidone (PVP) as the stabilizing agent through two-step preparation process. The experiment was conducted by setting the variable weight percentage of CNF from 0.1wt% to 1.0wt%, with the base fluid ratio range from 100:0 (DI:EG) to 0:100 (DI:EG). The characterization testing was performed to study the surface species of the nanofiber using nitrogen gas adsorption technique, fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM). The detailed study of the thermophysical properties such as thermal conductivity, viscosity, and specific heat capacity of stable CNF-based nanocoolant was also been investigated at three different temperatures (6°C, 25°C and 40°C). The maximum thermal conductivity enhancement of 29.95% was noticed for the nanocoolant with 0.6wt% at 0:100 (DI:EG). The rheological analysis showed that when the temperature increases, the viscosity diminishes. Whereas, due to a lower specific heat of the CNF, the specific heat of the nanocoolant decreased in proportion with the CNF concentration. Experimental investigations into the forced convective heat transfer performance of the CNF-based nanocoolant in a laminar flow through a mini heat transfer test rig showed that the presence of nanoparticles enhanced the heat transfer coefficient as opposed to the original base fluid. The highest heat transfer coefficient was reported with 30:70 (DI:EG) by the 0.7wt% nanocoolant at 40°C with the value of 265.28 x 103 W/m2.K. The enhancement of the heat transfer coefficient was due to the higher thermal conductivity value. The Nusselt number was also calculated and presented in this research. Overall, this study shows that the CNF-based nanocoolant has a huge potential to replace existing coolants in electronic cooling applications. Thus, in order to commercialize nanocoolant in practice, more fundamental studies are needed to understand the crucial parameters that affect their thermal characteristics.

Item Type:	Thesis (Masters)
Uncontrolled Keywords:	Heat, Transmission, Thermophysical Properties, CNF, Nanocoolant, Heat Transfer Media
Subjects:	T Technology > TJ Mechanical engineering and machinery
Divisions:	Library > Tesis > FKM
Depositing User:	F Haslinda Harun
Date Deposited:	05 Nov 2020 08:49
Last Modified:	05 Oct 2021 12:24
URI:	http://eprints.utem.edu.my/id/eprint/24662
Statistic Details:	View Download Statistic

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