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Serpentine minichannel liquid-cooled heat sinks for electronics cooling applications

Al-Neama, Ahmed Fouad Mahmood (2018) Serpentine minichannel liquid-cooled heat sinks for electronics cooling applications. PhD thesis, University of Leeds.

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The increasing density of transistors in electronic components is leading to an inexorable rise in the heat dissipation that must be achieved in order to preserve reliability and performance. Hence, improving the thermal management of electronic devices is a crucial goal for future generations of electronic systems. Therefore, a complementary experimental and numerical investigation of single-phase water flow and heat transfer characteristics of the benefits of employing three different configurations of serpentine minichannel heat sink (MCHS) designs has been performed, to assess their suitability for the thermal management of electronic devices. These heat sinks are termed single (SPSMs), double (DPSMs) and triple path serpentine rectangular minichannels (TPSMs), and their performance is compared, both experimentally and numerically, with that of a design based on an array of straight rectangular minichannels (SRMs) in terms of pressure drop (ΔP), average Nusselt number (Nuavg) and total thermal resistance (Rth). The results showed that the serpentine channel bends are very influential in improving heat transfer by preventing both the hydrodynamic and thermal boundary layers from attaining a fully-developed state. The SPSM design provides the most effective heat transfer, followed by the DPSM and TPSM ones, both of which out-performed the SRM heat sink. The SPSM heat sink produced a 35% enhancement in Nuavg and a 19% reduction in Rth at a volumetric flow rate (Qin) of 0.5 l/min compared to the conventional SRM heat sink. These improvements in the heat transfer are, however, achieved at the expense of significantly larger ΔP. It was found that the incorporation of serpentine minichannels into heat sinks will significantly increase the heat-removal ability, but this must be balanced with the pressure drop requirement. Therefore, an experimental and numerical investigation of the benefit of introducing chevron fins has been carried out to examine the potential of decreasing pressure drop along with further thermal enhancement. This novel design is found to significantly reduce both the ΔP across the heat sink and the Rth by up to 60% and 10%, respectively, and to enhance the Nuavg by 15%, compared with the SPSM heat sink without chevron fins. Consequently, the design of the SPSM with and without chevron fins was then optimised in terms of the minichannel width (Wch) number of minichannels (Nch) and chevron oblique angle (θ). The optimisation process uses a 30 (without chevron fins) and 50 (with chevron fins) point Optimal Latin Hypercubes Design of Experiment, generated from a permutation genetic algorithm, and accurate metamodels built using a Moving Least Square (MLS) method. A Pareto front is then constructed to enable the compromises available between designs with a low pressure drop and those with low thermal resistance to be explored and appropriate design parameters to be chosen. These techniques have then been used to explore the feasibility of using serpentine MCHS and heat spreaders to cool GaN HEMTs

Item Type: Thesis (PhD)
Keywords: Serpentine minichannel heat sinks, Chevron fins, GaN HEMT devices, Optimisation, Multiobjective genetic algorithm
Academic Units: The University of Leeds > Faculty of Engineering (Leeds) > School of Mechanical Engineering (Leeds) > Institute of Engineering Thermofluids, Surfaces & Interfaces (iETSI) (Leeds)
Identification Number/EthosID: uk.bl.ethos.741197
Depositing User: Dr. Ahmed Fouad Mahmood AL-NEAMA
Date Deposited: 14 May 2018 15:06
Last Modified: 25 Jul 2018 09:57
URI: http://etheses.whiterose.ac.uk/id/eprint/20318

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