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ISSN Online: 2379-1748

ISBN Flash Drive: 978-1-56700-472-4

ISBN Online: 978-1-56700-471-7

3rd Thermal and Fluids Engineering Conference (TFEC)
March, 4–7, 2018, Fort Lauderdale, FL, USA

POOL BOILING OF SATURATED FC-72 USING SPHERICAL HOLLOW STRUCTURES FABRICATED BY SELECTIVE LASER MELTING

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DOI: 10.1615/TFEC2018.mph.021579

Resumo

Heat dissipation has become an increasing challenge for electronic devices due to the higher heat flux generated. Immersion cooling through nucleate pool boiling in a dielectric fluid has shown potential to maintain low surface temperatures of electronic chips for high heat flux applications. The upper limit of pool boiling is typically the Critical Heat Flux (CHF) condition where the formation of a vapor film at the heated surface causes large thermal resistance and a corresponding increase in surface temperature. In this study, spherical hollow structures were employed to enhance the nucleate pool boiling heat transfer coefficient and delay the CHF using saturated dielectric fluid FC-72 as the working fluid. The hollow structures were fabricated using the Selective Laser Melting (SLM) technique, which is a type of additive manufacturing technology. In SLM, a high-power laser is used to melt metallic powder layer by layer to form a three-dimensional substrate. Three hollow structures with different porosities of 18%, 35% and 50% were fabricated. The study showed that a maximum of 161% enhancement in heat transfer coefficient was obtained for these structures as compared to that of a plain surface. Also, the CHF was delayed by 347%. The enhancement can be attributed to the increased nucleation site density and capillary-assisted suction. Visualization studies also show that the hollow structures allow sustained liquid replenishment which delay hydrodynamic choking and CHF significantly.