Two-phase boiling in advanced microchannel heat sinks offers an efficient and attractive solution for heat dissipation of high-heat-flux devices. In this study, a type of reentrant copper microchannels was developed for heat sink cooling systems. It consisted of 14 parallel Ω-shaped reentrant copper microchannels with a hydraulic diameter of 781μm. Two-phase pressure drop characteristics were comprehensively accessed via flow boiling tests. Both deionized water and ethanol tests were conducted at inlet subcooling of 10°C and 40°C, mass fluxes of 125–300kg/m2·s, and a wide range of heat fluxes and vapor qualities. The effects of heat flux, mass flux, inlet subcoolings and coolants on the two-phase pressure drop were systematically explored. The results show that the two-phase pressure drop of reentrant copper microchannels generally increased with increasing heat fluxes and vapor qualities. The role of mass flux and inlet temperatures was dependent on the test coolant. The water tests presented smaller pressure drop than the ethanol ones. These results provide critical experimental information for the development of microchannel heat sink cooling systems, and are of considerable practical relevance.

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