Multilevel synergistic enhanced trapezoidal open microchannel heat sink for thermal management of electronic devices

The microchannel heat sinks exhibit significant potential in the thermal management of electronic devices. Compared to traditional enclosed microchannel heat sinks, open microchannel heat sinks offer advantages such as enhanced heat transfer capacity, reduced pressure drop, and improved flow stability. However, research on flow boiling enhancement in open microchannels remains relatively limited. In this study, a multilevel synergistic enhancement strategy for flow boiling in open microchannels has been proposed, incorporating a trapezoidal cover plate coupled with laser-processed micropillar structures (TOMC). A microchannel heat sink was fabricated with a surface featuring visible micropillars, microspheres, and microcavities, with sizes ranging from 1 μm to 50 μm. The flow boiling characteristics of three open microchannel heat sinks, COM, TOM, and TOMC, were tested at different subcooling degrees and mass fluxes using HFE-7100. Compared with the other two configurations, the critical heat fluxes (CHF) of the TOMC heat sink were substantially increased by 35.9% to 170.6%, and the wall temperatures were decreased by 17.5 K. The average heat transfer coefficients (HTC) of the TOMC heat sink were increased by 66.1% to 122.0%. The laser-processed micropillar configuration provided effective nucleation sites and enhances capillary wicking capability, thereby maintaining wall wettability. The trapezoidal cover plate increased downstream flow velocity, accelerating bubble detachment and phase separation processes. Visualization results indicate that the multilevel synergistic enhancement of the TOMC heat sink, which sustained Type-I stratified flow over a broader range of heat fluxes, was critical to preventing heat transfer deterioration. Furthermore, by employing various comprehensive performance evaluation methods, the TOMC heat sink achieved outstanding overall performance, with a COP exceeding 20000. This work integrates multiple heat transfer enhancement techniques, offering new insights for efficient thermal management applications in electronic devices.