Acoustofluidics-assisted strategy of zinc oxide nanoarrays for enhancement of phase-change chip cooling

Enhancing flow boiling in microchannel via surface modification is crucial for addressing the energy consumption challenges posed by high-power compact electronic devices. However, improving boiling heat transfer performance with well-defined nanostructured surfaces in a limited space remains a challenge. Herein, we present a simple and straightforward acoustofluidics strategy for stable, controllable, and efficient fabricates of functional Zinc oxide (ZnO) nanoarray silicon chip surface with excellent phase change cooling performance. The intentionally designed flower-like sharp-edge structure integrated acoustic has been experimentally and numerically verified for its enhanced mass transfer mixing. The resulting ZnO nanoarray-coated chip with customizable lengths, densities, and morphology is implemented by simple reactor parameter adjustment. Excellent boiling heat transfer performance is obtained on this surface, giving priority to nucleation (superheat≈ 4 °C), low energy consumption (≤3.2 kPa) and simultaneously enhancing the critical heat flux (CHF) and heat-transfer coefficient (HTC) by up to 70.8 % and 107.5 %, respectively, compared with a smooth chip surface. In situ observation and analysis of the wicking of the nanoarray and nucleation, growth, and departure of the bubbles reflect that ZnO nanoarray promotes the phase change heat exchange process by the large number of nucleation sites and ultrafast liquid re-wetting. These findings not only provide important guidelines for the precise control and rational design of functional nanomaterials, but also provide new insights for embedded cooling and significant energy savings on power devices.