Manipulating Boiling Bubble Dynamics on Under‐Liquid Superaerophobic Silicon Surfaces for High‐Performance Phase‐Change Cooling

Abstract

Abstract Enhancing critical heat flux (CHF) and heat transfer coefficient (HTC) by promoting the nucleation, growth, and departure of boiling bubbles has drawn significant attention owing to its wide applications. However, in‐depth understanding and comprehensive manipulation of under‐liquid bubble dynamics from in situ microscale perspectives remain challenging. Herein, in situ observations and analyses of the microsized boiling bubbles of ultra‐low surface tension fluorinated liquids (FLs) are conducted on the superaerophobic silicon surfaces with crisscross microchannels and selective nanowires. It is revealed that deep microchannels yet short nanowires enable ultrafast liquid spreading (<549.6 ms) and ultralow bubble adhesion (≈1.1 µN), while an appropriate spacing (240–600 µm) between microchannels minimizes the bubble departure time (<20.6 ms) due to timely coalescence. By verifying the above bubble dynamics principles through the collaborative enhancement of CHF and HTC, an optimized structure (microchannel depth ≈52.9 µm, microchannel spacing ≈362.9 µm, nanowire length ≈0 nm) is obtained and further implemented onto the exposed Si surface of a commercial CPU chip. Cooled by phase‐change of FLs, the average temperature of CPU maintains ≈64.9 °C even under extreme power loads (≈130 W), far below than those in conventional air‐cooling and water‐cooling operations.