Micro Bubble Blanket Coated Nano-Ridge Surfaces for Robust and Efficient Thermal Management

To achieve robust and high-efficient thermal management at micro scale, this study focuses on interplay of a micro bubble blanket and lifting large bubbles on locally heated surfaces with nano-ridge structures. The micro bubble blanket covers the surface dynamically after heat fluxes exceed a criterion where heat transfer coefficients exhibit constant values, highlighting the robust and predictable two-phase heat transfer. By quantitative investigations of diameters as well as lifting speed of large bubbles, it ensures that convective boiling heat transfer mechanism dominates without forced convection, accounting for constant heat transfer coefficient at high-heat-flux regions. Force analyses are adopted to investigate the individual micro bubbles that form the bubble blanket, which is pinned downside to nano-ridge surfaces by free energy while pulled upside by merging effect of buoyancy-driven large bubbles. The presence of the bubble blanket facilitates the removal of large bubbles by modifying the surface tension distribution, sustaining safe boiling heat transfer across a broad range of heat fluxes. This approach achieves a convective boiling mechanism without the need for power equipment, opening a new paradigm in microscale heat removal that is both robust and energy-efficient.