Synergistic Boiling Enhancement on Hierarchical Micro-Pit/Carbon Nanotube Surfaces

Area of Science:

• Thermal engineering
• Materials science
• Nanotechnology

Background:

• Pool boiling is vital for thermal management but faces challenges in optimizing heat transfer coefficient (HTC) and critical heat flux (CHF).
• A trade-off exists between bubble nucleation and coalescence, hindering simultaneous HTC and CHF enhancement.

Purpose of the Study:

• To design and fabricate a micro/nano-hierarchical surface architecture for improved pool boiling performance.
• To overcome the limitations in simultaneously optimizing HTC and CHF.

Main Methods:

• Fabrication using laser machining and chemical vapor deposition to create micro pits (MPs) decorated with Co-catalyzed carbon nanotubes (CoCNTs).
• Utilized computational fluid dynamics (CFD) simulations to analyze heat transfer mechanisms.
• Experimental evaluation on copper (Cu) substrates.

Main Results:

• The micro/nano-hierarchical surface demonstrated enhanced HTC due to increased nucleation sites and reduced bubble departure diameter.
• CoCNTs within MPs improved interfacial heat transfer and liquid replenishment, mitigating dry-out and enhancing CHF.
• Achieved a 211.5% increase in HTC and a 125.2% increase in CHF on Cu substrates compared to a bare surface.

Conclusions:

• The synergistic effect of micro and nano-features in the hierarchical surface design significantly boosts boiling heat transfer performance.
• This approach offers a promising strategy for developing high-performance heat transfer surfaces for advanced thermal management applications.