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

Pool boiling offers exceptional heat transfer performance, making it crucial for advanced thermal management. However, simultaneously optimizing both critical heat flux (CHF) and heat transfer coefficient (HTC) is challenging due to the inherent trade-off between promoting bubble nucleation and mitigating detrimental bubble coalescence. This study presents a micro/nano-hierarchical surface architecture designed to overcome this limitation. Fabricated via laser machining and chemical vapor deposition, the architecture comprises an array of micro pits (MPs) decorated with Co-catalyzed carbon nanotubes (CoCNTs). Computational fluid dynamics (CFD) simulations demonstrate that the MP array enhances HTC by increasing the density of nucleation sites and reducing the bubble departure diameter. Simultaneously, the CoCNTs within the MPs enhance interfacial heat transfer and promote capillary-driven liquid replenishment to the heating surface, effectively mitigating dry-out and significantly improving CHF. The synergistic effects of these micro/nanofeatures yield remarkable performance enhancements on Cu substrates, with the HTC and CHF increasing by 211.5% and 125.2%, respectively, compared to a bare Cu surface. This hierarchical surface design offers a promising strategy for developing high-performance boiling heat transfer surfaces for next-generation thermal management applications.