Numerical simulation of the capillary-driven evaporative heat transfer characteristics of hierarchical micro pore-channel composite evaporators

Abstract

Hierarchical evaporators have emerged as an important technology for high heat flux thermal management in modern electronics through capillary-driven evaporation mechanisms. Current implementations predominantly employ nano-scale structures that achieve exceptional heat transfer performance, yet their characteristic sub-micron dimensions impose severe permeability constraints, fundamentally limiting applicability to chip-scale systems (>10 mm²). To elucidate the thermal-flow coupling mechanisms in advanced fabrication-enabled hierarchical evaporators, this study conducts systematic numerical investigations addressing critical knowledge gaps in their microstructural design principles. A dual-scale computational framework is developed to resolve the coupled heat transfer and capillary flow dynamics, and to further analyze the combined influence of key geometric design parameters across microstructural features and system-level configurations. The maximum dry-out heat flux is achieved at an aspect ratio of nearly unity by balancing capillary and viscous effects. The optimized evaporator design demonstrates stable operation at 154.5 W/cm² with a heat transfer coefficient of 97.19 kW/(m²K), outperforming conventional micropillar-based systems while maintaining compatibility with industrial manufacturing standards. These findings establish essential design principles for next-generation phase-change thermal management devices that simultaneously address thermal performance, scalability, and production feasibility challenges.