Unidirectional wicking-driven flow boiling on tilted pillar structures for high-power applications

Energy management issues of data center cooling systems have been aggravated because of the miniaturization of electronic components. The cooling systems consume considerable energy, requiring more electric power supplied by power plants to prevent system failure from overheating. Among cooling methods applied in industrial fields, two-phase immersion cooling is the most potential cooling method for resolving energy consumption issues with extraordinary heat transfer capacity. To further augment the overall heat transfer performance, we propose polymerized surfaces with anisotropic pillar structures, generating a unidirectional wicking behavior to augment capillary-driven force when liquid propagation corresponds with the pillar tilted direction. Further, we first experimentally determined the effect of the anisotropic pillar structures concerning wicking direction on heat transfer in subcooled flow boiling (40 K). When micropillars were tilted toward the convective flow direction (compared to against the flow direction), the unidirectional wicking enhanced the critical heat flux (CHF) by 31%, showing a directional dependence on tilted pillars. The anisotropic wicking surfaces can apply to high-power applications with their unique unidirectional wicking-driven heat transfer and high substrate selectivity.