  Sustainable liquid cooling solutions are recognized as the future of thermal
management in the chip industry. Among them, the phase change heat transfer
devices such as heat pipes and vapour chambers have shown tremendous potential.
These devices rely on the physics of capillary-driven thin-film evaporation
which is inherently coupled with the design and optimization of the evaporator
wicks used in these devices. Here, we introduce a biomimetic evaporator wick
design inspired by the peristome of the Nepenthes alata that can achieve
significantly enhanced evaporative cooling. It consists of array of
micropillars with multiple wedges along the sidewall of each micropillar. The
efficacy of the wedged micropillar is evaluated based on a validated numerical
model on the metrics of dryout heat flux and effective heat transfer
coefficient. The wedge angle is chosen such that wedged micropillars cause
liquid filaments to rise along the micropillar vertical walls. This results in
a significant increase in thin-film area for evaporation. Additionally, the
large mean curvature of the liquid meniscus produces strong capillary pumping
pressure and simultaneously, the wedges increase the overall permeability of
the wick. Consequently, our model predicts that the wedged micropillar wick can
attain ~234% enhancement of dryout heat flux compared to a conventional
cylindrical micropillar wick of similar geometrical dimensions. Moreover, the
wedged micropillars can also attain higher effective heat transfer coefficient
under dryout conditions thus outperforming the cylindrical micropillar in terms
of heat transfer efficiency. Our study provide insight into the design and
capability of the biomimetic wedged micropillars as an efficient evaporator
wick for various thin-film evaporation applications.
