Hybrid wick evaporator for electronic devices

Advances in emerging technologies such as AI semiconductors, high-performance mobile devices, power electronics, and aerospace/defense systems require thermal management solutions capable of handling increasingly high heat fluxes within limited spaces. For this reason, phase-change-based thermal management technologies, which can provide both high heat transfer performance and passive heat transport capability, are becoming increasingly important. Phase-change-based thermal management devices, such as vapor chambers, heat pipes, cold plates, and heat exchangers, rely on capillary-driven porous wicks to transport liquid and sustain evaporation. A major challenge in wick design is the trade-off between heat transfer coefficient and critical heat flux. Thin and dense wicks can enhance evaporation heat transfer, but their limited liquid supply capability can lead to premature dry-out. Multiscale hybrid wicks offer a promising solution to overcome this limitation by combining a coarse liquid-supply layer with a thin evaporator layer. However, their dry-out behavior and design principles remain insufficiently understood. To address this issue, this study aims to establish a systematic design framework for multiscale hybrid wicks. To achieve this, we identified the dry-out mechanisms that govern the performance of multiscale hybrid wicks and proposed a design criterion to predict the dry-out type. We also developed an experimentally validated performance prediction model and an artificial neural network-based surrogate model to efficiently optimize wick structures over a wide design space. The optimized wick design achieved a significantly enhanced critical heat flux while maintaining low thermal resistance.