Dong Xiuli, Chan Kit-Ying, Yin Xuemin, Zhang Yu, Zhao Xiaomeng, Yang Yunfei, Wang Zhenyu, Shen Xi
Department of Aeronautical and Aviation Engineering, The Hong Kong Polytechnic University, Hong Kong SAR, People's Republic of China.
The Research Institute for Advanced Manufacturing, The Hong Kong Polytechnic University, Hong Kong SAR, People's Republic of China.
Nanomicro Lett. 2025 Apr 29;17(1):240. doi: 10.1007/s40820-025-01766-5.
Hygroscopic hydrogel is a promising evaporative-cooling material for high-power passive daytime cooling with water self-regeneration. However, undesired solar and environmental heating makes it a challenge to maintain sub-ambient daytime cooling. While different strategies have been developed to mitigate heat gains, they inevitably sacrifice the evaporation and water regeneration due to highly coupled thermal and vapor transport. Here, an anisotropic synergistically performed insulation-radiation-evaporation (ASPIRE) cooler is developed by leveraging a dual-alignment structure both internal and external to the hydrogel for coordinated thermal and water transport. The ASPIRE cooler achieves an impressive average sub-ambient cooling temperature of ~ 8.2 °C and a remarkable peak cooling power of 311 W m under direct sunlight. Further examining the cooling mechanism reveals that the ASPIRE cooler reduces the solar and environmental heat gains without comprising the evaporation. Moreover, self-sustained multi-day cooling is possible with water self-regeneration at night under both clear and cloudy days. The synergistic design provides new insights toward high-power, sustainable, and all-weather passive cooling applications.
吸湿水凝胶是一种很有前途的蒸发冷却材料，可用于具有水自再生功能的高功率被动式日间冷却。然而，不期望的太阳加热和环境加热使得维持低于环境温度的日间冷却成为一项挑战。虽然已经开发出不同的策略来减轻热量获取，但由于热传输和蒸汽传输高度耦合，它们不可避免地牺牲了蒸发和水再生。在此，通过利用水凝胶内部和外部的双对齐结构来实现热传输和水传输的协同，开发了一种各向异性协同保温-辐射-蒸发（ASPIRE）冷却器。该ASPIRE冷却器在直射阳光下实现了令人印象深刻的平均低于环境温度约8.2°C的冷却温度以及311 W/m的显著峰值冷却功率。进一步研究冷却机制表明，ASPIRE冷却器在不影响蒸发的情况下减少了太阳和环境热量获取。此外，在白天晴朗和多云的情况下，夜间通过水自再生都可以实现持续多日的自我维持冷却。这种协同设计为高功率、可持续和全天候被动冷却应用提供了新的见解。
