Wang Shanlin, Zhao Xiaofeng, Wu Xian, Zhang Qingyu, Teng Yuancheng, Ahuja Rajeev, Zhang Youfa
State Key Laboratory for Environment-Friendly Energy Materials, School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, P. R. China.
Condensed Matter Theory Group, Materials Theory Division, Department of Physics and Astronomy, Uppsala University, 75120 Uppsala, Sweden.
Langmuir. 2021 Jan 12;37(1):553-560. doi: 10.1021/acs.langmuir.0c03256. Epub 2021 Jan 4.
Joule-heat-driven directional transport of liquid droplets has comprehensive engineering applications in various water and thermal management, cooling systems, and self-cleaning. Generally, the driving force for the transport of liquid droplets was always observed at an extremely high Leidenfrost temperature, which limits the potential application between liquid boiling and Leidenfrost points. In this work, we design a new strategy to directionally drive the transport of droplets by blockading the vapor cushion at a temperature much lower than the Leidenfrost point. On the surface of the microhole arrays, we observed the continuous rebound behavior of ethanol droplets at = 110 °C. Employing the thermal multiphase lattice Boltzmann model, the continuous rebound behavior was reproduced, verifying that the driving force was provided by the blockaded vapor pressure in microholes. By cooperating with the Laplace pressure difference, we directionally transport ethanol and water droplets on the horizontal asymmetrical concentric microridge surface. The horizontal velocity of water is 11.25 cm/s at = 180 °C, similar to the traditional ratchets at the Leidenfrost point. The design of microtextures enriches the fundamental understanding of how to drive droplets at far below the Leidenfrost point and pushes the application in nongravity-driven self-cleaning and cooling systems.
焦耳热驱动的液滴定向输运在各种水和热管理、冷却系统及自清洁等方面具有广泛的工程应用。通常，液滴输运的驱动力总是在极高的莱顿弗罗斯特温度下才能观察到，这限制了其在液体沸腾和莱顿弗罗斯特温度点之间的潜在应用。在这项工作中，我们设计了一种新策略，通过在远低于莱顿弗罗斯特温度的条件下封锁蒸汽垫来定向驱动液滴输运。在微孔阵列表面，我们观察到乙醇液滴在110°C时的连续反弹行为。采用热多相格子玻尔兹曼模型，再现了这种连续反弹行为，证实驱动力是由微孔中被封锁的蒸汽压力提供的。通过与拉普拉斯压差协同作用，我们在水平非对称同心微脊表面上定向输运乙醇和水滴。在180°C时，水的水平速度为11.25厘米/秒，与传统的莱顿弗罗斯特点处的棘轮相似。微纹理的设计丰富了对如何在远低于莱顿弗罗斯特温度下驱动液滴的基本认识，并推动了其在非重力驱动的自清洁和冷却系统中的应用。
