Collaborative Research: Enhanced electricity generation through liquid flow over durable slippery Surfaces

高效的水电技术通过提供可再生能源和减少温室气体排放，支持国家繁荣和能源安全。传统的水力发电技术利用水坝和笨重的电磁发电机将落水的动能转化为电能。虽然水力发电是一种可再生能源，但传统的方法往往会对环境产生不利影响，而且电力效率很低。值得注意的是，当液体流过表面时也可以产生电力，而产生的电力可以在不使用水坝或电磁发电机的情况下收集。通过表面上的液体流动来发电是一种通用的方法，它可以收集在全球水循环中以各种形式储存的能量（例如水流、自然蒸发、雨滴和海浪）。然而，这种能量产生方法还不能产生期望的电压输出。为了增加液体流过表面时产生的电力，该项目将研究液面界面特性对性能的影响；有利的性能包括显著的界面电荷，小的液体移动摩擦，和持久的流动。与新型工程界面上的液体流动相关的知识将改变可持续能源生产、清洁水和生物医学设备设计的关键技术。调查人员将开展教育活动，重点关注女性在STEM领域的专业发展和参与，特别是K-12和本科生，以培养多样化的未来工程劳动力。本提案的总体目标是发现工程界面上的电动力学的新基础；这些知识将用于设计一种新型的、耐用的光滑表面，以提高发电量。传统上，超疏水表面通过减少界面摩擦来提高电动流动中的能量转换。然而，使用超疏水表面用于此目的存在两个重大挑战：由于不带电的液-气界面导致界面电荷减少，以及液-气界面在流体流动下的耐久性较差。为了应对这些挑战并实现总体目标，将采用综合实验和计算方法来产生必要的知识。任务1需要对充满油的光滑粗糙表面上的电动流动的流势进行实验表征。这一努力将导致理解液油界面和表面粗糙度对增强界面电荷的影响。任务2是实验表征和直接数值模拟在不同油性质和表面纹理几何参数下液-油界面在流动中的稳定性和耐久性。揭示了这些控制参数对表面耐久性的影响。通过任务1和任务2获得的见解将应用于设计耐用的光滑表面，与使用固体或超疏水表面相比，它将使电压产生增加两个数量级。这种新颖耐用的光滑表面将改变电动能源设备的发展，应用范围从智能电子设备的小型原位电源到蓝色能量收集的大规模能源系统。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Efficient hydropower technologies support national prosperity and energy security by providing a renewable energy source and reducing greenhouse gas emissions. Traditional hydropower technologies convert the kinetic energy of falling water to electricity using dams and bulky electromagnetic generators. Although hydropower is a renewable energy source, traditional approaches often come with adverse environmental impacts and poor power efficiency. Notably, electricity can also be generated when liquid flows over a surface, and the resulting electricity can be harvested without using dams or electromagnetic generators. Generating hydropower via liquid flow over a surface is a versatile approach that would enable the harvesting of energy stored in various forms across the global water cycle (e.g., water flow, natural evaporation, raindrops, and ocean waves). However, such energy generation approaches do not yet yield the desired voltage output. To increase the generated electricity when liquid flows over a surface, this project will examine the impact of the liquid-surface interfacial properties on performance; favorable properties include significant interface charges, small liquid moving friction, and being durable under flow. The generated knowledge related to liquid flow over novel engineered interfaces will transform key technologies in the sustainable generation of energy, clean water, and the design of biomedical devices. The investigators will conduct educational activities that focus on the professional development and participation of women in STEM, especially K-12 and undergraduate students, to train a diverse future engineering workforce.The overarching objective of this proposal is to discover new fundamentals of electrokinetics over engineered interfaces; this knowledge will be used to design a novel, durable slippery surface for improved electricity generation. Superhydrophobic surfaces are traditionally used to enhance energy conversion in electrokinetic flow by reducing interface friction. However, there are two significant challenges associated with using superhydrophobic surfaces for this purpose: the reduced interface charges due to non-charged liquid-air interfaces and the inferior durability of liquid-air interfaces under fluid flow. To address these challenges and achieve the overarching objective, an integrated experimental and computational approach will be employed to generate the necessary knowledge. Task 1 entails the experimental characterization of the streaming potential of electrokinetic flow over oil-filled slippery rough surfaces. This effort will lead to an understanding of the effects of liquid-oil interfaces and surface roughness on enhancing interface charges. Task 2 entails experimental characterization and direct numerical simulation of the liquid-oil interface stability and durability in flow under different oil properties and geometrical parameters of the surface texture. The influences of these control parameters on surface durability will be revealed. The insights gained through Tasks 1 and 2 will then be applied to design a durable slippery surface that will increase voltage generation by two orders of magnitude over that of using a solid or superhydrophobic surface. The novel durable slippery surface will transform the development of electrokinetic energy devices for myriad applications, ranging from small-scale in situ power sources for smart electronics to scaled-up energy systems for blue energy harvesting.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.