Dielectric nanofluids for electrostatic machines

国家人口的增长对传统和新兴技术的电动机产生了前所未有的需求。电力的新用途，包括电动汽车、支持互联网的服务器群和高速铁路，都增加了对电动机的需求。此外，直接驱动的风力涡轮机和无人机可以从其传动系统的重新配置中受益。传统的电磁马达使用镝和钕等稀土元素，其未来的可用性尚不确定。静电电机可以可持续地制造，但在许多应用中需要改进扭矩输出。增加的扭矩可以通过增加电机内流体的介电常数来实现。添加小颗粒可以增加流体的介电常数，但颗粒-流体混合物可能变得过于粘稠，不适用于电机应用。在这个项目中，数学模型和计算机模拟将用于设计具有高介电常数和低粘度的颗粒-流体混合物。该研究团队将与威斯康星大学化学教育研究所合作，指导本科生为K-12学生构建静电演示。这些示范将在不同的场地进行，让公众了解静电的新应用。静电电机所需的大电场会引起电机内悬浮颗粒的场致聚集。颗粒的聚集反过来又导致悬浮液粘度的大幅增加，从而降低了电机性能。在悬浮液中使用布朗纳米粒子可以避免粒子聚集，这样热运动可以克服场致力。由范德华力引起的粒子聚集可以通过空间稳定来避免。粒子级模拟将用于确定颗粒大小和浓度、电场强度和频率、立体层性质以及悬浮液的宏观介电和流变性能之间的关系。这项工作的结果将使从业者能够为各种静电电机应用设计有效的纳米颗粒悬浮液。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。

Increases in the nation's population have created an unprecedented demand for electric motors in conventional and emerging technologies. New uses of electricity, including electric vehicles, server farms to support the internet, and high-speed rail, have contributed additional demands for electric motors. Furthermore, direct drive wind turbines and drones could benefit from reconfigurations of their drive trains. Conventional electromagnetic motors utilize rare earth elements such as dysprosium and neodymium whose future availabilities are uncertain. Electrostatic motors can be made sustainably, but improvements in torque output are required for many applications. Increased torque can be achieved by increasing the dielectric constant of the fluid within the motor. Adding small particles can increase the fluid's dielectric constant, but the particle-fluid mixture can become too viscous for motor applications. In this project, mathematical models and computer simulations will be used to engineer particle-fluid mixtures that have high dielectric constants and low viscosities. The research team will partner with the University of Wisconsin's Institute for Chemical Education to guide undergraduate students in constructing demonstrations of electrostatics intended for K-12 students. The demonstrations will be used at various venues to engage the public in novel applications of electrostatics.The large electric fields required for electrostatic motors can cause field-induced aggregation of the particles in the suspension within the motor. Aggregation of the particles leads, in turn, to large increases in the suspension viscosity, which diminishes motor performance. Particle aggregation can be avoided by employing Brownian nanoparticles in the suspension, such that thermal motion can overcome the field-induced forces. Aggregation of the particles due to van der Waals forces can be avoided by steric stabilization. Particle-level simulations will be employed to determine the relationships between particle size and concentration, electric field strength and frequency, steric layer properties, and the macroscopic dielectric and rheological properties of the suspensions. The results of this work will enable practitioners to engineer effective nanoparticle suspensions for a variety of electrostatic motor applications.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.