Direct Thermoacoustic Cooling of Cryogenic Hydrogen

为了应对气候变化，人类必须减少对化石燃料的依赖，并为工业、交通和消费者找到替代能源。使用可再生能源生产的氢气被认为是未来最有前途的燃料之一，并且在与氧气反应时不会排放有害污染物。然而，作为最轻的元素，气态形式的氢需要大的容器来储存，并且在许多应用中被认为是不切实际的。液氢是一种非常有吸引力的紧凑能源，但它只能在非常低的温度下存在。目前用于氢气液化和储存的冷却技术效率相当低。为了使氢经济可行，本项目探索了一种潜在有效的新型声学方法，用于低温氢的耦合冷却-转换。相关的教育和推广活动旨在通过开发能源相关课程、K-12学生暑期课程、专业短期课程和低温氢系统教科书的材料来改善工程教育。制备用于液化和随后低能态储存的氢的必要步骤包括低温冷却和自旋转化。这些过程可以通过在多孔基质中使用热声热泵来潜在地结合起来，多孔基质也可以作为催化床，加速流动的正氢转化为准氢。对这一综合过程的探索以及相关的热传递、流体流动、量子跃迁、动态机制和系统工程构成了拟议研究的智力意义。建模工作将包括开发一个降阶框架，用于分析用于冷却低温氢的热声催化系统，并建立高保真的计算模拟，同时结合来自不同科学和技术领域的模型。实验系统将被设计、建造和测试，用于分析验证和实际演示冷却低温氢的新方法。该项目产生的结果和产品将有助于建立高效低温氢基能源系统的实际设计方法。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。

To address climate change, Humanity must reduce reliance on fossil fuels and find alternative ways to generate energy for industry, transportation, and consumers. Hydrogen, when produced using renewable energy sources, is considered as one of the most promising fuels for the future, and does not emit harmful pollutants when reacting with oxygen. However, being the lightest element, hydrogen in the gaseous form requires large containers for storage and is considered impractical for many applications. Liquid hydrogen is a very attractive compact energy source, but it can exist only at very low temperatures. Current cooling techniques for both liquefaction and storage of hydrogen are rather inefficient. To help make the hydrogen economy viable, a potentially efficient novel acoustic method for coupled cooling-conversion of cryogenic hydrogen is explored of this project. The accompanying educational and outreach activities aim at improving engineering education by developing materials for energy-related courses, summer programs for K-12 students, professional short courses, and a textbook on cryogenic hydrogen systems.The necessary steps to prepare hydrogen for liquefaction and subsequent storage in the low energy state include cryogenic cooling and spin-conversion. These processes can be potentially combined by employing thermoacoustic heat pumping in a porous matrix which will also serve as a catalytic bed, accelerating conversion of flowing orthohydrogen into parahydrogen. The exploration of this combined process and associated thermal transport, fluid flow, quantum transitions, dynamic regimes, and system engineering constitutes the intellectual significance of the proposed research. Modeling efforts will include development of a reduced-order framework for analysis of thermoacoustic-catalytic systems for cooling cryogenic hydrogen and setting up high-fidelity computational simulations, while incorporating models from different scientific and technical areas. Experimental systems will be designed, built, and tested for analysis validation and practical demonstrations of novel methods for cooling cryogenic hydrogen. Results and products generated in this project will help establish methods for practical design of efficient cryogenic hydrogen-based energy systems.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.