RII Track-4: Tailored Flow Boiling Mechanisms Using 3D Printed Multifunctional Wick Structures

高效和可持续的发电对美国的能源供应/安全和经济至关重要，并且以热电系统为主，因为2018年83%的电力来自化石燃料和核能。蒸汽发生器（即流动锅炉）的性能限制了电力生产的效率，这是由于多余的蒸汽毯造成局部过早干化造成的。为了解决这一挑战，提出了一种多功能灯芯结构，用于有效的液-气分离，同时提高了当前在传热系数和每给定表面积的最大传热率方面的技术限制，而不会产生显著的液压降。所提出的研究的关键成功需要先进的制造方法来提出具有复杂几何形状的多功能灯芯结构。PI将与内布拉斯加州大学林肯分校（UNL）的一位合作者合作，使用纳米工程研究核心设施（NERCF）最先进的高分辨率金属3D打印机进行研究。此外，该奖学金将大大加强华盛顿州立大学和UNL之间的合作。获得的新知识将被运用到教育计划中，这将赋予未来的工程劳动力以力量。流动沸腾系统是各种能源和热管理应用的关键。然而，由于系统对小型化和大功率能耗的要求，其散热水平有望超过传统流动沸腾系统的最大冷却功率——临界热流密度（CHF）。CHF是由于流动出口过早干化，导致两相流失稳导致系统灾难性燃尽。尽管进行了大量的研究，但目前还没有可行的解决方案来减轻长流道的CHF。该研究的目的是利用开发的机制模型、3D打印多功能灯芯（即鱼翅状微孔结构）和原位/非原位实验验证的协同组合，了解量身定制的两相流不稳定性和相变传热机制。拟议的研究将集中于三个研究重点：(a)开发机制模型，预测CHF和热传递系数（HTC）机制；(b)与内布拉斯加大学林肯分校的合作者合作，利用纳米工程研究核心设施（NERCF）最先进的高分辨率金属3D打印机Lumex Avance-25，开发具有可控微孔尺寸/几何形状的增材制造；(c)增强CHF和HTC的原位/非原位实验验证。研究成果使高效、可扩展和强大的流动沸腾系统的发展成为可能，包括发电厂、电子冷却和航空航天应用。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 and sustainable electrical power generation is critical to the U.S. energy supply/security and economy, and it is dominated by thermo-electric systems as the 83% of the electricity in 2018 has been generated from fossil fuels and nuclear energy. The efficiency of the electrical power production is bottlenecked by the performance of a steam generator, i.e., flow boiler, which is caused by a local premature water dryout from excessive unwanted vapor blankets. To address this challenge, the proposed research will a multifunctional wick structure is proposed for effective liquid-vapor separation, to simultaneously advance current technical limits on heat transfer coefficient and maximum heat transfer rate per given surface area without creating significant hydraulic pressure drop. A key success of the propose research requires advanced manufacturing approach for the proposed multifunctional wick structure with complex geometries. The PI will conduct the research working with a collaborator at University of Nebraska, Lincoln (UNL) using the-state-of-the-art metallic 3D printer with the high resolution at Nano-Engineering Research Core Facility (NERCF). Also, this fellowship will greatly strengthen the collaboration between the WSU and UNL. The obtained new knowledge will be implemented into the education plans, which empower future engineering workforce.A flow boiling system is crucial to various energy and thermal management applications. However, as the system demands miniaturization and high power energy consumption, the level of the heat dissipation is expected to exceed the maximum cooling power of the conventional flow boiling system, Critical Heat Flux (CHF). The CHF is caused by the premature dryout at the flow exit, resulting in catastrophic system burnout, which is caused by two-phase flow instability. Despite of extensive research, currently there is no viable solution to mitigate CHF for long flow channel. The objective of the proposed research is to understand tailored two-phase flow instability and phase-change heat transfer mechanisms using the synergistic combination of the developed mechanistic model, 3D printed multifunctional wicks, i.e., shark-fin-like microporous structures, and in-situ/ex-situ experimental validations. The proposed research will focus on three research thrusts: (a) development of mechanistic models, predicting the tailoring CHF and Heat Transfer Coefficient (HTC) mechanisms, (b) development of the additive manufacturing with the controlled micropore sizes/geometries, while working with collaborator at University of Nebraska, Lincoln by using the-state-of-the-art metallic 3D printer with the high resolution, Lumex Avance-25 at Nano-Engineering Research Core Facility (NERCF), and (c) in-situ/ex-situ experimental validations of enhanced CHF and HTC. The research outcomes enable the developments of efficient, scalable, and robust flow boiling systems including power plant, electronic cooling, and aerospace applicationsThis 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.