Collaborative Research: Understanding, Mitigating, and Controlling Frost Formation Through the Use of Biphilic and Hybrid Surfaces Under Static and Dynamic Conditions

#1604183 Betz，Amy R.结霜是一种常见的现象，它会惩罚能源消耗;它会在冰箱中积聚，覆盖车窗，并阻止热泵空调正常工作。它还对飞机安全性和可靠性等应用产生有害影响。本研究将探讨结合联合收割机吸水和斥水区域的新表面，以防止和控制霜冻的形成。在结霜过程中，水以汽、液、固三相共存。通过使用具有吸水区域和斥水区域的弹性和最佳定位的交错图案的表面，在水冻结之前控制水的输送。初步结果表明，控制水在液相和气相中的传输可以显着增加冻结发生所需的时间，甚至在某些温度范围内完全防止霜冻。即使水最初在表面上冻结，霜也会继续三维生长，导致厚厚的霜。霜层的生长主要取决于水汽输送。 可以选择性地吸引和排斥水蒸气的表面具有改变霜生长模式和限制霜层厚度的潜力。这项工作的目的是调查表面和翅片结构上的吸水和斥水区域的各种模式，并发现可以完全防止结霜的最宽温度范围，以及确定如何最佳地控制结霜，以显著降低应用中的能源消耗，其中的条件超出防霜。该项目将从根本上研究新的混合亲水性和疏水性表面，这些表面产生并合并过冷水滴，即在冻结温度及以下保持液相的水滴。交错涂层实际上将这些液滴重新定位在传热表面上。这些新概念减轻了霜的生长，控制了霜负荷，并最大限度地提高了能量转换效率。这项研究将进行合作：堪萨斯州立大学将开发表面并研究静止条件下的液滴，而奥本大学将表征翅片结构上对流动态条件下新表面的抗霜性能的恢复力。本研究的目的是促进了解这些涂层如何影响霜的成核和结构在生长过程中。拟议研究的一项重大创新将是坚固的表面，可显着减少霜层，这将大大减少热阻和气流堵塞。这将立即提高制冷系统和风冷冷凝器的能量转换效率。这项工作的实验结果也将用于加强研究小组开发的模型，用于设计防冻表面。

#1604183Betz, Amy R.Frost formation is a common occurrence that penalizes energy consumption; it builds up in freezers, covers car windows, and prevents heat pump air-conditioners from properly functioning. It also has harmful effects in applications such as airplane safety and reliability. This research will investigate new surfaces that combine water-attracting and water-repelling regions to prevent and control frost formation. During the frost formation process, water coexists as vapor, liquid, and solid phases. By using surfaces with resilient and optimally positioned interlaced patterns of water-attracting and water-repelling regions, the transport of the water is controlled before it freezes. Preliminary results show that controlling the transport of water in the liquid and vapor phases can significantly increase the amount of time it takes for freezing to occur and even prevent frost altogether for certain temperature ranges. Even after water initially freezes on a surface, frost continues to grow three-dimensionally leading to thick build-up of frost. The growth of the frost layer is predominately dependent of water vapor transport. A surface that can selectively attract and repel water vapor has the potential to change the frost growth pattern and to limit the thickness of the frost layer. The objective of this work is to investigate various patterns of water-attracting and water-repelling regions on surfaces and on fin structures and to discover the widest temperature range possible were frost can be completely prevented as well as determine how frost formation can be optimally controlled for significantly less energy consumption in applications in which the conditions are beyond frost prevention. This project will fundamentally investigate new mixed hydrophilic and hydrophobic surfaces that generate and coalesce supercooled water droplets, that is, water droplets that remain in the liquid phase at and below freezing temperature. The interlaced coatings pragmatically relocate these droplets on the heat transfer surfaces. These new concepts mitigate frost growth, control frost loading, and maximizes energy conversion efficiencies. The investigation will be approached collaboratively: Kansas State University will develop the surfaces and study the droplets in quiescence conditions while Auburn University will characterize the resilience of the anti-frost properties of the new surfaces under convective dynamic conditions on fin structures. The objective of this research is to advance the understanding of how these coatings affect the frost nucleation and structure during growth. A major innovation from the proposed research will be a robust surface that provides significantly reduced frost layer, which will greatly minimize thermal resistance and air flow blockage. This will immediately augment the energy conversion efficiencies of refrigeration systems and air-cooled condensers. The experimental results from this work will be also used to strengthen the models developed by the research team for designing frost mitigating surfaces.