Collaborative Research: A Micropatterned Wettability Approach for Superior Boiling Heat Transfer Performance

CBET-1235867PIs: Daniel Attinger（爱荷华州立大学）和C. Megaridis （UIC）这个跨机构项目跨越了热流体工程、材料科学和优化领域，主要目标是设计、制造和研究被称为“超亲性”的新型表面。这些微观和纳米结构的表面将超疏水区（对水有很强的亲和力）和超疏水区（对水蒸气有很强的亲和力）并置。因此，它们通过以平行和最佳的方式控制汽相和液相的传输，在池沸中表现出优越的性能。该研究将开发一种新型的金属涂层工艺，该工艺可扩展并与工业热交换器相关。主要的科学挑战在于理解、控制和优化超亲水性表面上的沸腾现象。双亲性和超亲性表面将首次在技术上相关的金属衬底上制造。该技术基于可喷涂的图案涂料，美国在该工业领域的领导地位正受到海外的挑战。该研究为双亲和超亲表面的沸腾强化奠定了理论基础。这项工作具有挑战性，因为沸腾涉及多相和多尺度输运现象（蒸发始于亚微米厚的薄膜，而分离的气泡只有毫米大小）和严重的瞬态过程。为了协助设计和实验，将进行建模工作。对于简单的表面形貌（或疏水和亲水结构域的模式），将开发分析模型以定性的方式解释池沸腾增强。计算流体动力学模拟也将进行，以帮助理解实验数据，确定负责沸腾增强的动力学机制，并评估复杂表面地形的性能。这项工作将以模式设计优化方法为特色，以确定沸腾性能的最佳地形。新型超亲水性表面的性能将通过一系列实验进行评估，包括表面润湿性测量、涂层物理表征、高速可视化以及成核和池沸腾曲线。该研究涉及各种多学科主题的丰富基本现象，旨在提供一种创新的解决方案，以在沸腾配置中以优越的速率传递热量。这项工作的发展将影响热交换器等其他技术，热交换器广泛应用于大多数能源密集型行业，仅在美国每年就消耗超过15千万亿英热单位。因此，这项研究产生的非增量改进有可能产生巨大的能源节约，进而减少能源浪费和环境污染。两名研究生将在这个项目中接受教育，该团队将向芝加哥地区未被充分代表的少数民族伸出援手。

CBET-1235867PIs: Daniel Attinger (Iowa State Univ.) and C. Megaridis (UIC)This cross-institutional project straddles the areas of thermofluid engineering, materials science and optimization, with main goal to design, fabricate and study novel surfaces that are called ?superbiphilic.? These micro- and nanostructured surfaces juxtapose superhydrophobic areas (with strong affinities for water) with superhydrophobic areas (with strong affinities for water vapor). As such, they show superior performance in pool boiling by controlling the transport of the vapor and liquid phases in a parallel and optimal manner. The study will develop a novel coating-on-metal process, which is scalable and relevant to industrial heat exchangers. The main scientific challenge lies in understanding, controlling and optimizing boiling phenomena on the superbiphilic surfaces. For the first time, biphilic and superbiphilic surfaces will be fabricated on technically relevant, metallic substrates. The technology is based on sprayed-on patternable coatings, an industrial sector where US leadership is challenged from overseas. The research will develop a theoretical science base for boiling enhancement on biphilic and superbiphilic surfaces. The work is challenging because boiling involves multiphase and multiscale transport phenomena (evaporation starts in a sub-micrometer thick film, while detaching bubbles are millimeter-sized) and severely transient processes. To assist with the design and experiments, a modeling effort will be carried through. For simple surface topographies (or patterns of hydrophobic and hydrophilic domains), analytical models will be developed to explain the pool boiling enhancement in a qualitative manner. Computational fluid dynamic simulations will also be performed, to help understand the experimental data, identify the dynamic mechanisms responsible for the boiling enhancement, and evaluate the performance of complex surface topographies. The effort will feature a pattern design optimization approach to determine optimum topographies for boiling performance. The performance of the novel superbiphilic surfaces will be evaluated by a series of experiments, including surface wettability measurements, coating physical characterization, high speed visualization, as well as nucleation and pool boiling curves.The research, which involves rich fundamental phenomena in a variety of multidisciplinary topics, intends to deliver an innovative solution to transferring heat at superior rates in boiling configurations. The developments from this work will affect -among other technologies- heat exchangers, which are widely used in most energy-intensive industries, which collectively consume over 15 quadrillion Btu/yr in the US alone. Consequently, the non-incremental improvements resulting from this research have the potential to generate tremendous energy savings, and in turn, reduce energy waste and environmental pollution. Two graduate students will be educated in this program, and the team will reach out to underrepresented minorities in the Chicago area.