CAREER: Investigation of Boiling Heat Transfer Mechanisms and their Enhancement using Biotemplated Nanostructures

相变传热在工业中无处不在，它在发电、化学加工、水净化和HVAC系统中起着至关重要的作用。适度增强相变传热可以显著节省能源和成本。此外，创新相变传热系统的重要性不仅在于其对能源使用、环境和水资源的影响，还在于下一代高功率电子和光子系统的热管理需求。最近的研究表明，由纳米结构组成的高表面积涂层可以大大提高相变过程中的性能，特别是在沸腾传热过程中。然而，关于纳米结构涂层增强传热的潜在物理机制仍然存在许多问题。该项目的目标是利用生物模板纳米制造系统地研究纳米结构涂层影响和增强相变传热的基本机制。研究结果将整合到面向高中生和大学生的纳米科学技术教育活动中，包括动手纳米制造和热表征实验，纳米热能学习社区，以及学生参与纳米科学研究的机会。该职业发展奖项的科学目标是利用生物模板纳米制造的简单性和灵活性来研究纳米结构涂层在沸腾过程中影响液相到气相变化的基本机制。这将利用烟草花叶病毒（TMV）的自组装和金属化来制造可调谐的表面结构，用于新的和可验证的热流体表征，从而实现具有异质结构的高性能表面。关键的形态和材料特性将以前所未有的控制进行调整，允许系统的实验表征，与沸腾现象的直接关联，以及确定新的机制模型。基于红外测温和共聚焦扫描激光显微镜的先进成像技术将允许在沸腾/蒸发过程中同时可视化和测量湿润状态、表面温度和局部动态热通量。由于生物模板与低电导率和低熔融温度聚合物材料的兼容性，这些测量将成为可能。最后，将设计具有复杂和异质结构的新型表面（通过生物模板实现），以增强煮沸各个阶段的性能。这些包括材料面内变化和热导率的表面，以及超亲水性纳米结构。

CBET-1454407PI: McCarthy, MatthewPhase-change heat transfer is ubiquitous in industry, and it plays a critical role in electrical power generation, chemical processing, water purification, and HVAC systems. Modest enhancements in phase-change heat transfer can generate significant savings in energy and costs. Furthermore, innovative phase-change heat transfer systems are important not only due to their effects on energy usage, the environment, and water resources, but also due to the thermal management needs of next-generation high-power electronic and photonic systems. Recent studies have shown that high-surface-areas coatings comprised of nanostructures can be used to substantially increase performance during phase-change processes, and, in particular, during boiling heat transfer. However, numerous questions remain regarding the underlying physical mechanisms by which nanostructured coatings enhance heat transfer. The goal of this project is to utilize biotemplated nanofabrication to systematically investigate fundamental mechanisms by which nanostructured coatings affect and enhance phase-change heat transfer. Results from the research will be integrated into educational activities in nanoscale science and technology for high-school and university students, including a hands-on nanofabrication and thermal characterization experiment, a nano-thermal energy learning community, and opportunities for students to participate in the nanoscience research.The scientific objective of this CAREER development award is to leverage the simplicity and flexibility of biotemplated nanofabrication to investigate fundamental mechanisms by which nanostructured coatings affect liquid-to-vapor phase change during boiling. This will be accomplished using the self-assembly and metallization of the Tobacco mosaic virus (TMV) to fabricate tunable surface structures for novel and probative thermofluidic characterizations, leading to the realization of high-performance surfaces with heterogeneous architectures. Critical morphological and material properties will be tuned with unprecedented control, allowing systematic experimental characterizations, direct correlations to boiling phenomena, and the determination of new mechanistic models. Advanced imaging techniques based on IR thermometry and confocal scanning laser microscopy will permit simultaneous visualization and measurement of the wetting state, surface temperature, and local dynamic heat flux during boiling/evaporation. These measurements will be made possible due to the compatibility of biotemplating with low-conductivity and low-melting temperature polymeric materials. Lastly, novel surfaces with complex and heterogonous architectures (made possible via biotemplating) will be engineered for enhanced performance across all stages of boiling. These include surfaces with in-plane variations in materials and thermal conductivity, combined with superhydrophilic nanostructures.