EAGER: Uncovering the Physical Mechanism behind Flow Boiling Critical Heat Flux

许多行业，包括能源、航空航天、国防和消费电子行业，能源利用率都在显著增加。目前使用空气或水流的冷却系统通常不能有效地提取热量并保持合理的操作温度。液体的沸腾是一种非常有效的冷却机制，但沸腾系统可以提取多少热量是有限制的，由临界热通量定义。超过临界热通量会导致发热系统或设备的故障。该项目的首要目标是了解临界热通量背后的物理学。 这种理解可以用来避免沸腾系统的故障。该项目的教育和推广目标是通过为凯斯西储大学的“创新导论”项目开发一个模块来补充研究活动，该项目是一个新的校园范围更广泛的影响战略的核心，为中学教育工作者提供应用核心科学概念来理解简单冷却系统的经验。池沸腾现象的实验室演示已计划补充该模块的教学部分，重点是由于在自然系统中的沸腾相变。它已被证明，流动沸腾临界热通量可以由流体动力学液-汽不稳定性发生在流动触发。然而，迄今为止，还没有对这一现象进行彻底的验证，以确定其背后的机制。在本项目中，研究人员计划通过使用高速成像和粒子图像测速测量相结合，探索流动沸腾过程中的界面流动动力学，从而对临界热通量背后的机制有一个基本的了解。利用获得的数据，将开发一个机械模型来预测临界热通量。该奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

Many industries including those in energy, aerospace, defense, and consumer electronics sectors are seeing a significant increase in energy utilization. Current cooling systems that use air or water flows are often incapable of extracting the heat effectively and maintaining reasonable operating temperatures. Boiling of liquids is a very effective cooling mechanism, but there is a limit on how much boiling systems can extract, defined by the critical heat flux. Exceeding the critical heat flux can cause a failure of the heat-generating system or device. The overarching goal of this project is the understand the physics behind the critical heat flux. This understanding can then be used to to avoid failure in boiling systems. The educational and outreach goal for the project is to complement the research activity by developing a module for Case Western Reserve University’s “Introduction to Innovation” program, the centerpiece of a new campus-wide broader impact strategy, to give middle school educators experience in applying core scientific concepts to understanding simple cooling systems. A lab demonstration of the pool boiling phenomena has been planned to supplement the teaching section of the module to focus on phase-transformation due to boiling in natural systems.It has been shown that flow boiling critical heat flux can be triggered by hydrodynamic liquid-vapor instabilities occurring in the flow. However, to date, no thorough validation of the phenomena has been performed to ascertain the mechanism behind it. In this project, the investigators plan to develop a fundamental understanding of the mechanism behind critical heat flux by exploring interfacial flow dynamics during flow boiling by using a combination of high-speed imaging and particle image velocimetry measurements. Using the data obtained, a mechanistic model will be developed to predict critical heat flux.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.