EAGER: Experimental Methods and Measurements of Anomalous Properties of Supercritical Fluids and their Mixtures

超临界条件下的流体不再存在不同的液态和气相，是强化热传输和有效的热控制和管理的良好候选者。超临界热交换器是太阳能直接转换、发电、空间系统热管理等领域很有前途的解决方案。然而，由于缺乏对异常行为的了解，超临界传热的研究一直受到限制，这些异常行为的特征是临界点附近区域的热物性变化很大，以及与之相关的热振荡和涨落。这个急切的项目将发展测量异常区域超临界性质的实验能力，以提高对超临界流体及其在传热应用中的性能的基本了解。这个急切的项目试图探索：(I)利用反常行为来实现强化传热，(Ii)利用超临界压力的微小变化来进行热管理和控制，以及(Iii)改变超临界流体混合物的临界温度来调节热量散失的温度。该项目的任务是获得二氧化碳与Ar和R134a混合物的临界性质的实验数据，并进行自然对流实验，以演示异常区域温度和压力的影响。如果成功，这个急切的项目可以为在极端温度下使用超临界流体混合物散热奠定基础，并使其能够应用于太阳能热能和发电系统。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Fluids under supercritical conditions, where distinct liquid and gas phases no longer exist, are good candidates for enhanced thermal transport and effective thermal control and management. Supercritical heat exchangers are promising solutions for direct solar energy conversion, power generation, thermal management of space systems, to name a few. However, research on supercritical heat transfer has been limited because of the lack of understanding of anomalous behaviors, characterized by large variations in thermophysical properties in a region around the critical point, and the associated thermal oscillations and fluctuations. This EAGER project will develop experimental capabilities to measure supercritical properties in the anomalous region to improve the fundamental understanding of supercritical fluids and their performance in heat transfer applications.This EAGER project seeks to explore: (i) the use of anomalous behavior to achieve enhanced heat transfer, (ii) thermal management and control using a small variation in supercritical pressure, and (iii) change in critical temperature of supercritical fluid mixture to tune the temperature at which the heat dissipates. The project tasks are to obtain experimental data on critical properties for mixtures of CO2 with Ar and R134a and conduct natural convection experiments to demonstrate the effect of temperature and pressure in the anomalous region. If successful, this EAGER project could build the foundation of using supercritical fluid mixtures for heat dissipation at extreme temperatures and enable applications in solar thermal and power generation systems.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.