Heat Transfer Characteristics of a Fluid with Nano-Encapsulated Phase Change Materials

CBET-1133353 PI：Yagoobi总是需要在大小范围内加强换热。一般而言，增强是通过改进相应的表面来实现的。近年来，研究人员一直在探索通过向工质中添加相变材料(PCM)来改善工质的特性来强化换热。这项拟议的项目将研究与纳米级相变材料开发相关的基本任务。它还将通过理论、数值和实验研究，深入了解纳米级相变浆体(单一和多组分)的传输特性；因此，将了解与相变浆体流动相关的物理学。该项目将在两个相互关联的方向上进行。在第一种方法中，将使用一种保证其特性的高度控制的方法来生产新型的PCM纳米颗粒基流体，即长期稳定性和寿命。在第二个方向上，这些新型相变流体的流体力学和换热强化能力将在现实和实际相关的条件下，在中微通道流动和宏观封闭空间内的自由对流条件下进行评估。从科学的角度来看，这一建议将提高我们对纳米级相变材料悬浮液强化传热的认识。它将推出新型相变材料(单组分和多组分)，具有更宽的温度效率区间、更短的响应时间、更高的热容、更高的稳定性和更长的寿命，并充分表征高浓度下的流变行为。这些新型相变流体的流体力学特性和换热能力将通过在中微尺度通道和宏观尺度封闭空间中的流动的直接实验来阐明。相应的流场和温度场以及换热系数将通过数值模拟进行测量和预测，该数值模拟考虑了实际的流变行为和粘性耗散。这项研究还将揭示相变材料的热膨胀对强化封闭空间内自由对流换热的贡献程度，这一贡献预计将是显著的。这种基于PCM的新型流体的潜在应用可以产生巨大的影响，例如高效太阳能利用、电力电子、航天、暖通空调和空调、制造、运输、建筑以及化工、石油、炼油、塑料和橡胶工业。该项目将涉及本科生和研究生，包括多样化的学生。这项研究将被整合到拟议的教科书中，并被纳入两所大学教授的研究生课程中。将利用两所大学现有的课程，对芝加哥地区多元化的K12学生进行外联。

CBET-1133353PI:Yagoobi There is always a need to enhance heat transfer in large and small scales. Enhancements in general are achieved by improving the corresponding surfaces. In recent years, researchers have been exploring the enhancement of heat transfer by improving the characteristics of the working fluids via, for example, adding phase change materials (PCMs) to the working fluid. This proposed project will investigate the fundamental tasks pertinent to the development of nano-scale PCMs. It will also provide in-depth knowledge on the transport characteristics of nano-scale PCM slurries (single and multi components) via theoretical, numerical and experimental studies; thus, the physics associated with PCM slurry flows will be understood. The project will be conducted in two inter-related directions. In the first one, novel PCM nano-particle-based fluids will be produced using a method that guarantees a high degree of control of their characteristics, namely long-term stability and longevity. In the second direction, hydrodynamics and heat transfer enhancement capability of these novel PCM fluids will be evaluated under realistic and practically relevant conditions in meso- and micro-channel flows, and free convection flows within macro-scale enclosures. From a scientific perspective, this proposal will improve our understanding of the nano-scale PCM suspensions for heat transfer enhancement. It will introduce novel PCMs (single- and multi-component) with a wider temperature efficiency interval, a decreased response time, high heat capacity, improved stability, and longevity and fully characterized rheological behavior at high concentrations. The hydrodynamic characteristics and heat transfer capabilities of these novel PCM fluids will be elucidated using direct experiments with flows in meso- and micro-scale channels and macro-scale enclosures. The corresponding flow and temperature fields along with heat transfer coefficients will be measured and predicted using numerical simulations accounting for the realistic rheological behavior and viscous dissipation. This study will also reveal the extent of contribution of thermal expansion of PCMs toward enhancement of heat transfer in free convection flows within enclosures, which is expected to be significant. Examples of potential applications of such novel PCM-based fluids, where they can have enormous impact, include such fields as efficient solar energy utilization, power electronics, space, HVAC&R, manufacturing, transportation, construction as well as chemical, petroleum, refining, plastic, and rubber industry. The project will involve undergraduate and graduate students including students of diversity. The research will be integrated into a proposed textbook, and in a graduate course taught at both universities. Outreach to K12 students of diversity in the Chicago area will be conducted, leveraging existing programs at both universities.