Collaborative Research: Multiscale study of oscillating flow and multiphase heat transfer in porous media

在我们不断发展的能源格局中，最大限度地提高能源技术的效率，了解化石燃料开采和碳储存的影响至关重要。这方面的核心技术——地下修复、地热能系统、电池、水力压裂等——是由通过多孔介质的复杂流动控制的，这一点目前还没有得到很好的理解。多孔介质具有多种不同大小的流体流过固体材料的迂回路径。流动可以是单相（液/气）或多相，可以在恒温或传热的情况下发生。流动可以是单向的，也可以是振荡的。当所有这些结合在一起时，就会产生非线性效应，这可能会改善系统的行为，也可能会对性能产生负面影响，这取决于这些效应是如何传播和理解的。这项工作的主要目的是通过实验研究多孔介质中的振荡和多相流，然后开发一种数值方法，可以用来进一步了解基本行为，从而提高能源效率，降低经济成本和环境影响。虽然多孔介质流动听起来很深奥，但它在许多日常应用中都存在（冲咖啡等）。因此，这个项目非常适合大学前的推广，与之相关的几个主题将用于吸引来自K-12教室的代表性不足的学生。此外，该项目将通过本科设计项目的跨学院教育合作来促进STEM教育，并将为大学预科教室创建有关多孔介质流动的示范单元。本研究将结合实验和数值技术来描述物理多孔结构、流动/传热边界层的影响（包括振荡和非振荡的比较）以及材料和制造工艺对润湿性的影响。实验上，自然发生的和工程多孔介质将被扫描、分析，并在数据库中进行分类，并且还将设计和开发一个实验平台，使用橡树岭国家实验室的中子成像设备研究多孔介质内部的原位振荡和多相输运现象。本实验工作将与数值模拟相结合，通过并行开发多相离散玻尔兹曼方法模型和混合离散/晶格玻尔兹曼方法模型来捕捉动力学行为和多尺度相互作用，以阐明振荡多相热流体现象和流固相互作用的基本行为。在这个项目中发展的知识，反过来，将用于改进各种能源应用中的多孔结构的设计，包括聚光太阳能发电厂的储热，岩石结构中的碳保留和燃料电池。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

In our evolving energy landscape, it is crucial to maximize the efficiency of energy technologies and understand the impact of fossil fuel extraction and carbon storage. Technologies that are central to this - subsurface remediation, geothermal energy systems, batteries, fracking, etc. - are governed by complicated flow through porous media, which is not currently well understood. A porous medium has multiple, convoluted pathways of various sizes for fluid flow through an otherwise solid material. The flows can be single phase (liquid/gas) or multiphase, and can occur at constant temperature or with heat transfer. The flow can occur in a single direction, or oscillate. When all of these are combined, nonlinear effects can result, which could improve the behavior of a system or negatively impact performance, depending on how the effects are propagated and understood. The major objective of this work is to experimentally study oscillating and multiphase flows in porous media, and then develop a numerical approach that can be used to gain further insight into the fundamental behavior, thereby improving energy efficiency, and lowering both economic costs and environmental impacts. Although porous media flow sounds esoteric, it occurs in many daily applications (brewing coffee, etc.). Therefore, this project is well suited for pre-college outreach, and several topics related to it will be used to engage underrepresented students from K-12 classrooms. In addition, this project will promote STEM education via an inter-college educational collaboration for undergraduate design projects, and demonstration units about porous media flows will be created for pre-college classrooms.This research will combine experimental and numerical techniques to describe the effects of the physical porous structure, the flow/heat transfer boundary layer (including a comparison between oscillation and non-oscillation) and the variations in wettability from materials and manufacturing process. Experimentally, naturally-occurring and engineered porous media will be scanned, analyzed, and catalogued in a database, and an experimental platform will also be designed and developed to study in situ oscillating and multiphase transport phenomena inside porous media using the Neutron Imaging Facility at Oak Ridge National Lab. This experimental work will be coupled with numerical simulations through parallel development of a multiphase discrete Boltzmann method model and a hybrid discrete/lattice Boltzmann method model to capture kinetic behaviors and multiscale interactions, in order to elucidate the fundamental behavior of oscillating multiphase thermofluidic phenomena and fluid-solid interactions. The knowledge developed in this project will, in turn, be used to improve the design of porous structures in a variety of energy applications, including thermal storage in concentrated solar power plants, carbon retention in rock structures, and fuel cells.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.