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Magnetic Resonance Imaging and Modeling of Gas and Particle Flow in Fluidized Beds

流化床中气体和颗粒流的磁共振成像和建模

基本信息

批准号：
2024346
负责人：
Christopher Boyce
金额：
$ 36.9万
依托单位：
Columbia University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2020
资助国家：
美国
起止时间：
2020-11-15 至 2023-10-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2024346&HistoricalAwards=false
关键词：
Magnetic Resonance Imaging Modeling Gas

项目摘要

Collections of granular (i.e. sand-like) particles normally behave like a solid; however, flowing air up through these particles can make them behave like a bubbling liquid, as observed in industrial process units called “fluidized beds”. Fluidized beds are used in the energy, pharmaceuticals and food industries and in emerging industries for carbon capture and sequestration. Magnetic resonance imaging (MRI) is used to see structure and motion within the human body non-invasively, but it can also be used to image dynamics inside other 3D opaque systems. This project will use MRI to study the motion of both the gas and the sand-like particles surrounding bubbles in fluidized beds and will use this knowledge to improve scientific understanding of the systems. In turn, this understanding can be tailored to enable environmental technologies. Beyond creating scientific and technological insights, this project will benefit the education of students from the high school to the PhD level. High school students from neighboring Harlem and Bronx communities will conduct laboratory research under the supervision of graduate students to provide hands-on experience in uncovering the amazing physics of liquid-like flow of particles and its widespread applications. The high school students will create videos of the bubbly flows to improve their understanding of the science while educating classmates and the general public on the fascinating nature of bubbly flows.Fluidization is the process of suspending granular particles by upward gas flow, transitioning from a solid-like state to a fluid-like state. Voids or “bubbles” of gas rise through fluidized particles, inducing positive effects such as particle mixing as well as negative effects such as diminished gas-solid contact. Thus, understanding the detailed flow physics of gas and particles around bubbles is critical to optimizing a number of technologies as well as developing new tailorable processes. These bubbles are much different from those in conventional liquids, since there is no surface tension separating the bubble and particulate phases and gas passes freely between the bubbles and the surrounding interstices between particles. The inability to “see” the dynamics within 3D opaque systems has left the scientific knowledge of flow around these bubbles largely theoretical, with significant assumptions made in analytical and computational models. Without robust measurements of gas and particle dynamics surrounding bubbles, the accuracy of various assumptions has gone largely unassessed. Recently, the research team for this project has demonstrated that MRI can be used to measure gas and particle dynamics in bubbling fluidized beds. Despite the low temporal resolution of MRI, the team has shown that by synchronizing MRI measurements and reproducibly injected bubbles, effectively instantaneous dynamics around a single bubble can be imaged in 3D. Here, the PI intends to image the gas and particle dynamics surrounding bubbles while varying critical flow conditions to generate insights on how these conditions affect dynamics. The quantitative measurements will be used to assess the validity and areas for improvement in analytical and computational models.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.

粒状（即沙状）颗粒的集合通常表现得像固体;然而，向上流过这些颗粒的空气可以使它们表现得像起泡液体，如在称为“流化床”的工业过程单元中所观察到的。流化床用于能源、制药和食品行业以及新兴行业的碳捕获和封存。磁共振成像（MRI）用于非侵入性地查看人体内的结构和运动，但它也可以用于其他3D不透明系统内的动态成像。该项目将使用MRI来研究流化床中气泡周围的气体和沙状颗粒的运动，并将利用这些知识来提高对系统的科学理解。反过来，这种理解可以被定制，以实现环境技术。除了创造科学和技术的见解，该项目将有利于学生从高中到博士水平的教育。来自邻近的哈莱姆和布朗克斯社区的高中生将在研究生的监督下进行实验室研究，以提供实践经验，揭示粒子液体流动的惊人物理学及其广泛应用。高中生将制作气泡流的视频，以提高他们对科学的理解，同时教育同学和公众对气泡流的迷人本质。流化是通过向上的气流悬浮颗粒，从固体状态转变为流体状态的过程。气体的空隙或“气泡”通过流化颗粒上升，引起诸如颗粒混合的正面效应以及诸如减少气-固接触的负面效应。因此，了解气泡周围气体和颗粒的详细流动物理特性对于优化许多技术以及开发新的可定制工艺至关重要。这些气泡与常规液体中的气泡有很大不同，因为没有表面张力将气泡和颗粒相分离，并且气体在气泡和颗粒之间的周围间隙之间自由通过。由于无法“看到”3D不透明系统中的动态，这些气泡周围流动的科学知识在很大程度上是理论上的，在分析和计算模型中做出了重要的假设。由于没有对气泡周围的气体和粒子动力学进行可靠的测量，各种假设的准确性在很大程度上没有得到评估。最近，该项目的研究小组已经证明，MRI可用于测量鼓泡流化床中的气体和颗粒动力学。尽管MRI的时间分辨率很低，但该团队已经证明，通过同步MRI测量和可重复注入的气泡，可以在3D中对单个气泡周围的有效瞬时动态进行成像。在这里，PI打算在改变临界流动条件的同时对气泡周围的气体和颗粒动态进行成像，以了解这些条件如何影响动态。定量测量将用于评估分析和计算模型的有效性和改进领域。该奖项反映了NSF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。