Theoretical Studies of Near-Critical Fluids in Dilute Porous Media

稀多孔介质中近临界流体的理论研究

• 批准号: 9624090
• 负责人: Andrea Liu
• 金额: $ 32.95万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-04-01 至 2000-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9624090&HistoricalAwards=false
• 关键词: Theoretical; Studies; Near; Critical; Fluids

Andrea Liu is supported by a Faculty Early Career Development Award from the Theoretical and Computational Chemistry Program to study equilibrium phase behavior and diffusive transport in near-critical fluids, such as vapor-liquid systems or binary liquid mixtures, confined in dilute porous media such as silica gels. In general, the behavior of a near-critical fluid in a porous medium is an extremely difficult theoretical problem, because the surface of the medium strongly prefers one phase of the fluid and because the structure of the medium is highly disordered. The approach used by Liu focuses on the strong interaction between the fluid and the surface; previous theoretical work has assumed that the interaction is weak and that disorder is the dominant factor. The keystone of the proposal is a model of the confining medium as a simple periodic network of cylindrical strands, which Liu has solved within the mean-field approximation. The proposed work builds on this basic model by using a coordinated combination of analytic and numerical techniques to investigate the effects of critical fluctuations and long-wavelength disorder in the gel structure, as well as the nonequilibrium behavior. This approach represents the best hope of isolating the effects of surface interactions and of disorder in the geometry of the medium in order to determine their relative importance for equilibrium and nonequilibrium behavior. The proposed education plan is centered around effective scientific communication. The objectives are to demystify science for non-majors and to convince them that chemistry is an important and interesting part of daily life, and to teach majors and graduate students how to communicate their work more effectively. Nearly critical fluids in dilute porous media, such as those studied by Liu, are models for more general multiphase fluids in more realistic porous media. Applications that are of industrial importance range from catalysis in porous beds, to storage of liquid wastes and liquid fuels in porous glasses, to the extraction of liquids such as oil from porous media like sandstone. An improved theoretical understanding of transport in porous media could have a significant impact in several of these strategic areas.

Andrea Liu获得了理论和计算化学计划颁发的学院早期职业发展奖，该奖项旨在研究近临界流体(如汽液体系或二元液体混合物)中的平衡相行为和扩散传输，这些流体受限于稀疏型多孔介质(如硅胶)。一般来说，近临界流体在多孔介质中的行为是一个极其困难的理论问题，因为介质的表面强烈地倾向于流体的一相，而且介质的结构是高度无序的。刘使用的方法侧重于流体和表面之间的强相互作用；以前的理论工作假设相互作用很弱，无序是主导因素。该提议的重点是将约束介质模型描述为简单的圆柱状周期性网络，刘在平均场近似下求解了该模型。所提出的工作建立在这一基本模型的基础上，使用解析和数值技术的协调组合来研究凝胶结构中的临界涨落和长波长无序的影响，以及非平衡行为。这种方法代表了分离表面相互作用和介质几何中无序的影响的最大希望，以便确定它们对平衡和非平衡行为的相对重要性。拟议的教育计划以有效的科学交流为中心。其目的是为非专业学生揭开科学的神秘面纱，让他们相信化学是日常生活中重要而有趣的一部分，并教会专业学生和研究生如何更有效地沟通他们的工作。稀薄多孔介质中的近临界流体，如刘所研究的那些，是更真实的多孔介质中更一般的多相流体的模型。具有工业重要性的应用范围从多孔床中的催化，到在多孔玻璃中存储液体废物和液体燃料，再到从砂岩等多孔介质中提取液体(如石油)。更好地从理论上理解多孔介质中的传输可能会对这些战略领域中的一些领域产生重大影响。