Collaborative Research: A New Paradigm for Imperfectly-Mixed Chemical Reactions

合作研究：不完全混合化学反应的新范式

• 批准号: 1417145
• 负责人: David Benson
• 金额: $ 28.95万
• 依托单位: Colorado School of Mines
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-01 至 2018-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1417145&HistoricalAwards=false
• 关键词: Collaborative; Research; New; Paradigm; Imperfectly

Many of the chemicals that move within fluid undergo reactions. Often the reactions convert toxic compounds into harmless by-products. An example is the cleanup of gasoline that has leaked into a groundwater aquifer. It is very difficult, using current models, to predict the duration or rate of the reactions, primarily because of poor mixing of the reactants. This defines a significant theoretical and practical problem, because most current models of reactive transport in hydrologic systems are based on empirical adjustments to classical laws, which are built upon the flawed well-mixed assumption. In order to make reliable predictions in such systems, novel and improved methods are critical for the scientists and engineers, and ultimately decision makers, stakeholders, and policy developers working in fields such environmental contamination and remediation. However, the problem of mixing-limited reaction goes far beyond the hydrologic examples that motivated this proposal. Recent studies show that mixing-limited reactions play a dominant role in Earth-bound systems across a huge range of scales, including reactions in the atmosphere (e.g., ozone creation), in drinking-water aquifers (e.g., remediation of contaminants), in geologic basins (e.g., petroleum generation), and in magmas, hydrothermal areas, and ore bodies. This project will have application to many fields, including climate-change related atmospheric reactions, ecologic, and micro-biochemical systems. The investigators have developed new computer models that demonstrate the need for new paradigms of simulating reactions in imperfectly-mixed systems. First, the project will apply the theoretical approach of "time subordination" that accounts for random particle migration time to active reaction sites. Subordination has been successfully applied to simple systems, but it remains to be proven that it can be extended to more complicated reactions, geometries, and flow patterns. Second, the project will develop a random continuum method that tracks the growth of concentration disturbances. These disturbances include low concentration zones that are the key to slower reaction rates. Third, the project will build on the new computer models, shown to be correct, for the purpose of benchmarking theoretical results and facilitating large-scale reactive simulations. All approaches will be unified through detailed mathematical analysis and application to well-studied laboratory and field experiments.

在液体中运动的许多化学物质都会发生反应。通常，这些反应会将有毒化合物转化为无害的副产品。一个例子是清理泄漏到地下水含水层的汽油。使用目前的模型很难预测反应的持续时间或速率，主要是因为反应物混合不良。这定义了一个重大的理论和实践问题，因为目前大多数水文系统中的反应输运模型都是基于对经典定律的经验调整，而经典定律是建立在有缺陷的混合假设的基础上的。为了在这样的系统中做出可靠的预测，新颖和改进的方法对科学家和工程师以及最终在环境污染和修复等领域工作的决策者、利益相关者和政策制定者至关重要。然而，混合限制反应的问题远远超出了促使这一提议的水文学例子。最近的研究表明，混合限制反应在各种尺度的地球系统中发挥着主导作用，包括大气中的反应(例如臭氧的产生)、饮用水含水层中的反应(例如污染物的修复)、地质盆地中的反应(例如石油的产生)以及岩浆、热液地区和矿体中的反应。该项目将应用于许多领域，包括与气候变化有关的大气反应、生态和微型生化系统。研究人员开发了新的计算机模型，证明了在不完全混合的体系中模拟反应的新范例的必要性。首先，该项目将把解释随机粒子迁移时间的“时间从属”理论方法应用到活跃的反应地点。从属关系已被成功地应用于简单的体系，但它还有待证明，它可以扩展到更复杂的反应、几何形状和流动模式。其次，该项目将开发一种跟踪集中度扰动增长的随机连续方法。这些干扰包括低浓度区，这是减缓反应速度的关键。第三，该项目将建立在新的计算机模型的基础上，这些模型被证明是正确的，目的是对理论结果进行基准测试，并促进大规模的反应模拟。所有方法将通过详细的数学分析和应用于经过充分研究的实验室和现场实验而统一。