CAREER: Influence of electric fields on liquid-to-solid phase change associated with clathrate hydrate formation

职业：电场诱导水合物形成的基本机制研究笼形水合物是一种水基晶体固体，由捕获在水分子晶格中的客体分子（甲烷、二氧化碳、四氢呋喃、环戊烷等）组成。水合物可以成为许多能源-水相关领域的新应用基础，如天然气运输、海水淡化和碳封存。与水合物形成相关的一个重大挑战是水合物开始形成（成核）之前的漫长等待时间，可能需要数小时至数天。最近的研究表明，施加的电压可以显著加速水合物的形成，并将等待时间减少一百倍或更多。这种电成核概念可以实现上述应用中水合物的快速和可控合成，所有这些应用都需要快速形成水合物。本项目是电场诱导水合物形成机制的基础性研究。分析了电荷、电流、传热和表面化学对三种水合物形成的影响。总的来说，这项工作将在水合物和液固相变领域产生开创性的贡献。该项目的结果有可能完全消除水合物形成的延迟，并实现“按需”水合物形成。这项研究的结果将整合到教育活动中，其中包括开发一门关于相变传热的研究生课程，并为本科生和代表性不足的少数民族提供研究机会。本课题研究了三种水合物的电成核。在第一组研究中，将分析两种不混相液体的水合物形成。环戊烷水合物的形成将通过实验和分析建模来量化电场和界面电荷对水合物成核的作用。在第二组研究中，将分析可混相液体的水合物形成。将分析四氢呋喃水合物的形成，以了解电流和由此产生的气泡对成核的影响。第三组研究将分析甲烷水合物的电成核，其中水合物在高压下在液气界面成核。该项目包括核测量实验、分析多物理场建模和相关发展。微流控细胞将被制造出来，以获得电成核的统计上有意义的估计。该项目的具体成果包括电成核速率的测量，以及对各种水合物形成的物理基础的理解。这个项目将强调电场在从根本上改变成核性质的作用，从随机到确定性。总的来说，本研究将使我们能够深入了解电现象对与水合物形成相关的微/中尺度热流体现象的影响。

CAREER: Investigation of the fundamental mechanisms underlying electric field-induced formation of hydratesClathrate hydrates are water-based crystalline solids consisting of a guest molecule (methane, carbon dioxide, tetrahydrofuran, cyclopentane and others) trapped in a lattice of water molecules. Hydrates can be the basis of novel applications in many energy-water related areas such as natural gas transportation, desalination and carbon sequestration. A significant challenge associated with hydrate formation is the long wait time before hydrates start forming (nucleate), which can range from hours to days. Recent studies indicate that applied electrical voltages can significantly accelerate hydrate formation, and reduce the wait time by a factor of hundred or more. This electro-nucleation concept can enable rapid and controlled synthesis of hydrates for the above applications, all of which require rapid hydrate formation. This project is a fundamental study of the mechanisms underlying electric-field induced formation of hydrates. The influence of electric charge, current flow, heat transfer and surface chemistry on hydrate formation will be analyzed for three kinds of hydrates. Overall, this work will lead to seminal contributions in the fields of hydrates and liquid-to-solid phase change. The results of this project have the potential of completely eliminating the delay in hydrate formation, and enabling "on-demand" hydrate formation. Results from this research will be integrated into educational activities, which include the development of a graduate level course on Phase Change Heat Transfer and research opportunities for undergraduates and under-represented minorities. This project studies the electro-nucleation of three kinds of hydrates. In the first set of studies, hydrate formation from two immiscible liquids will be analyzed. Cyclopentane hydrate formation will be studied via experiments and analytical modeling to quantify the role of electric fields and interfacial charge on hydrate nucleation. In the second set of studies, hydrate formation from miscible liquids will be analyzed. Tetrahydrofuran hydrate formation will be analyzed to understand the influence of electric current and the resultant bubble generation on nucleation. The third set of studies will analyze electro-nucleation of methane hydrates, wherein hydrates nucleate at a liquid-gas interface at elevated pressures. This project includes nucleation-measurement experiments, analytical multiphysics modeling, and correlation development. Microfluidic cells will be fabricated to obtain statistically meaningful estimates of electro-nucleation. Specific outcomes of this project include measurements of electro-nucleation rates, and an understanding of the physics underlying the formation of various hydrates. This project will highlight the role of electric fields in fundamentally changing the nature of nucleation from stochastic to deterministic. Overall, this research will enable an in depth understanding of the influence of electrical phenomena on micro/mesoscale thermo-fluidic phenomena associated with hydrate formation.