Multiphase flow modelling of chemical processes

多相流在化工和矿物加工过程中无处不在。例如：(a)沥青提取，在沥青中，水、砂和空气在水力输送管线或旋转滚筒中接触，然后在分离容器和浮选装置中进行处理；(b)精馏塔和(c)流化床。然而，对这些流程的基本理解是非常困难的，这导致了为实现简单的设计过程而调用的简化假设。理想的蒸馏塔盘、搅拌均匀的混合槽等例子在化学工程中是很常见的。这些简化虽然允许开发简单的设计程序，但往往限制了设计师将操作从实验规模扩展到中试规模再到全工厂规模的能力。幸运的是，强大的计算机和最新的计算算法使计算流体动力学的发展，特别是多相流的直接模拟成为可能。我的主要贡献是开发下一代高效算法，以及将CFD应用于能源领域遇到的许多实际问题。在下一阶段的研究中，我计划继续研究多相流，以处理固体-流体系统和流体-流体系统。重点将放在复杂几何形状的两相混合物的流动上，比如聚合物加工过程中遇到的双螺杆挤出机、Lab-on-A-Chipo设备中遇到的微流体装置、燃料电池堆中的流动。

Multiphase flows are ubiquitous in chemical and mineral processing operations. Examples are: (a) bitumen extraction where in bitumen, water, sand and air are contacted either in the hydro transport lines or in rotating tumblers, followed by processing in separation vessels and flotation devices, (b) distillation columns and (c) fluidized beds. Yet fundamental understanding of these flows is very difficult to develop resulting in simplifying assumptions that are invoked to enable simple design procedures. Examples such as the ideal distillation tray, well stirred mixing tank with homogenous compositions are very common in chemical engineering. These simplifications, while allowing simple design procedures to be developed, often limit the ability of designers to scale up an operation from bench scale to pilot scale to full plant scale. Fortunately powerful computers and recent computational algorithms are enabling development of computational fluid dynamics and in particular direct simulation of multiphase flows. My main contributions have been both in the development of next generation, efficient algorithms as well as applications of CFD to many practical problems encountered in the energy sector. During the next period of research under this Discovery Grant, I plan to continue the study of multiphase flows for handling both solid-fluid systems and fluid-fluid systems . The focus will be on flow of two phase mixtures in complex geometries like the twin-screw extruders encountered polymer processing, micro fluidic devices encountered in Lab-on-A-Chipo devices, flow in fuel cell stacks.