GOALI: Population Balance Modeling: Fundamental Closures and Experimental Validation

在自然界中，雪崩和山体滑坡中固体颗粒的流动会导致相当毁灭性的影响。在工业加工中，固体颗粒的流动是药品、石油和天然气、化学品和农产品生产所固有的。为了避免类似的不利影响，如工业事故和生产力损失，预测和控制这些颗粒系统的流动是很重要的。然而，人们对固体颗粒的流动知之甚少，也不容易建立模型。液体流动模型是工程的一个基本要素，它来源于基本的物理原理，而目前的固体颗粒流动模型依赖于可调节的参数，是经验的，并包含了一些总体上的简化。这个研究项目使用计算机模拟和最先进的实验来开发和验证基于可测量量的固体颗粒流动的理论模型。此外，这项工作支持代表性不足的群体的参与，培训初级研究人员和学生，以及学生参与工业-学术研究伙伴关系。该项目的结果将通过博客文章和Twitter账户与公众沟通。本项目的重点是可靠地预测固体在流动气体的向上运动下流化时的质量流速。当应用于同一系统时，粒子夹带速率常数的现有经验相关性可能会变化许多数量级。目前的模型主要受限于经验主义和发展到一个非常特殊的情况。为了发展对流化颗粒系统的预测性理解，本研究正在推导基于种群和动力学理论平衡的连续统理论的闭合。由此产生的内聚粒子流模型只需要可测量的物理量作为输入。新的连续体框架被应用于湿度诱导团聚的情况。将离散元数值模拟与非侵入式阴影实验相结合，对新理论进行了验证。这项工作的一个独特方面是发展了一种新的微观（粒子-粒子）内聚模型，该模型推动了宏观（连续体）理论的闭合。

In nature, the flow of solid particles in avalanches and landslides can lead to quite devastating effects. In industrial processing, the flow of solid particles is inherent to the production of pharmaceuticals, oil and gas, chemicals, and agricultural products. To avoid comparable adverse effects, such as industrial accidents and lost productivity, it is important to predict and control the flow of these granular systems. However, the flow of solid particles is poorly understood and not easily modeled. Whereas models of liquid flow are a basic tenant of engineering and derived from basic physical principles, current models of solid particle flow rely on adjustable parameters, are empirical, and incorporate a number of gross simplifications. This research project uses computer simulations and state-of-the-art experiments to develop and validate theoretical models of flows of solid particles that are based on measurable quantities. In addition, this work supports the involvement of underrepresented groups, the training of junior researchers and students, and the involvement of students in an industrial-academic research partnership. Results from the project will be communicated to the general public via blog posts and a Twitter account.This project is focusing on the reliable prediction of the mass flow rate of solids when they are fluidized by the upward motion of a flowing gas. Existing empirical correlations for particle entrainment rate constants may vary by many orders of magnitude when applied to the same system. Current models are primarily limited by empiricism and development to a very particular situation. To develop a predictive understanding of fluidized granular systems, this research is deriving a closure for the continuum theory that is based on population and kinetic theory balances. The resulting model for cohesive-particle flows will require only measurable, physical quantities as inputs. The new continuum framework is being applied to the case of humidity-induced agglomeration. Numerical modeling with discrete element method simulations is being combined with non-intrusive shadowgraphy experiments to validate the new theory. A unique aspect of the work is the development of a novel microscopic (particle-particle) cohesion model that drives the closure of the macroscopic (continuum) theory.