Coupling Tribocharging and Hydrodynamics in Fliuidized Beds

CBET -1601986 PI：Sundaresan，Sankaran摩擦充电是指两种材料之间的电荷交换，使彼此机械接触。 在许多涉及悬浮在气体中的颗粒流动的情况下都可以观察到这种现象。 一个工业上重要的例子是流化床化学反应器中的摩擦充电。 在这种反应器中，气体以如此高的速率流过颗粒床，使得颗粒变得“流化”，并且颗粒和气体表现为流体混合物。 该项目旨在了解摩擦荷电如何影响气体-颗粒悬浮液的流体动力学。 将开发模型来解释和预测摩擦充电的动态和气体颗粒悬浮液的流体动力学如何受到材料特性，湿度和颗粒尺寸的影响。 这项研究将是第一项专门针对摩擦荷电和流化流体力学之间耦合的研究。 结果将是有用的，在广泛的工业过程中，涉及气-固悬浮液，因为摩擦充电可以创建显着的危险，降低工艺效率。 该项目将为不同学术水平的学生提供参与研究的机会，包括参加普林斯顿大学夏季实验室学习计划的高中生。该项目的目标是开发和验证一个计算模型，该模型考虑了流体-颗粒流动系统中的摩擦充电和静电力，以了解静电如何影响流体力学，并了解这些系统中的瞬时充电速率。 该模型将使用摩擦带电的有效功函数，该功函数捕获由于接触颗粒的材料差异、接触颗粒的总电荷差异、接触颗粒的尺寸差异和湿度引起的电荷转移。 有效的功函数将被纳入一个模型，该模型结合了离散元方法，用于解决颗粒接触与计算流体动力学，用于解决更大规模的流动。 模型参数将使用振动床实验进行校准。 然后，该模型的预测流化床动力学将测试对实验中，颗粒材料，尺寸，湿度和流化床的壁材料系统地变化。 研究结果将提供有用的信息，工业从业人员，以改善涉及颗粒物料的过程。

CBET - 1601986PI: Sundaresan, SankaranTribocharging refers to the exchange of electric charge between two materials that make mechanical contact with each other. It is observed in many situations involving flows of particles suspended in a gas. One industrially important example is tribocharging in a fluidized bed chemical reactor. In this kind of reactor, gas flows through a bed of particles at such high rates that the particles become "fluidized," and the particles and gas behave as a fluid mixture. This project seeks to understand how tribocharging affects the fluid dynamics of gas-particle suspensions. Models will be developed to explain and predict how the dynamics of tribocharging and hydrodynamics of gas-particle suspensions are affected by material characteristics, humidity, and particle size. The research will be the first study that focuses specifically on the coupling between tribocharging and fluidization hydrodynamics. The results will be useful in a wide range of industrial processes involving gas-solid suspensions, because tribocharging can create significant hazards and reduce process efficiencies. The project will provide opportunities for students at various academic levels to participate in research, including high-school students who participate in Princeton's summer Laboratory Learning Program.The goals of the project are to develop and validate a computational model that accounts for tribocharging and electrostatic forces in fluid-particle flow systems, to understand how electrostatics affect hydrodynamics, and to understand the transient rate of charging in these systems. The model will use an effective work function for triboelectric charging that captures charge transfer owing to differences in material of contacting particles, differences in overall charge of contacting particles, differences in sizes of the contacting particles and humidity. The effective work function will be incorporated into a model that combines a discrete element method for resolving particle contacts with computational fluid dynamics for resolving larger scales of the flow. Model parameters will be calibrated using vibrated bed experiments. Then, the model's predictions of fluidized bed dynamics will be tested against experiments in which particle material, size, humidity and the wall material of the fluidized bed are systematically varied. Results of the study will provide useful information for industrial practitioners to improve processes involving granular materials.