Dynamics and Chemical - Mechanical Coupling in PEM Fuel Cells

知识价值：燃料电池已被美国政府确定为氢经济的重要组成部分，以减少对化石燃料的需求并改善环境。聚合物电解质膜（PEM）燃料电池在低温下工作，最适合汽车应用。PEM燃料电池必须在反映驾驶条件的广泛环境和负载条件下具有快速的动态响应。本项目所涉及的燃料电池动力学和控制的基本原理对于使PEM燃料成为汽车应用中经济可行的技术是必要的。PI开发了一种“理想化的”PEM燃料电池，用于检查燃料电池的动力学。模型燃料电池是一个一维差动反应器，在阳极和阴极具有均匀的、独立可控的、明确的气相组成。模型燃料电池可以被认为是两个搅拌槽反应器（STR）通过膜耦合，因此命名为STR PEM燃料电池。STR PEM燃料电池的一维结构极大地简化了对系统参数变化的动态响应，是对大型复杂燃料电池反应堆系统性能进行标化和建模的基本微分元。对STR PEM燃料电池的初步研究表明，聚合物电解质膜是水的储存库，膜的阻力和机械性能取决于膜中的水存量。PEM燃料电池运行参数的变化，如外部负载阻力或燃料电池温度，改变了产水和除水之间的平衡，改变了膜中的膜水活性。在广泛的操作条件下对PEM燃料电池动力学进行广泛的参数化研究。聚合物电解质膜的化学和机械性能的动态测量将补充燃料电池的研究。更广泛的影响：燃料电池作为“氢经济”商业发展中最有前途的技术之一，引起了人们的极大兴趣，这是出于环境和政治原因的高度优先考虑。本课题的研究成果对提高PEM燃料电池的高效、稳健的可操作性和可控制性具有重要意义。该计划解决了与水管理动态和操作条件变化（包括可变负载）相关的基本问题。质子交换膜燃料电池的动力学问题以前还没有得到解决。从这里概述的工作中开发的数据和模型将作为PEM燃料电池系统工程的基础。

Intellectual Merit: Fuel cells have been identified by the US government as an essential element of the hydrogen economy to reduce demand for fossil fuels and improve the environment. Polymer electrolyte membrane (PEM) fuel cells operate at low temperatures and are best suited for automotive applications. PEM fuel cells must have a rapid dynamic response over a broad range of environmental and load conditions reflecting driving conditions. The fundamentals of fuel cell dynamics and control addressed in this project are necessary to make PEM fuel an economically viable technology for automotive applications.An "idealized" PEM fuel cell was developed by the PI to examine fuel cell dynamics. The model fuel cell is a one-dimensional differential reactor with uniform, independently controllable, well-defined gas phase compositions at the anode and cathode. The model fuel cell can be thought of as two stirred tank reactors (STR) coupled by a membrane, hence the name the STR PEM fuel cell. The one-dimensional structure of the STR PEM fuel cell greatly simplifies the dynamic response to changes in system parameters, and is the basic differential element for scaling and modeling the performance of larger complex fuel cell reactor systems. Preliminary studies with the STR PEM fuel cell have shown the polymer electrolyte membrane is a reservoir for water, and the membrane resistance and mechanical properties depends on the water inventory in the membrane. Changes in the operating parameters of the PEM fuel cell, such as the external load resistance or the fuel cell temperature, alter the balance between water production and water removal changing the membrane water activity in the membrane. Extensive parametric studies of PEM fuel cell dynamics over a broad range of operating conditions will be pursued. Dynamic measurements of the chemical and mechanical properties of polymer electrolyte membranes will complement the fuel cell studies. Broader Impacts: Fuel cells are of great interest as one of the most promising technologies for the commercial development of the "hydrogen economy," which is of high priority for environmental and political reasons. The research outlined in this project could advance the efficient and robust operability and control of PEM fuel cells. The program addresses fundamental issues associated with the dynamics of water management and changes in operating conditions including variable load. The dynamics of PEM fuel cells have not been previously addressed. The data and models developed from the work outlined here will serve as a basis for systems engineering of PEM fuel cell systems.