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Fuel Cells
Research in fuel cells in the Department of Mechanical Engineering is currently focused on Polymer Electrolyte Membrane (PEM) fuel cells and Direct Methanol Fuel Cells (DMFC). PEMFC research includes reactant gas transport modeling and measurement, water management, in-house fabrication and testing, membrane durability studies, and computational fluid dynamics. DFMC research involves the incorporation of metal foams to provide multi-functionality. A project to research, build and deploy a fuel cell powered transit vehicle in Delaware has also commenced.
Our research is funded by federal and state sources, and industry. Companies involved in fuel cell component manufacture like WL Gore and Associates, Dupont, and Ion Power, as well as corporations involved with the production and transport of hydrogen like Air Liquide, and Air Products are located in close proximity to the University of Delaware. |
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Reactant Gas Transport
We have investigated the relative importance of convective bypass through the gas diffusion layer of single-serpentine channels to bring fresh reactant to the catalyst layer and remove product water. Our analytical study has shown the convective bypass can be the dominant mechanism in cells of large size, such as those used in automotive stacks. Secondary flows created by channel bypass have been measured by particle image velocimetry in a model PEM cell. |
Water Management
The by-product of a hydrogen fuel cell reaction is pure water. Under normal operating conditions water emerges from the fuel cell in vapor form, but under conditions of high current draw large water production can lead to condensation and flooding within the cell. At the same time, adequate PEM hydration must be maintained to ensure good protonic conductivity. This problem of conflicting requirements is termed water management. For this research, we have fabricated a unique, transparent operational PEM cell. We are varying component properties, cell design, and operating conditions to visually characterize flooding and develop water management techniques that will help prevent it.
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Durability
During operation, the fuel cell membrane absorbs water and swells causing a volume change. Since the membrane is confined in the fuel cell assembly, the swelling can lead to large mechanical stresses. Thus, it is critical to measure the volume change as a function of temperature and humidity. We have developed a unique capability to measure the mechanical properties—including the volume change—of the fuel cell membrane, as a function of temperature and humidity. The equipment is a combination of an environmental chamber and a strength-test machine. The results obtained from the experiments are used in finite element simulations where the mechanical stresses are determined. This will eventually lead to a lifetime prediction of the polymer fuel cell assembly.
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Computational Fluid Dynamics for PEM Fuel Cells
Computational models are being developed to better understand the performance of PEM fuel cells, such as pressure loss and thermal effects in the flow channels, species transport through porous gas diffusion layers, and water management on the cathode side. We are developing a quantitative modeling tool using the lattice Boltzmann (LB) approach. The LB approach is a kinetic approach offering flexibility and reliability in treating complex multiphase flows encountered in fuel cells. We have developed single-phase flow models through the flow channel and the porous gas diffusion layer. Our goal is to extend these models to multiphase flow and eventually develop a predictive tool for fluid and species transport in fuel cells. |
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FC-powered Transit Vehicle
Under sponsorship of the Federal Transit Administration, we are pursuing a project to research, build and deploy the first fuel cell powered vehicle in Delaware. A consortium has been formed with a leading fuel cell manufacturer, chassis provider, and integrator for this purpose. The project involves fundamental research for improving the performance and efficiency of the stack, design and configuration studies of the fuel cell and balance of plant, hydrogen storage system, batteries for hybrid operation, control systems, and sensors for data collection. In collaboration with the Department of Civil Engineering, we will also conduct studies of maintainability, reliability and serviceability.
Which faculty members are doing research in this area? Take a look at the Faculty Research Matrix to find out. |
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