Transport Modeling Working Group
The Transport Modeling Working Group meets twice per year to exchange information, create synergies, share experimental and computational results, and collaboratively develop methodologies for and understanding of transport phenomena in polymer electrolyte fuel cell stacks. Its members include principle investigators and supporting personnel from transport-related projects funded by the U.S. Department of Energy (DOE). Learn more about DOE research activities can be found in the Multi-Year Research, Development, and Demonstration Plan.
Fuel cell operation relies on effective mass transport of species through individual components and across the interfaces between components. Among these species are hydrogen, oxygen, water, protons, and electrons. Transport behavior is a function of operating conditions and component properties such as microstructure and surface properties. Understanding and optimizing the controlling transport phenomena are critical to the efficient and cost-effective operation of polymer electrolyte fuel cells. A better understanding of mass transport in the fuel cell, especially of water, has the potential to lead to improved designs and more efficient systems.
DOE has established numerous performance targets for fuel cells for stationary and transportation applications. An understanding of how fuel cells operate is needed to optimize fuel cell performance and achieve performance targets. Mathematical modeling is ideally suited for this analysis because fuel cells are difficult to probe in detail through in situ experimentation. For example, while ex situ diagnostics can yield fuel cell component properties, and in situ testing can yield overall performance, only detailed physics-based modeling can probe down to such levels as detailed liquid saturations. As another example, effective management of water produced in the fuel cell can alleviate flooding of the catalysts and drying out of the membrane over the full operating temperature range. However, ineffective water management leads to liquid-phase water blockage and mass-transport-limited performance or decreased protonic conductivity in the membrane and catalyst layers due to dehumidification of the ionomer. This balance and its optimization is ideally suited to mathematical modeling.
In addition, simulation is invaluable in the development and use diagnostic tools, as well as the elucidation of controlling phenomena, conditions, and properties. Such analyses benefit DOE through cost-effectively focusing efforts in the experimental space.
Areas for further R&D include:
- Model validation
- Identification of rate-limiting steps and strategies to mitigate them.
- Increased understanding (not design-specific) of the water, gas, and electronic/protonic transport in fuel cell components.
- Development of understanding of cell component interactions and interfaces/structures and how they affect transport and performance and how these properties change during operation.
- Prediction of fuel cell package (plate-to-plate inclusive) performance using plate, gas diffusion layer (GDL), and membrane electrode assembly (MEA )chemical and structural data under a full range of operating conditions.
- New diagnostic techniques both in and ex situ to determine critical model parameters and properties.
- Better understanding of the effects of freeze/thaw cycles on fuel cell components, cells, and stacks to guide development of mitigation strategies which include identification of failure modes during freezing (e.g., morphological changes and localized stresses in fuel cell components associated with phase transition), and delineation of water movement under temperature gradients and multiphase transport in porous media under freezing conditions including phase-change kinetics.
The goal of the Transport Modeling Working Group, through close cooperation and coordination of the activities of the DOE Fuel Cell Technologies Office-funded transport focused projects, is to address the gaps in understanding as identified by DOE to enable fuel cell systems to meet DOE performance and durability targets. Transport project descriptions from the 2010 DOE Hydrogen Program and Vehicle Technologies Program Annual Merit Review and Peer Evaluation Meeting summarize the DOE Fuel Cell Technologies Office's transport related R&D activities and accomplishments.
Technical Targets for Fuel Cell Performance
The Department of Energy, with input from the Fuel Cell Technical Team of the US DRIVE, has developed a set of targets for fuel cell stack, system, and cell performance and durability. These targets relate directly to issues of transport phenomena within fuel cells. These targets are contained in the Multi-Year Research, Development, and Demonstration Plan, Fuel Cells Section, which is currently under review.
The Transport Modeling Working Group held its kickoff meeting at Lawrence Berkeley National Laboratory on February 18, 2011.
The following people can be contacted for more information about the Transport Modeling Working Group.
DOE Fuel Cell Technologies
Fuel Cells Team Lead
U.S. Department of Energy, EE-2H
1000 Independence Avenue
Washington, DC 20585-0121
Dr. Adam Weber
Lawrence Berkeley National Laboratory
1 Cyclotron Rd, MS 70-108B
Berkeley, CA 94720
Dr. Rangachary Mukundan
MPA-11, MS D429
P.O. Box 1663
Los Alamos, NM 87545