April 5th, 2012
Econintersect: A research team at Michigan Technological University is close to developing a mathematical model that deals with a persistent poison for hydrogen fuel cells. Water, which is a product of the fuel cell reaction of hydrogen and oxygen, also prevents further reaction of the gases if it is not removed quickly and completely from the reaction site. The Michigan Tech team, led by Jeffrey Allen, has developed a model that predicts the behavior of water with a high degree of accuracy for four different types of transport layers used in fuel cell construction. Refinement of the model to include temperature and evaporation remains for the project, as well as extension to tests of new types of materials. Click on image for larger picture of simple fuel cell design concept.
Follow up:If successfully concluded, this research will drastically reduce time spent in trial and error experimentation with new materials by screening classes of candidates to select the most promising.
From the Michigan Tech News:
Most of that watery action happens in the fuel cell’s porous transport layer, or PTL, which is not much thicker than a coffee filter. That’s where all the byproducts of the fuel cell’s power-generating reaction meet up with a catalyst and react to form water vapor.
It’s not easy to find out exactly what’s happening in the PTL. “Everything is compressed like crazy,” says Allen, the John F. and Joan M. Calder Associate Professor in Mechanical Engineering. “You have to get the gases—hydrogen and air—to the catalyst, and you have to get the water away. Figuring out how to do this has largely been a matter of trial and error.”
The latest generation of hydrogen fuel-cell engines does an excellent job of managing water, but as new materials and designs enter the arena, the industry is again faced with a long, costly experimental process to determine the best configuration.
“There’s a whole new class of catalysts coming out, and we want to make sure it doesn’t take another 20 years to optimize the materials set,” says Allen.
Optimizing those up-and-coming materials to get rid of water is especially difficult, because the movement of water in the PTL appears to be random. “But that’s what we’re trying to predict,” he says.
At high flow rates, water spreads out evenly. But when the flow rate is low, as it is in an operating fuel cell, it spreads out in irregular shapes like an amoeba, a process called “fingering.” Other factors come into play as well, including how saturated the PTL is.
Allen’s team incorporated those variables into a mathematical model with the aim of forecasting the movement of water. Then they tested it using four different types of PTL and found that they could predict how water would behave with a high degree of accuracy.
“We were really excited,” Allen says. “This is the first time anyone has validated a model in a real sample. We’re at the point where, by adjusting just one parameter, we are able to duplicate experimental results exactly.”
- Michigan Tech breakthrough could slash R&D time for hydrogen fuel cells (R&D Magazine, 4 April 2012)
- Michigan Tech Breakthrough Could Slash R&D Time for Next Generation Hydrogen Fuel Cells (Marcia Goodrich, Michigan Tech News, 3 April 2012)