Recognizing the advantages of proton-exchange-membrane (PEM) fuel cell technology over existing alkaline fuel cell technology for space applications, NASA embarked on a 5-year PEM fuel cell powerplant development program in 2001. This program recently culminated with the delivery of a 7- to 10-kW engineering model (EM) to NASA for evaluation testing (see the photograph). NASA’s 5-year program was conducted by the three-center NASA team of Glenn Research Center (lead), Johnson Space Center, and Kennedy Space Center. It was initially aimed at developing PEM fuel cell hardware for a reusable launch vehicle application, but more recently it shifted to applications supporting the NASA Exploration Program.
PEM 7- to 10-kW EM fuel cell powerplant.
The first step in demonstrating the suitability of PEM fuel cell technology for space applications was evaluation testing of the 7- to 10-kW EM. The key requirements and goals for this powerplant are summarized in the table. As delivered to NASA, the EM powerplant met all of the program requirements and goals for power, voltage regulation, response time, operating temperature, operating pressure, and powerplant volume. The powerplant weight was 25 percent in excess of the goal. Schedule and cost constraints prevented further reductions in balance-of-plant weight surrounding the fuel cell stack, which was the major contributor to the excess.
| Requirement | Goal |
|---|---|
| Nominal power, kW | 7 to 0 |
| Voltage regulation, percent | 30±10 |
| Voltage response time, sec | <0.2 |
| Operating life, hr | 10,000 |
| Operating temperature, °C | 60 to 80 |
| Operating pressure, kPa | <690 |
| Powerplant weight, kg | <140 |
| Powerplant volume, m3 | <0.2 |
Initial evaluation tests, which were performed in Glenn’s Fuel Cell Test Laboratory, consisted of a calibration series test, a rapid startup test, and a performance load profile. Mission profile, loss of coolant tests, and environmental performance tests are currently underway. The EM powerplant was tested in three different spatial orientations to evaluate gravitational effects on the overall performance of the fuel cell stack and supporting ancillaries.
Teledyne EM performance load profile test results.
Initial analysis of the test results to date has shown the EM powerplant performance to be largely independent of spatial orientation (see the preceding graph). The benchmark performance test also showed that the EM can achieve stable operation after experiencing large changes in the power load in less than a millisecond (see the following graphs). In addition, the EM powerplant’s response times were evaluated under the rapid startup test; results indicate that the powerplant can deliver 50 percent of its rated capacity 5 sec after coming online with no preheating (see the final graph).
Teledyne EM transient response to change in load. Left: Load increased from 51 to 357 A. Right: Load decreased from 357 to 51 A.
Teledyne EM rapid startup test results; 50-percent capability 5 sec after start.
Vibration and thermal vacuum testing are underway at Johnson. The final tests to be performed at Glenn are the mission profile and the loss-of-coolant test. The mission profile measures the EM power-plant performance over a continuous 240-hr power profile that is representative of future missions, and the loss-of-coolant test is used to evaluate the powerplant performance when a secondary cooling system external to the power- plant is interrupted. Testing is scheduled for completion in early 2007.
Find out more about this research:
Glenn’s Electrochemistry Branch:
http://www.grc.nasa.gov/WWW/Electrochemistry/
Exploration Systems research at Glenn: http://exploration.grc.nasa.gov
Glenn contacts:
Dr. Patricia L. Loyselle, 216-433-2180, Patricia.L.Loyselle@nasa.gov
Mark A. Hoberecht, 216-433-5362, Mark.A.Hoberecht@nasa.gov
Analex Corporation contact:
Kevin P. Prokopius, 216-433-6137, Kevin.P.Prokopius@nasa.gov
Authors:
Kevin P. Prokopius, Mark A. Hoberecht, and Dr. Patricia L. Loyselle
Headquarters program office:
Exploration Systems Mission Directorate
Programs/projects:
Exploration Technology Development Program
Last updated: December 14, 2007
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