Performance and Evaluation of Bipolar Fuel Cell Stacks
Progress rept. Oct 1998-Sep 1999
ARMY RESEARCH LAB ADELPHI MD
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Under a joint technology planning annex TPA agreement, fuel cell groups at the U.S. Army Research Laboratory ARL and the U.S. Army Communications-Electronics Command CECOM worked together to develop Army power sources for soldier applications. Two 50-W bipolar fuel cell stacks designed by CECOM were extensively evaluated. The performance of the stacks depended significantly on the environmental temperature. Decreasing environmental temperature granted better heat dissipation in the stacks, resulting in improved stack performance. Long-term performance of 62 W was obtained at low temperature -5 deg C. Higher environmental temperatures caused an increase in stack surface temperature. When the stack surface temperature reached 43 deg C, the stack voltage dropped to zero within a short time. The maximum power density for long-term operation was 97.3 Wkg, or 167 WL. The average hydrogen utilization efficiency was 95 percent. The water production efficiency was dependent on the discharge currents, varying from 40 percent at 1.0 A to 90 percent at 2.5 A.
- Electrochemical Energy Storage