Influence of pressure losses on compressor performance in a pressurized fuel cell air supply system for airplane applications

Low ambient pressures at elevated flight altitudes lead to power losses in fuel cell powered aircrafts. As countermeasure ambient air can be pressurized with a suitable fuel cell air supply system. In this study the influence of low ambient pressures and pressure losses within the system on the performance of two turbo compressors and the resulting stack power are examined theoretically and the findings validated experimentally. Results show that decreasing ambient pressures and pressure losses in front and after the compressor reduce the maximum pressure from 2.4 to 1.6 bar(a) in the examined system. Air compression may require a significant share of the fuel cell stack power and the maximum system power is reduced from 54 to 41 kW. For air pressures higher than 1.8 bar(a) the fuel cell stack power gain due to pressurization is found to be cancelled out by the increasing power required for air compression.