Impact of Fuel-Cell Stack Size and Atmospheric Conditions on Contrail Formation

Kurzfassung

The growing interest in hydrogen-powered aircraft calls for an assessment of their non- CO2 climate effects. This study applies an existing fuel-cell simulation model to investigate the potential for contrail formation from water vapor and heat emissions of fuel-cell propulsion systems. The simulation output is coupled with a theoretical contrail-formation framework and transferred to a standard winter mid-latitude atmosphere to evaluate the thermodynamic thresholds for condensation. Five different fuel-cell stacks with varying numbers of cells are analyzed to assess the influence of stack size on system efficiency, waste-heat release, and water vapor emissions. A cryogenic hydrogen-electric propulsion concept based on a modified ATR 72 platform, powered by a modular PEMFC system, is used as a case study. The minimum contrail formation temperature TLM is primarily influenced by ambient pressure and temperature, while fuel cell operating voltage and exhaust plume characteristics play a secondary role. Averaged results show a moderate positive correlation between TLM and overall system efficiency η, although atmospheric variability dominates contrail formation probability, with the highest occurrence in subarctic winter and lowest in subarctic summer. The findings indicate that optimizing hydrogen-fuel-cell propulsion for efficiency does not inherently increase contrail formation risk. The study demonstrates the applicability of integrating scalable fuel cell modeling with atmospheric contrail assessment for early-stage aircraft design, providing a framework to evaluate propulsion system configurations in relation to environmental impact.