Design and Analysis of a Baseline Fuel Cell Thermal Management System in a Conceptual Aircraft Design Framework

Hydrogen-fueled fuel cell aircraft require powerful thermal management systems to operate. The sizing and integration of these systems remain a key challenge for this type of propulsion system. This study investigates the impact of a fuel cell cooling system on a parallel-hybrid regional aircraft by means of integrating a cooling system model within a conceptual aircraft design workflow. The workflow includes key design parameters of the fuel cell and the thermal management system for co-optimization towards minimum aircraft CO2 emissions. The multi-objective optimization of the thermal management system includes a ranking of drag, mass and power consumption impacts. The thermal management system drag is found to have the largest impact at aircraft level. It is most affected by the heat exchanger fin geometry and frontal area. A wide-ranging drag-specific heat rejection of 1.8 to 14 kW/N is observed for the clean-sheet aircraft design during cruise flight. Larger frontal areas and the implied substantial reduction in thermal management drag outperform the drag increase in larger fairings that contain the heat exchanger. It is also shown how the optimization of the fuel cell load and operating temperatures can minimize the system penalty. This highlights the need for an integrated design approach to reduce the system impact.