Evaluation of heat transfer technologies for high temperature polymer electrolyte membrane fuel cells as primary power source in a regional aircraft

Abstract High-temperature proton exchange membrane fuel cells (HT-PEM FCs) represent a promising avenue for generating carbon dioxide-free electricity through the utilization of hydrogen fuel. These systems present numerous advantages and challenges for mobile applications, positioning them as pivotal technologies for the realization of emission-free regional aircraft. Efficient thermal management of such fuel cell-powered systems is crucial for ensuring the safe and durable operation of the aircraft, while concurrently optimizing system volume, mass and minimizing parasitic energy consumption. This paper presents four distinct heat transfer principles tailored for the FC-system of a conceptual hydrogen-electric regional aircraft, exemplified by DLR’s H2ELECTRA. The outlined approaches encompass conductive cooling, air cooling, liquid cooling, phase change cooling and also included is the utilization of liquid hydrogen as a heat sink. Approaches are introduced with schematic cooling architectures, followed by a comprehensive evaluation of their feasibility within the proposed drivetrain. Essential criteria pertinent to airborne applications are evaluated to ascertain the efficacy of each thermal management strategy. The following criteria are selected for evaluation: safety, ease of integration, reliability and life-cycle costs, technology readiness and development as well as performance, which is comprised of heat transfer, weight, volume and parasitic power consumption. Of the presented cooling methods, two emerged to be functionally suitable for the application in MW-scale aircraft applications at their current state of the art: liquid cooling utilizing water under high pressure or other thermal carrier liquids and phase-change cooling. Air cooling and conductive cooling have a high potential due to their reduced system complexity and mass, but additional studies investigating effects at architecture level in large-scale fuel cell stacks are needed to increase performance levels. These potentially suitable heat transfer technologies warrant further investigation to assess their potential for complexity and weight reduction in the aircraft drivetrain.