Evaluation of Heat Transfer Technologies for High Temperature Polymer Electrolyte Membrane Fuel Cells as Primary Power Source in a Regional Aircraft

Abstract

As the world transitions away from fossil fuels, alternative methods of energy storage and conversion are in the center of many research endeavours. Aviation poses a unique challenge for decarbonization due to the demand for high specific energy and power density of the aircraft propulsion system. Hydrogen-electric technologies employing fuel cells, are among the most promising approaches for achieving zero-emission flight. However, thermal management of fuel cell systems remains a significant challenge due to the limitations of conventional liquid cooling architectures. These systems require bulky heat exchangers and consume substantial parasitic power, and consist of multiple subsystems, adding complexity to the propulsion system. To address these challenges, this study proposes integrating novel hexagonal pulsating heat pipes into a High Temperature Polymer Electrolyte Membrane fuel cell stack to transfer heat from the center of the stack and reject it to an external airflow. The research aims to determine whether this approach can reliably control the fuel cell’s operating temperature, while potentially reducing system weight, complexity, and reliance on parasitic power. The thermal performance of the proposed system is evaluated based on equivalent thermal conductivity measurements from literature. To minimize computational demand, a singular pipe simplification is developed and its thermal behavior investigated numerically and analytically. The results demonstrate that, under some conditions, the heat pipe system is able to keep the fuel cell’s operating temperatures below 200 °C. A parameter study is conducted to evaluate the effects of heat pipe length, external air flow speed and equivalent thermal conductivity on the thermal performance. As an exemplary case from the parametric study, a configuration with a condenser length of 5 cm, coolant air speed of 3 m s−1, and an equivalent thermal conductivity of 3300 W m−1 K−1 yielded a maximum cell temperature of 140 °C and a temperature difference of 10.2 °C across the 10 cm-long cell, highlighting the theoretical feasibility of the concept.