Thermal Management in High Temperature Proton Exchange Membrane Fuel Cells for Aircraft Propulsion Systems

Proton Exchange Membrane Fuel Cells (PEMFCs) are a leading propulsion technology candidate for net zero carbon dioxide emission aircraft. PEMFCs generate electrical power and byproduct heat via an electrochemical reaction between hydrogen and oxygen reactants. The electrical power generates thrust from motor driven propellers and the byproduct heat is rejected to atmosphere through a Thermal Management System (TMS). Thermal management of PEMFCs is more complex than jet engines because the heat cannot be as readily dissipated to the atmosphere. Increasing the operating temperature of PEMFCs is desirable as it increases the driving temperature between the TMS coolant and the atmosphere. This is advantageous from an aerospace perspective because for a given heat load it enables downsizing (and thus lightweighting) of the TMS with an associated reduction in drag. This review considers High Temperature (HT) PEMFCs that operate at temperatures between 100 and 250 °C owing to these advantages. In wider literature there are several TMS architectures that are being actively considered for HT-PEMFCs. A detailed review of literature pertinent to these HT-PEMFC TMS architectures, and their design and operation, is presented in this paper. This review is subsequently used to identify gaps in knowledge in the following thematic areas: powerplant, direct cooling, indirect cooling, heat absorption, primary heat exchanger, and operation (shutdown, cold start, and thermal transients). These gaps provide future research challenges that need to be expediently addressed to facilitate convergence to suitable solutions for HT-PEMFC TMS in aviation.