Lightweight High-Performance Fuel Cells for Unmanned Aerial Vehicle Propulsion

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A Proton Exchange Membrane Fuel Cell (PEMFC) converts the chemical energy of hydrogen directly into electrical energy with the generation of water and heat. The PEMFC powerplant is the most promising power source for automotive and distributed power applications. Currently PEMFCs are regarded as the alternative power source for Unmanned Aerial Vehicles (UAVs). However, compared with other power sources (e.g., internal combustion engine, battery, and turboprop) that have been used to power UAVs, the power density of the PEMFC powerplant is much lower. Thus, the low power density (low power output by a heavy fuel cell powerplant) is the most critical challenge for fuel cell-powered UAVs (FCUAVs). Conventional graphite bipolar plates contribute almost 80% of a fuel cell stack weight. Membrane hydration is one of the most critical challenges for low-temperature (~70 C) PEMFCs as it directly affects the fuel cell performance and efficiency. In order to properly hydrate the membrane, with the conventional technologies, a separate humidifier and related systems are usually required, which makes the conventional fuel cell powerplants heavy and bulky. The Principal Investigator's group has made significant contributions in the fields of PEMFCs and PEMFC-Battery Power Systems: (1) A comprehensive three-dimensional General Model of PEMFCs was developed, implemented, and applied to deal with two-phase flow and transport mechanisms. (2) A Fuel Cell Test Stand was successfully built, improved, and employed to investigate fuel cell performance and validate the General Model of PEMFCs. (3) An electrospinning setup has been designed and built to fabricate nanofibers and catalyst-coated gas diffusion layers with better durability and higher performance. (4) Power management strategies for fuel cell-battery hybrid systems with vehicles and portable applications have been developed and the experimentally validated. (5) FCUAV prototyping with a focus on the control strategies for the fuel cell powerplant. In order to build a FCUAV with high efficiency and long endurance, there is an urgent need to develop an effective systematic methodology for building a lightweight PEMFC stack with innovative designs and by effective and affordable fabrication methods. In this proposal, innovative designs and fabrications of membrane, electrode, and bipolar plates will be proposed, characterized, and investigated by numerical and experimental methods; and an effective systematic methodology for building a lightweight PEMFC stack with high performance will be established. The results of the proposed research will significantly improve the performance and reduce the cost of PEMFCs. Along with the highly qualified personnel trained and the expertise developed, it will have positive and substantial effects on FCUAVs for defence and civilian applications.