Modeling, design and energy management of fuel cell systems for aircraft
Bradley, Thomas Heenan
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Fuel cell powered aircraft have been of long term interest to the aviation community because of their potential for improved performance and environmental compatibility. Only recently have improvements in the technological readiness of fuel cell powerplants enabled the first aviation applications of fuel cell technology. Based on the results of conceptual design studies and a few technology demonstration projects, there has emerged a widespread understanding of the importance of fuel cell powerplants for near-term and future aviation applications. Despite this, many aspects of the performance, design and construction of robust and optimized fuel cell powered aircraft have not been fully explored. This goal of this research then is to develop an improved understanding of the performance, design characteristics, design tradeoffs and viability of fuel cell powerplants for aviation applications. To accomplish these goals, new modeling, design, and experimental tools are developed, validated and applied to the design of fuel cell powered unmanned aerial vehicles. First, a general sub-system model of fuel cell powerplant performance, mass and geometry is derived from experimental and theoretical investigations of a fuel cell powerplant that is developed in hardware. These validated fuel cell subsystem models are then incorporated into a computer-based, application-integrated, parametric, and optimizeable design environment that allows for the concurrent design of the aircraft and fuel cell powerplant. These tools and methods are then applied to the analysis and design of fuel cell powered aircraft in a series of case studies and design experiments. Based on the results of the integrated fuel cell system and aircraft analyses, we gain a new understanding of the interaction between powerplant and application for fuel cell aircraft. Specifically, the system-level design criteria of fuel cell powerplants for aircraft can be derived. Optimal sub-system configurations of the fuel cell powerplant specific to the aircraft application are determined. Finally, optimal energy management strategies and flight paths for fuel cell and battery hybridized fuel cell aircraft are derived. The results of a series of design studies are validated using hardware in the loop testing of fuel cell propulsion systems and field testing of a series of fuel cell powered demonstrator aircraft.