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This paper presents a novel approach to the design of fuel cell thermal management systems, offering significant advantages for the evaluation of system architectures and design variables. The new performance calculation method considers the flow of cooling air as a separate cycle process. Analytical correlations are employed to describe the cycle process that the cooling air undergoes as it flows through the thermal management system, similar to the cycle process of an aircraft gas turbine. The power, efficiency, and other variables of the propulsion system are determined by merging the cycle processes of the propeller and the thermal management, as well as the energy conversion in the electric powertrain. We illustrate the capabilities of this approach through a sensitivity study of a small aircraft propulsion system with a required thrust of 1000N at a cruise speed of 85m/s. This study examines the impact of three exemplary design variables – cooling fan pressure ratio, heat exchanger frontal area and fuel cell current density – on the overall performance of the reference propulsion system. Optimal values for these design variables have been determined to achieve maximum efficiency and minimum propulsion system mass. For example, a thermal management design without a cooling fan has a lower overall efficiency (−18.2%) and higher mass (+17.3%) compared to a design with a cooling fan pressure ratio of 1.04. In summary, this paper presents a method for designing the thermal management of a fuel cell propulsion system and discusses the impact of design variables on engine performance. The insights provided can help engineers to optimize fuel cell propulsion system design in terms of efficiency, mass, and hydrogen consumption.
Niehuis et al. (Fri,) studied this question.