Minimising the effect of degradation of fuel cell stacks on an integrated propulsion architecture for an electrified aircraft

Zhou

Enalou

et al. 2023

Self Cite

All-electric aircraft can eliminate greenhouse gas emissions during aircraft mission, but the low predicted energy storage density of batteries (=0.5 kWh/kg), and their life cycle, limits aircraft payload and range for regional aircraft. Proton Exchange Membrane Fuel Cells (PEMFCs) using hydrogen are explored as an alternative power source. As the effort on designing high power density and highly efficient fuel cell systems continues, a trade off study on the effect of fuel cell configurations and the electrical conversion strategy on system efficiency, total weight, failure cases, and reduction of power due to failures, will inform future designs. Introducing viable fuel cell stacks and electrical configurations motivates such a trade off study, as well as concentrated design effort into these components. Currently available fuel cell stacks are designed at lower power (in the range of 150kW) to what is required for regional aircraft propulsion (in the range of 4MW). Hence to achieve the total required power, the fuel cell stacks are connected in parallel and series to create multi-stack configurations and provide higher power. In this study, multi-stack fuel cell configurations and the selected DC/DC converters are assessed. Each configuration is evaluated based on power converter design and redundancy, design for high voltage, degradation of fuel cell stacks, total system efficiency, and controllability of fuel cell stacks.

Section: Configurations Descriptionmentioning

confidence: 97%

“…FCvelocity®-HD6 Proton-Exchange Membrane Fuel Cell (PEMFC) stack operating points are chosen for this study. Table 2 presents FC parameters, and a detailed description of the model of the FC stack is presented in [21,22].…”

Section: Propulsion Systemmentioning

confidence: 99%

The Impact of Multi-Stack Fuel Cell Configurations on Electrical Architecture for a Zero Emission Regional Aircraft

Zhou

Enalou

et al. 2023

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“…CHARM is the Cranfield Hybrid electric Aircraft Research Model which is an integrated approach to explore various electrified propulsion technologies and their synergies. It comprises methods and tools for modeling and evaluating conventional and novel aircraft configurations [16][17] [18], designing and analyzing the performance of electric components, electrified architectures (E-HEART) [19] [20] and thermal management systems, and integrating them with the aircraft performance and mission analysis. The flight mission analysis is performed using Hermes, the in-house aircraft performance platform at Cranfield University [16] for a fully electrified aircraft with a propulsion architecture shown in Fig.…”

Section: Selected Electric Aircraft Propulsionmentioning

confidence: 99%

“…E-HEART is part of a digital-twin model being developed. The low fidelity FC model in E-HEART has been explained in [21] and [22].…”

Section: Selected Electric Aircraft Propulsionmentioning

confidence: 99%

The Impact of Electric Machine and Propeller Coupling Design on Electrified Aircraft Noise and Performance

Kiran

Sinnige

et al. 2023

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Novel propulsion systems have been studied in literature to reduce aircraft emissions with hydrogen or other electrical energy sources. Hybrid Electric Propulsion (HEP) system consists of electric machines as an alternative way to provide power for propulsion resulting in the reduction of aircraft fuel consumption. While reduction of emission is the main driver of new HEP designs, aircraft noise reduction and performance improvement will also need to be investigated. Much quieter electrified aircraft than conventional aircraft is explored with considering the benefits of coupled design between the propeller and electric machines. In this study, several electric machine designs have been explored and coupled with the propeller design to study the trade-off between the aerodynamic and acoustic performance of the propeller. Aerodynamic optimization is used as a baseline to minimize the energy consumption to find the aerodynamics optimum subject to constraints on the thrust levels during the mission. The propeller aerodynamic optimizer considers the electric machine efficiency map, which is a function of propeller torque and rotational speed, to find the optimum combination of propeller and electric machine designs. The objective function of the acoustic optimizations is to reduce the cumulative noise level over the entire mission. It is shown that a wider envelope of peak motor efficiency in the efficiency map provides acoustics and aerodynamic performance benefits. The trade-offs between reducing noise or increasing aerodynamic efficiency to reduce energy consumption are demonstrated.

“…5. The fuel cell stacks are connected in a configuration (4 parallel and 4 in series) that reduces the failure rate due to degradation of one of the stacks or the incompatibility between the stacks, which was studied in [33]. More details on the FC modeling and equations are provided in [33].…”

Section: Fig 4 Conceptual Schematic Of the 8-propeller Fc Aircraftmentioning

confidence: 99%

Integrated Mission Performance Analysis of Novel Propulsion Systems: Analysis of a Fuel Cell Regional Aircraft Retrofit

Pontika

Zhou

et al. 2023

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This paper presents the development and application of an integrated, higher-fidelity framework developed within CHARM (the Cranfield Hybrid electric Aircraft Model) for the design, performance analysis and overall evaluation of novel electrified propulsion systems. The developed framework is used to model and analyze the performance characteristics of a Fuel Cell (FC) regional aircraft system in comparison with a conventional regional aircraft and a hydrogen gas turbine regional aircraft retrofit. The FC propulsion system and the hydrogen gas turbine are retrofitted to the same conventional aircraft platform. Physics-based aircraft performance calculations, propeller maps, gas turbine component maps, off-design cycle analysis, electric component maps, calculations for the electric power management and distribution, and a Proton-Exchange Membrane FC (PEMFC) configuration sized to cover the power requirements of a regional aircraft, are integrated within this framework to capture the performance and interaction of components, sub-systems and aircraft during any flight mission and conditions. The aircraft performance, the propulsion system performance characteristics and the emissions of the three technologies are calculated and discussed to understand the challenges and opportunities of using hydrogen-electric propulsion (FC). The effect of capturing the variable mission parameters and flight phases on the performance of the electric power system and FC is presented and compared against a lower fidelity modeling approach for the electric powertrain. The sensitivity of the FC propulsion system and its attributes to varying mission requirements (island-hopping, range, cruise altitude, ambient conditions), as well as the change in the consumed fuel, are demonstrated. This framework can be used to inform the decision-making for the design of electric components and thermal management systems (TMS), and the importance of capturing the trade-off between mass, efficiency and operational constraints in the design process is highlighted. Also, the off-design performance of the electric power system designs and FC is modeled to decide if the design is within acceptable limits under various conditions, and capture the effect of mission requirements and flight conditions on the energy consumption of the overall aircraft system. Finally, a parametric analysis addresses the effect of power density improvement with future technology on the energy per passenger and feasibility of the FC regional aircraft.