System Modeling of FLyCLEEN Gas Turbine-Solid Oxide Fuel Cell Aircraft Engine Concept

A thermal-fluid system model is constructed in Aspen Plus to assess the performance of a hybrid gas turbine-solid oxide fuel cell system for aircraft propulsion using kerosene-based jet fuel and hydrogen fuel. In the FLyCLEEN (FueL CelL Embedded ENgine) system, a solid oxide fuel cell (SOFC) stack is integrated into the combustion chamber wall. A portion of the kerosene-based fuel and compressor airflow is reacted in a catalytic partial oxidation (CPOX) reformer to form a stream of syngas fuel, which is then reacted in the SOFC. Unburned fuel from the SOFC and waste heat from the CPOX reformer and SOFC are injected into the combustor downstream of the primary combustion zone to increase system efficiency. The thermal-fluid model includes the CPOX reformer, the SOFC, the thermal management system, the combustor, and the power conversion of the electricity generated by the SOFC. The thermal-fluid model is used to study the impact of the FLyCLEEN system on a turbofan engine for narrow-body aircraft at cruise. Multiple use cases for the electricity generated by the SOFC are examined, including propulsive power, accessory power, and the combination of both propulsive and accessory power. It is found that for all the electricity use cases studied, the addition of the FLyCLEEN system results in improved engine performance. Increasing the fraction of propulsive power generated by the SOFC further improves engine performance, resulting in a 11.1% decrease in specific fuel consumption and a 4.9% overall engine efficiency improvement when 25% of the engine propulsive power is generated by the SOFC. A variant of the model is also constructed for a hydrogen-fueled engine. The use of hydrogen fuel allows for the removal of the CPOX reformer, resulting in a slight improvement in FLyCLEEN system performance compared to the kerosene-fueled engine.