Performance characteristics of a solid oxide fuel cell hybrid jet engine under different operating modes

Solid oxide fuel cell (SOFC) technology is promising. Jet engines can be integrated with SOFCs (SOFC hybrid jet engine) for aircraft. The specific thrust of the engine is greatly improved by replacing turbines with SOFC systems. Four operating modes are designed for the engine to achieve about 50% ∼ 100% thrust variation. Mode 1: Regulating the fuel flow in the reformer under the constant air flow for the SOFC system. Mode 2: Regulating the fuel flow in the afterburner with zero fresh air for afterburners. Mode 3: Regulating the fuel and air flow for the SOFC. Mode 4: Regulating the fuel flow in the afterburner with constant air flow for afterburners. The performance and thermodynamic parameters of the engine under different operating modes are examined and compared according to the built mathematical models. The simulation results show that the effects of operating modes on the engine are remarkably different from that on the traditional SOFC gas turbine hybrid systems for electricity generation. All of the parameters of components change sharply in modes 1 and 3, and the thermal efficiency of the engine increases respectively from 0.577 to 0.687 and 0.491 to 0.687 with the increase of load. The component parameters of the engine are slightly changed in modes 2 and 4 except the parameters related to the afterburner. In mode 2, the thermal efficiency decreases from 0.577 to 0.454. It decreases from 0.491 to 0.434 in mode 4. In a nutshell, the performance of the engine can be varied in a wide range under the operating model 4 with increasing the afterburner temperature from 832 K to 2261 K. The operating mode 4 is the best.