Advanced exergy and graphical exergy analyses for solid oxide fuel cell turbine-less jet engines

Fuel cell technologies are applied to the propulsion systems on aircraft to save fuel and reduce emissions. A novel hybrid engine with low specific fuel consumption by integrating solid oxide fuel cells and turbine engines is proposed in our previous papers. However, the real performance potential of the engine and the interrelation among the components have not illustrated. To demonstrate the irreversibility and show the energy flow paths of the engine, the advanced exergy and thermodynamic performance models are built and the main parts are validated. The conclusions are as follows: (1) The exergy efficiency of the engine is 49.8%. (2) The avoidable endogenous exergy destruction ratio is just 12.9%, which indicates that lots of exergy destruction rates can not be avoided by improving the components. The endogenous exergy destruction ratio is 88.5%, which means that the relationship between the components is not close. (3) Traditional exergy analysis suggests that the first improvement priority should be given to combustors, and then to SOFCs and heat exchangers. However, the order of priorities for improvements as suggested by advanced exergy analysis is different. This revised order should be first the nozzle, then the compressor, the heat exchanger, and the motor.