Energetic and exergetic assessment of operating biofuel, hydrogen and conventional JP-8 in a J69 type of aircraft turbojet engine

In the present paper, an extensive energetic and exergetic assessment of a turbojet engine powered by biofuel, hydrogen and JP-8 fuels is performed in view of the thermodynamic principles. According to the results; when the engine fed with the biofuel, the fuel mass stream incremented from 0.16 to 0.184 kg s −1 compared to the utilization of JP-8 fuel, however, the fuel mass stream decreased from 0.184 to 0.058 kg s −1 compared to the utilization of hydrogen fuel. While the exhaust gaseous mass stream rate increased from 9.21 to 9.234 kg s −1 compared to the utilization of JP-8 fuel, it reduced from 9.234 to 9.108 kg s −1 utilization hydrogen. The produced kinetic energy rate by the turbojet engine which is equal to kinetic exergy rate increased from 1130.62 to 1133.63 kW, it is obtained to be 1118.07 kW for the hydrogen fuel. On the other hand, the energy efficiency of the engine increased from 16.39 to 16.43%, compared to the JP-8 fuel utilization, the specific fuel consumption of the engine rose from 0.035 to 0.040 kg kN −1 s −1 , while the exergetic efficiency of the engine decreased from 15.34 to 15.25% compared to the JP-8 fuel usage and increased from 14.36 to 15.25% compared to the hydrogen utilization case. The engine’s environmental effect factor has risen from 5.52 to 5.56 compared to the JP-8 utilization, the exergetic sustainability index of the overall engine increased from 0.168 to 0.180 compared to the hydrogen utilization case.