Sensitivity of exergy efficiencies of aerospace engines to reference environment selection

Abstract

Exergy analysis is applied to a turbojet engine over flight altitudes ranging from sea level to 15 000 m (∼50 000 ft), to examine the effects of using different reference-environment models. The results of this analysis using a variable reference environment (equal to the operating environment at all times) are compared to the results obtained using two constant reference environments (sea level and 15 000 m). The actual rational efficiency of the turbojet decreases with increasing altitude, ranging from a value of 16.9% at sea level to 15.3% at 15 000 m. In the most extreme cases considered, the rational efficiency calculated using a constant reference environment varies by approximately 2% from the variable reference environment value.