Conventional and advanced exergy analysis of a two-stage air compressor for fuel cell

High efficiency air compressors can significantly reduce the parasitic power consumption of fuel cell systems, thereby improving the cruising range and economy of the vehicle. This study investigates the irreversible loss characteristics of a two-stage centrifugal air compressor by using conventional and advanced exergy analysis. An air compressor test bench was established to obtain aerodynamic performance data. A numerical model of the two-stage air compressor was validated against the experimental data. The conventional exergy results show that the total exergy destruction is 4942.68 W, of which the low-pressure and high-pressure impellers account for 59.20%. The advanced exergy analysis further indicates that endogenous exergy destruction and avoidable exergy destruction dominate the system loss, accounting for 76.02% and 88.15%, respectively. The high-pressure impeller has the largest avoidable endogenous exergy destruction, reaching 1491.96 W, and should therefore be regarded as the primary optimization target. The local irreversible mechanism analysis shows that turbulent dissipation is the dominant source of exergy destruction in the high-pressure impeller, especially near the blade leading edge, blade tip region and outer flow passage. The results provide guidance for the structural design and optimization of fuel cell air compressors.