Abstract: To know energy efficiency utilization and obtain a high capacity usage ratio for the air power system based on single-screw engine, the energy loss for each process and the total output work are analyzed, also the influence of exhaust pressure on energy distribution is studied emphatically by taking energy analysis method and thermodynamic theory concerning non-steady flow with variable mass system. The results indicate that adopting low exhaust pressure is good for increasing the mass and energy utilization efficiency of the power system. The mass utilization ratio is more than 90 percent while energy efficiency is low, which is due to great energy losses during decompression and exhaust process. Where, the energy loss produced during decompression process takes more than half of the total energy. Therefore, how to reduce the energy loss during the said two main processes is the key point to increase energy utilization of the power system, especially for the decompression process.

Key words: Air-powered vehicle, Energy efficiency analysis, Engine, Single-screw