Abstract: A new compressed air engine system based on two-stage single screw expander is proposed to increase the energy utilization rate of compressed air. The distribution of expansion ratios between stages is optimized by building mathematical optimal arithmetic model with variable metric method and is checked by programming calculation. The influence of total efficiency and heating temperature on the power performance parameters including total output work and air consumption rate is analyzed. Research results indicate the best match of expansion ratio is ten to seven (nine to seven and nine to eight are also good) for the same inlet temperature system with air tank of 30 MPa pressure and 300 L volume. Results also show that heating up inlet air or increasing the system efficiency can improve the total output work and reduce the air consumption rate. It is concluded that the compressed air engine system combined two-stage single screw expander with heating is better than single-stage system.

Key words: Air powered engine, Compressed air, Single screw