Performance of compressed air energy storage system under parallel operation mode of pneumatic motor

Compressed air energy storage is a promising technology with the advantages of zero pollution, long lifetime, low maintenance, and minimal environmental impact. However, compressed air energy storage has some disadvantages, such as low efficiency and low energy density. A parallel operation mode of pneumatic motor is proposed in this study to improve the power performance, energy conversion efficiency, and economy of compressed air energy storage system. First, the test bench of compressed air energy storage system is established. Then, the influence of key parameters, such as current, rotating speed, and regulated pressure, on the output performance of compressed air energy storage system is investigated in this study. Afterward, the interaction among volume flow rate, rotating speed, torque, output power of pneumatic motor, and the current, voltage, and output power of the generator, as well their influence on one another, are discussed. Finally, the output performances of compressed air energy storage system when the pneumatic motor works alone and in parallel are compared and analyzed. The experimental results show that the power performance, energy conversion efficiency, and economy of compressed air energy storage system can be improved when the pneumatic motor works in parallel operation mode. The minimum compressed air consumption rate is 0.1369 g/J, the maximum power output is 818 W, the maximum efficiency of the generator is 88.7%, and the maximum efficiency of pneumatic motor is 6.5% when the pneumatic motor works in parallel operation mode.