Energy-saving performance of isobaric compressed air storage receivers in pneumatic systems

Pneumatic system powered by compressed air is one of the most common facilities in most industrial sectors, accounting for about 7% ~ 20% of total industrial electricity consumption in different countries. However, literature research reveals that the average energy efficiency of pneumatic systems is very low, which is much lower than the electric and hydraulic counterparts. Thus, compressed air is regarded as one of the most inefficient and expensive energy carriers. It also means that there is great potential for energy-saving in pneumatic systems. In this study, a novel isobaric compressed air storage receiver concept and the true flow control mode are proposed. Taking a typical pneumatic system as an example, the energy-saving performance is investigated by comparing isobaric receiver and traditional isochoric receiver. The thermodynamic second-law-based exergy is used for estimating the energy efficiency and available power in compressed air. The results show that many advantages over traditional air receivers could be achieved by introducing the isobaric air receivers in pneumatic systems. Thanks to the characteristic of isobaric storage. The pressure level of the system can be reduced and stabilized significantly, and energy consumption of compressors and exergy loss in throttling valves can be cut down; therefore, the overall efficiency of pneumatic systems can be improved dramatically. Besides, the energy storage density in air receivers can be improved significantly.