Experimental Investigation on the Performance of Compressors for Small-Scale Compressed Air Energy Storage in Parallel Mode

Abstract

The Compressed Air Energy Storage (CAES) system is a promising energy storage technology that has the advantages of low investment cost, high safety, long life, and is clean and non-polluting. The compressor/expander is the core equipment of the CAES system, and its performance has a decisive impact on the overall system efficiency and economic performance. Based on the pneumatic motor, this study proposes and designs a test bench of the CAES system that integrates compression and expansion functions. The off-design operation condition represented by the pressure change in the air tank has an important influence on the efficiency and economy of the CAES system. The effect of key parameters such as air tank pressure, torque, and mass flow rate on the output and efficiency of the compressor is investigated. When the CAES system is operating in energy storage mode, the compressor must continuously deliver gas to the gas storage. The working pressure of the compressor increases with the pressure in the air tank, so the compressor used for energy storage must operate continuously over a wide range of working conditions. The parallel operation mode of the compressor is proposed to improve the working condition range of the compressor torque and current, and improve the isotropic efficiency. When the air receiver pressure is 2.6 bar and the rotational speed is 2850 r/min, the power consumption of the compressor reaches the maximum value of approximately 1233.1 W. This new parallel mode could provide a CAES unit a systematic solution.