Dynamic simulation and structural analysis of improved adiabatic compressed air energy storage system based on liquid piston

As the scale of renewable energy installation continues to expand, large-scale energy storage technology has become one of the key solutions to address issues such as energy fluctuations and improve energy efficiency. In this work, a novel liquid piston adiabatic compressed air energy storage (LPA-CAES) system is proposed to improve the output flexibility of turbines. For the LPA-CAES system, the discharging process is divided into liquid piston expander expansion and two-stage expander expansion. The non-design models of various components in the system were established, and validation was conducted using experimental data from open literature. According to results, optimization was performed on parameters such as the number of compressor stages and the allocation of compressor pressure ratios during the charging process, and an analysis of the charging process characteristics was conducted. Meanwhile, the proposed LPA-CAES system was compared with traditional A-CAES systems. The results show that at the lowest design pressure of 4 MPa, the round-trip efficiency (RTE) of the LPA-CAES system is 69.22 %, while that of the A-CAES system is only 67.6 %. The RTE increment between the two systems is 1.82 %. The LPA-CAES system can provide a smaller output power (0.2–0.3 MW), while ensuring efficiency and offering multiple power output capabilities. Overall, combining liquid piston technology with A-CAES systems can enhance system flexibility and provide more methods for the design of A-CAES systems.