In order to improve the charge and discharge efficiency of advanced adiabatic compressed air energy storage(AA-CAES) system

a novel AA-CAES system with variable pressure ratio is proposed. The time for energy release

the total output work of expansion unit stages

and the charge and discharge efficiency of the whole system under various configurations and operation modes are obtained by establishing the thermodynamic model of the system and calculating the thermodynamic characteristics of the system under different expansion unit stages and different variable expansion ratio operation modes. The results show that

for the AA-CAES system with 4-level expansion

the variable expansion ratio make the time for energy release of the expansion unit stages increase from3 095 s to 5 014 s

the total output work increase from 1.953 GJ to 2.728 GJ

the charge and discharge efficiency of the whole system increase from 45.11% to 63.00%. It can be seen that the AA-CAES with variable pressure ratio can significantly improve the thermodynamic performance of the AA-CAES system.