Cross-scale dynamic simulation and operational strategy optimization of the compression process in aquifer-based compressed air energy storage systems

In this study, a cross-scale dynamic simulation method is proposed for the compression process of an aquifer-based compressed air energy storage (CAES) system, through which the coupling between dynamic operational conditions of the surface thermal system and real-time evolution of multi-physical fields during underground gas injection is achieved. A dynamic mathematical model has been established for centrifugal compressors, based on mass, momentum, and energy conservation principles. Data interaction and synchronous computation between Simulink and COMSOL are achieved through the Matlab/COMSOL API. Thus, cross-scale dynamic simulation research on the compression process of a saline aquifer CAES system is conducted. Under baseline conditions, the temporal variations in gas saturation, pressure, and temperature fields during compression in saline aquifers are simulated. The dynamic response of key state parameters, adiabatic efficiency, and input power in multistage compressors is analyzed via simulation during compression The effects of aquifer permeability, porosity, compressor pressure ratio, and wellbore diameter on backpressure, adiabatic efficiency, and input power dynamics in multistage compressors are simulated and discussed. A variable-speed control-based constant flow operation mode (N-mode) and a variable guide vane angle control-based constant flow operation mode (V-mode) are proposed. The thermodynamic performance of a three-stage centrifugal compression system is compared under conventional(D-mode), N-mode, and V-mode operations. The results indicate that the isentropic efficiency of compressors at each stage is the highest under the N-mode. The exergy efficiency of the entire compression process under the N mode is 1.99 % and 3.81 % higher than that under the D-mode and V-mode, respectively.