Performance Analysis of CO₂ Energy Storage System with Absorption Refrigeration Cycle

A CO₂ energy storage system with absorption refrigeration cycle was proposed, which adopted a split flow method to divert a portion of CO₂ to the secondary compressor, the heat generated by the secondary compression was provided to the absorption refrigeration cycle, which provided cooling capacity for the main CO₂ in system, and used the high-pressure storage tank to store CO₂ in the liquid state, to improve the system energy storage efficiency. Thermodynamic analysis and multi-objective optimization of the system were carried out. Results show that the absorber, first stage compressor, turbine and post stage heat exchanger have relatively high exergy destruction under design condition. The system energy storage efficiency increases with the increase of condensation pressure, the adiabatic efficiency of compressor and turbine. However, the system energy storage efficiency decreases with the increase of the storage pressure. The optimal energy storage efficiency and energy density of the system are 68.70% and 0.153 kW·h/m³, respectively.