Thermodynamic analysis of photothermal-assisted liquid compressed CO2 energy storage system hybrid with closed-cycle drying

Liquid compressed carbon dioxide (CO2) energy storage (LCES) is promising by mechanically storing the electricity into the high-pressure liquid CO2. However, the thermal efficiency of the expander, i.e., energy release process, is strictly limited by the outlet temperature of the compression heat storage. To this end, a photothermal-assisted LCES system is proposed to increase the inlet temperature of expander. A heat integration scheme of the new system is proposed by deploying the closed-cycle drying chamber for the waste heat recovery, whose performance is compared with the conventional organic Rankine cycle (ORC) method. By developing the thermodynamic models of the systems, numerical results indicate that the photothermal assistance significantly enhances the thermal performance of LCES system, with the exergy efficiency increased by 16.00 % to 62.23 % and the energy storage density increasing from 8.06 kWh/m3 to 18.59 kWh/m3, respectively. The comparative results of different waste heat recovery schemes show that the closed-cycle drying is of 2.77 times waste heat recovery benefit of the ORC method, with a dehumidification capacity being 63.45 kg/h. Moreover, the closed-cycle drying subsystem with a recuperator is designed to recover the sensible heat of the moist air at the outlet of the drying chamber, which further improves the dehumidification capacity by 52.04 % at a drying chamber outlet temperature of 319.15 K.