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 elec-tricity 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 ther-modynamic 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.