Thermodynamic analysis of a novel radial-flow cryogenic packed bed for liquid air energy storage

With the rapid penetration of renewable energy in power grid, the necessity for large-scale, long-duration energy storage technologies has become increasingly evident to enhance grid flexibility. Liquid air energy storage (LAES) has emerged as a promising option, where cryogenic energy storage plays a decisive role in round-trip efficiency of the LAES. The traditional method uses axial-flow packed beds to store cryogenic energy, which suffers from large pressure drops, high pumping work consumption and low exergy efficiency. To address the above issues, this paper proposes a novel radial-flow packed bed for a 10 MW/80 MWh LAES system. Systematic analyses are made on the radial-flow packed bed in terms of bed volume, aspect ratio, inner channel ratio, and particle size. Results show that the radial-flow cryogenic packed bed achieves a higher exergy efficiency of 87.7% compared to that of axial-flow packed bed (80.6%). This is because of the much lower pressure drops of radial-flow packed bed (1,173 Pa), where the axial-flow packed bed has a larger pressure drop of 17,186 Pa. Parametric studies further reveal that optimal performance is obtained at 1.5 times the volume of reference bed volume, aspect ratio of 0.1, and inner channel ratios of 0.20–0.25. Particle size reduction enhances heat transfer but significantly increases pressure losses. These findings demonstrate that radial-flow cryogenic packed bed is more energy efficient and applicable for large-scale LAES system.