Compressed air energy storage systems (CAES) have demonstrated the potential for the energy storage of power plants. One of the key factors to improve the efficiency of CAES is the efficient thermal management to achieve near isothermal air compression/expansion processes. This paper presents a review on the Liquid Piston (LP) technology for CAES as a timely documentary on this topic with rapidly growing interests. Various aspects are discussed including the state-of-the-art on LP projects all over the world and the trend of development, the coupled fluid flow and heat transfer during the compression/expansion operations, and different actions proposed and implemented to enhance the heat transfer inside the piston column.

It has been found that LP is a promising concept for isothermal CAES. However, the complex and transient fluid flow and heat transfer behaviors inside the LP are difficult to characterize and master. To enhance the heat transfer and increase the efficiency of the compression/expansion processes many approaches have been tested including liquid spray, wire mesh, porous media, optimal trajectory, hollow spheres and optimal geometry of the piston column. Numerous empirical correlations of Nusselt number have also been proposed to estimate the heat transfer in different types of LP, as reviewed and summarized in this paper.

压缩空气储能系统 (CAES) 已经证明了发电厂储能的潜力。提高 CAES 效率的关键因素之一是实现近等温空气压缩/膨胀过程的有效热管理。本文对 CAES 的液体活塞 (LP) 技术进行了回顾，作为有关该主题的及时纪录片，其兴趣迅速增长。讨论了各个方面，包括世界各地 LP 项目的最新技术和发展趋势，压缩/膨胀操作期间的耦合流体流动和传热，以及为提高热量而提出和实施的不同措施在活塞柱内转移。

已经发现 LP 是等温 CAES 的一个有前景的概念。然而，LP 内部复杂且瞬态的流体流动和传热行为难以表征和掌握。为了增强传热并提高压缩/膨胀过程的效率，已经测试了许多方法，包括液体喷雾、丝网、多孔介质、最佳轨迹、空心球和活塞柱的最佳几何形状。还提出了许多 Nusselt 数的经验相关性来估计不同类型 LP 的传热，如本文所回顾和总结的那样。