Experimental and modeling investigation of critical slugging behavior in marine compressed gas energy storage systems

Document Type


Publication Date


Publication Title

Journal of Energy Storage




Compressed gas energy storage, Hilly-terrain pipe, Liquid accumulation, Slug flow, Zero net liquid flow


As a flexible-scale energy storage technology, underwater compressed gas energy storage is an emerging enabler of the transition to renewable and sustainable energy structure. Liquid accumulation often occurs in the process of underwater pipeline gas transmission, posing a challenge that must be overcome. In this study, an experimental investigation is presented to investigate the flow characteristics of liquid in a hilly-terrain tube with zero net liquid flow. By adjusting the gas velocity, pipe inclination, liquid accumulation volume, and measuring the expansion length of the liquid film in the horizontal pipe, the liquid accumulation movement is divided into three development stages, which are related to the emergence of the liquid slug. The liquid slug in the pipe is moved by absorption, consolidation, and outflow. The movement of the liquid slug is captured by a high-speed camera, and the formation mechanism of the liquid slug is divided into three categories. When the gas flow rate is low, a liquid slug is formed due to wave growth and convective extrusion. The liquid slug produced by wave merging occurs when the gas velocity is high. A theoretical model of the slugging velocity is established. The relationship between maximum growth factor, liquid film thickness, and gas velocity is analyzed. Furthermore, the critical slugging velocity is determined. The model predictions agreed with the experimental measurement results, with a maximum error of less than 10%. This work can help in furthering underwater compressed air energy storage technology.