Abstract: Existing methods and systems for testing the airtightness of sealing layers are inadequate for artificial caverns used in compressed air energy storage (CAES) facilities. This limitation severely hinders the development of these sealing layers. To address this limitation, an airtightness testing system specifically designed for the unique conditions of CAES facilities is developed. The developed system simulates the high-pressure environment typical of these facilities using a high-pressure air compressor, pressure controller, and an airtightness test chamber. Furthermore, the developed system replicates the composite structural characteristics of these facilities with a composite test specimen including a deformation layer, precast concrete ring, and the sealing layer. Two methods are employed to simulate lining crack conditions: (1) pressure-induced expansion and cracking of the composite structure and (2) preset cracks in steel plates. Additionally, a multiparameter monitoring system for pressure, temperature, and flow rate is established to evaluate the airtightness performance and structural stability of the sealing layer. Performance tests are conducted on various candidate sealing materials using this system. The results from these tests reveal the following details: (1) Polyurethane and polyurea materials demonstrate superior high-pressure airtightness and crack-spanning stability; however, they still face risks of material degradation and fatigue failure under long-term cyclic operations. (2) Flexible sealing materials adapt well to the pressure-induced expansion and deformation of air storage caverns; however, they show inadequate stability across cracks. While designing the sealing layer, high-hardness materials should be prioritized or composite structural layers should be incorporated to improve crack stability. (3) The developed system effectively validates the airtightness and stability of the sealing layer, offering reliable experimental support for the research and development of sealing layers for CAES.

Key words: compressed air energy storage, artificial air storage caverns, sealing layer, test system, high-pressure airtightness