Experimental investigation on the thermal performance of a 28-kWh novel packed-bed cryogenic energy storage platform

Recent years have witnessed growing interest in cryogenic energy storage (CES) technology owing to its potential for enabling energy cascade utilization, reducing carbon emissions, and facilitating low-temperature industrial processes. Packed bed CES systems emerge as particularly promising solutions given their operational reliability, environmental compatibility, and cost efficiency. However, experimental research on pilot-scale implementations remains scarce, with critical knowledge gaps persisting regarding dynamic response characteristics under practical operating conditions. To bridge this research void, this study pioneers the design and construction of a first-of-its-kind 28 kWh total-capacity packed bed CES experimental platform. Using limestone as the cold storage material and gaseous nitrogen at − 155 °C and 0.85 MPa as the cooling source, the system undergoing comprehensive performance testing across charging, static thermal holding, and discharging phases. Results demonstrate that when the discharge cut-off temperature is set to − 110 °C—representative of liquid air energy storage applications—the single-cycle energy efficiency reaches 34.2%. Further increasing the discharge threshold to − 35 °C to emulate low-temperature demands such as cryogenic CO₂ capture and cold-chain logistics, raises the energy efficiency to 72.0%. The experimental results deliver critical experimental datasets supporting structural optimization and industrial deployment of packed-bed CES systems.