Numerical investigation on explosion hazards of lithium-ion battery vented gases and deflagration venting design in containerized energy storage system

Large-scale Energy Storage Systems (ESS) based on lithium-ion batteries (LIBs) are expanding rapidly across various regions worldwide. The accumulation of vented gases during LIBs thermal runaway in the confined space of ESS container can potentially lead to gas explosions, ignited by various electrical faults. However, a systematic simulation and assessment of the battery vented gases explosion under deflagration venting design still lack. In this work, a three-dimensional combustion model was developed within the frame of open source computational fluid dynamics code OpenFOAM based on a full-scale container, and the LIBs vented gases in realistic proportion were selected as the combustion gas. Coupled boundary conditions were introduced to enable the response of explosion vent doors and top deflagration vent panels on pressure. The internal and external overpressure, flame temperature, and wind velocity fields were employed to assess the gas explosion hazards to ESS container structure and surroundings. The results demonstrate that altering the vent door pressure, without the top vent panel, still leads to serious explosion accidents. There will be unacceptable overpressure for the container structure, as well as serious visible flames and high-speed airflow invading the external environment. Lower vented gas concentrations can reduce explosion hazards, and introducing the vent panel design aids to promote such reduction. The overpressure within the container is significantly decreased by guiding the top external secondary combustion through the vent panel, and the influence range for the environments is also significantly reduced on X-axis. The ignition location can affect the propagation of gas combustion within the container, and the proposed complete vent panel design minimizes the impact on the container structure and surroundings. The findings of this work can offer new references for the safety design of the LIBs ESS.