Abstract: This study addresses the prevention and control requirements of electric vehicle fires by using FDS software to construct a numerical model. Three scenarios were established: no suppression with water mist, overhead water mist application, and water mist wall suppression. The study investigates the heat release rate, smoke diffusion, and temperature field changes of fires caused by thermal runaway of lithium-ion batteries under different water mist isolation and suppression measures. Results indicate that without water mist suppression, the maximum temperature can reach 1 138 °C, with a peak heat release rate of 8.4 MW. Water mist fire suppression systems and water mist walls can effectively inhibit lithium battery thermal runaway. After applying water mist, the overall temperature is controlled within 200 °C, effectively preventing the spread of fire and reducing the impact on surrounding vehicles and facilities. This study analyzes the effectiveness of water mist in controlling lithium battery thermal runaway, verifying its role in reducing fire intensity, delaying fire development, and protecting the surrounding environment. The findings provide data support for optimizing the design and application of water mist fire suppression systems in electric vehicle fires.

Key words: electric vehicles, thermal runaway, isolation and mitigation, numerical simulation, fire prevention and control