Transient fire response and cooling strategy evaluation for a vehicle-mounted hydrogen cylinder

Thanking to zero carbon emission, hydrogen is regarded as a promising energy carrier in the future, but its use in city is still limited due to explosion risk. Typically, traffic accident poses unpredictable danger for hydrogen use in vehicle, but time-dependent evolutions of hydrogen cylinder at accidental fire conditions remain unclear. Here, a three-dimensional discrete vehicle-mounted hydrogen cylinder is established, and the distributions of temperature and stress are determined. Results show that heat accumulation is the main reason for fast temperature rise. Specifically, when fire occurs both on the side wall and bottom, the time of material-yielding explosion can be as short as 245 s. The explosion time is affected by fire source location, fire-affected area and ambient temperature, which emphasizes the necessity of cooling exertion. A later cooling operation leads to a higher cooling capacity requirement, while the relationship between cooling-starting temperature and cooling capacity demand shows a progressively steeper trend. If appropriate cooling is adopted, the escape time for passengers can be extended to over 190%. Sampling point location and alerting temperature are explained as key factors for cooling strategy design, while the advances of this study are also revealed by comparison with existing researches. The results of this study contribute to: 1) providing a time-dependent evolution scheme for a fire-suffered hydrogen cylinder; 2) developing monitoring and protection of hydrogen-related equipment; 3) promoting the realization of smart city with hydrogen utilization.