Re-enacting the Hydrogen Tank Explosion of a Fuel-cell Electric Vehicle: An Experimental Study

With the world-wide decision to reduce carbon emissions through the Paris Agreement (2015), the demand for hydrogen-fuelled vehicles has been increasing. Although hydrogen is not a toxic gas, it has a wide flammable range (4e75%) and can explode due to static electricity. Therefore, studies on hydrogen safety are urgently required. In this study, an explosion was induced by applying fire to the lower part of a fuel cell electric vehicle (FCEV). Out of three compressed hydrogen storage tanks installed in the vehicle, two did not have hydrogen fuel, and one was filled with compressed gaseous hydrogen of 700 bar and forcedly deactivated its temperature-activated pressure relief device. The side-on overpressure transducers were installed by distance in main directions to measure the side-on overpressure generated by the vehicle explosion. A 10 m-long protective barrier was installed, on which reflected overpressure, displacement, and acceleration were measured to examine the effect of attenuation of explosion damage in the event of an accident. The vehicle exploded approximately 11 min after ignition, generating a blast wave, fireballs, and fragments. The results of the experiment showed that the protective barrier could almost completely block explosive pressure, smoke, and scattering generated during an explosion. Through Probit function analysis, the probabilities of an accident occurring were derived based on peak overpressure, peak impulse, and scattering. The results of this study can be used to develop standard operating procedures (SOPs) for firefighters as the base data for setting the initial operation location and deriving the safe separation distance.