The Fire Tests with High-Pressure Hydrogen Gas Cylinders for Evaluating the Safety of Fuel-Cell Vehicles

The high-pressure hydrogen gas cylinder of a fuel-cell vehicle is equipped with a pressure relief device (PRD) to prevent the rupture of the cylinder due to heating by fire. Flame exposure tests (bonfire tests) are conducted to evaluate the safety of the cylinder with the PRD, specifically, cylinder resistance to fire and performance of the PRD. In this study, however, fire tests of vehicles equipped with high-pressure cylinders were not required for this test method.

We implemented released-hydrogen flame tests by performing bonfire tests and fire tests on vehicles equipped with hydrogen-filled high-pressure gas cylinders (20,35MPa) to examine safety measures for fuel-cell vehicles. We then investigated the following: the characteristics of the released-hydrogen flame, radiation heat flux from the jet flame, combustion noise, the rate of pressure rise in the cylinder, the venting direction of the PRD, and behavior of fire in conjunction with a gasoline flame. The results demonstrate that it is necessary to specify the venting direction of the PRD, as well as the details of the shielding for PRD to be used to prevent direct flame impingement.