Self-ignited flame behavior of high-pressure hydrogen release by rupture disk through a long tube.

Accelerated adoption of hydrogen gas for energy storage requires improved safety for hydrogen storage. In particular, control of self-ignition of hydrogen vented through tubes by pressure relief devices (overpressure protection devices), such as rupture disks, is needed. We clarify the process of self-ignition in tubes of various lengths during venting of high-pressure hydrogen and observe flame behavior at the tube exit. The importance of distance from the rupture disk for flame front evolution is revealed. Specifically, in a tube longer than a critical value, the self-ignited flame undergoes a quenching process, possibly due to steam formation, before it exits the tube. A tube that is too short does not give the gas sufficient time for hydrogen and air mixing to initiate self-ignition. Finally, at slightly longer tube lengths, the hydrogen ignites, but the flame does not fully develop before it exits, and the vortex formed by expanding gas extinguishes it. • Examined self-ignition in high-pressure hydrogen jet owing to diaphragm rupture. • Visualization of flame growth behavior in a tube. • Visualization of flame behavior out of a tube. • The longer a tube, the more flames develop in the tube. • When a flame develops in a tube, a jet flame is more likely to form outside the tube. [ABSTRACT FROM AUTHOR]