Flame quenching characteristics of porous structures in self-ignition due to high-pressure hydrogen leakage through the tube

초록

Hydrogen gas leaks at high pressures pose a significant risk of self-ignition, potentially leading to flames without an ignition source and secondary damage such as fires and explosions. The rapid spread of hydrogen enhances the likelihood of such incidents. This study examined how a porous structure with narrow channels installed at the vent tube outlet affects the behavior of hydrogen flames. Experiments were conducted at the ejection burst pressure at which self-ignition occurs. The effects of porous structures on self-ignition were investigated using three design parameters: porosity, pattern, and length. The experimental results confirmed the existence of the maximum burst pressure capable of quenching the structure, defined as Pcritical. The quenching types were defined based on the behavior of a flame at the tube exit, considering the pressure difference between Pcritical and the burst pressure and the quenching types were determined for all structures at their respective burst pressures. The burst pressure capable of quenching increased as the length of the porous structures increased, a general effect attributed to the increased internal wetted area as the length increased. The influence of porosity was examined through experiments on honeycomb channel structures designed with four different porosities. The quenching possibility increased as the porosity decreased, but the effect was insignificant below a specific porosity threshold. The effect of the pattern was explored through experiments on honeycomb and lattice structures designed with similar porosities. Even at shorter lengths, the structure with the Octet truss lattice pattern exhibited the best quenching performance at all experimental burst pressures. Hence, the increase in the wetted area of the structure and the influence of the pattern are crucial factors in quenching.

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