Spontaneous Ignition of Cryo-Compressed Hydrogen in a T-Shaped Channel System

Abstract

Sudden releases of pressurised hydrogen may spontaneously ignite by the so-called “diffusion ignition” mechanism. Several experimental and numerical studies have been performed on spontaneous ignition for compressed hydrogen at ambient temperature. However, there is no knowledge of the phenomenon for compressed hydrogen at cryogenic temperatures. The study aims to close this knowledge gap by performing numerical experiments using a computational fluid dynamics model, validated previously against experiments at atmospheric temperatures, to assess the effect of temperature decrease from ambient 300 K to cryogenic 80 K. The ignition dynamics is analysed for a T-shaped channel system. The cryo-compressed hydrogen is initially separated from the air in the T-shaped channel system by a burst disk (diaphragm). The inertia of the burst disk is accounted for in the simulations. The numerical experiments were carried out to determine the hydrogen storage pressure limit leading to spontaneous ignition in the configuration under investigation. It is found that the pressure limit for spontaneous ignition of the cryo-compressed hydrogen at temperature 80 K is 9.4 MPa. This is more than 3 times larger than pressure limit for spontaneous ignition of 2.9 MPa in the same setup at ambient temperature of 300 K.

Cryogenic Hydrogen Jet and Flame for Clean Energy Applications: Progress and Challenges

“…Finally, spontaneous ignition occurs inside the tube and the two combustion regions merge. An additional study on the spontaneous ignition of cryo-compressed hydrogen in a T-shaped channel was carried out by Cirrone, Makarov and Molkov [122]. Cirrone, Makarov and Molkov released a numerical CFD study on the near-field thermal dose resulting from cryogenic hydrogen jet fires in 2019, based on three experiments performed at SNL [123].…”