Numerical Investigation of Hydrogen Jet Dispersion Below and Around a Car in a Tunnel

Nektarios Koutsourakis, Ilias C. Tolias, Stella G. Giannissi () and Alexandros G. Venetsanos
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Nektarios Koutsourakis: Environmental Research Laboratory, INRASTES, National Centre for Scientific Research Demokritos, Patriarchou Grigoriou E & 27 Neapoleos Str., 15341 Agia Paraskevi, Greece
Ilias C. Tolias: Environmental Research Laboratory, INRASTES, National Centre for Scientific Research Demokritos, Patriarchou Grigoriou E & 27 Neapoleos Str., 15341 Agia Paraskevi, Greece
Stella G. Giannissi: Environmental Research Laboratory, INRASTES, National Centre for Scientific Research Demokritos, Patriarchou Grigoriou E & 27 Neapoleos Str., 15341 Agia Paraskevi, Greece
Alexandros G. Venetsanos: Environmental Research Laboratory, INRASTES, National Centre for Scientific Research Demokritos, Patriarchou Grigoriou E & 27 Neapoleos Str., 15341 Agia Paraskevi, Greece

Energies, 2023, vol. 16, issue 18, 1-30

Abstract: Accidental release from a hydrogen car tank in a confined space like a tunnel poses safety concerns. This Computational Fluid Dynamics (CFD) study focuses on the first seconds of such a release, which are the most critical. Hydrogen leaks through a Thermal Pressure Relief Device (TPRD), forms a high-speed jet that impinges on the street, spreads horizontally, recirculates under the chassis and fills the area below it in about one second. The “fresh-air entrainment effect” at the back of the car changes the concentrations under the chassis and results in the creation of two “tongues” of hydrogen at the rear corners of the car. Two other tongues are formed near the front sides of the vehicle. In general, after a few seconds, hydrogen starts moving upwards around the car mainly in the form of buoyant blister-like structures. The average hydrogen volume concentrations below the car have a maximum of 71%, which occurs at 2 s. The largest “equivalent stoichiometric flammable gas cloud size Q9” is 20.2 m 3 at 2.7 s. Smaller TPRDs result in smaller hydrogen flow rates and smaller buoyant structures that are closer to the car. The investigation of the hydrogen dispersion during the initial stages of the leak and the identification of the physical phenomena that occur can be useful for the design of experiments, for the determination of the TPRD characteristics, for potential safety measures and for understanding the further distribution of the hydrogen cloud in the tunnel.

Keywords: hydrogen; CFD; dispersion; safety; tunnel; car; fuel-cell vehicle; TPRD; impinging jet; ADREA-HF; physical parameters; numerical parameters; parametric studies; sensitivity tests; best-practice guidelines (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2023
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