CFD Dispersion Simulations of Compressed Hydrogen Releases through TPRD Inside Scaled Tunnel

To achieve the net zero carbon emissions goals by 2050 the transition to cleaner forms and carriers of energy, should be accelerated without though jeopardizing the public safety. Although hydrogen has been deemed to play significant role in the energy transition for years now, there are still concerns for its risks that hamper its widespread implementation in several applications, like for instance automobile applications. Hydrogen-powered vehicles raise concerns about their safety, especially inside confined spaces like tunnels, and thus research on that topic has been intensified during the last years. In this context, experiments have been conducted by UK HSE within the EU-funded project, HyTunnel-CS to examine hydrogen dispersion and deflagration inside a scaled tunnel resulting from fuel cell car, bus and train release.
In this work that was also carried out within the HyTunnel-CS, we present the Computational Fluid Dynamics (CFD) simulations of the HSE unignited experiments. Blowdown tests related to high-pressure hydrogen releases through Thermal Pressure Relief Device (TPRD) installed in car and in train were modeled using the ADREA-HF code. The scope of these simulations was two-fold: a) contribute to the design of the experiments (e.g. indicate sensor positioning, ignition point, etc.) and the interpretation of hydrogen behavior and b) validate the CFD code. For the former, pre-test simulations preceded the experiments to provide design recommendations. When the experiments were conducted the measurements were used for the code validation. Overall, the CFD results are in satisfactory agreement with the experiments. Finally, simulations with different ventilation rates and with model vehicles inside the tunnel were conducted to examine their effect on mixture dispersion and tunnel safety.