Figure 1
Hydrogen source definitions: blowdown hydrogen mass flow rates decaying along time, corresponding to thermally activated pressure relief device (TPRD) diameters of 1.37 mm, 1.94 mm, and 2.74 mm, respectively.
Figure 2
Tunnel geometrical model with adaptive mesh scheme with locations of hydrogen release and water injection.
Table 1
Simulation cases with variant hydrogen release rates, mass flow rates of spray water, and spray droplet sizes.
| WATER SPRAY | NO SPRAY | ||||||
|---|---|---|---|---|---|---|---|
| SMALL MASS FLOW RATE OF WATER (1.34 kg/s) | LARGE MASS FLOW RATE OF WATER (2.74 kg/s) | ||||||
| SMALL DROPLET (100 µm) | MEDIUM DROPLET (200 µm) | LARGE DROPLET (300 µm) | SMALL DROPLET (100 µm) | MEDIUM DROPLET (200 µm) | LARGE DROPLET (300 µm) | ||
| Small mass flow rate of H2 (max. 0.05 kg/s) | sss | ssm | ssl | sls | slm | sll | alpha |
| Large mass flow rate of H2 (max. 0.1 kg/s) | lss | lsm | lsl | lls | llm | lll | beta |
| Very large mass flow rate of H2 (max. 0.2 kg/s) | xlss | xlsm | xlsl | xlls | xllm | xlll | epsilon |
Figure 3
Velocity vector and spray droplet distribution in the computational domain of tunnel in case of initial max. 0.2 kg/s H2 release rate and 1.34 kg/s water spray with 100 μm droplet (Case ‘xlss’) during 2–3 s.
Figure 4
Temperature contour plots in a longitudinal vertical cut of tunnel through TPRD nozzle at different times in the case of initial max. 0.1 kg/s H2 release rate and 2.74 kg/s water spray with 100 μm droplet (Case ‘lls’).
Figure 5
Average gas temperatures in the downstream region (a), and at tunnel exit (b), in case of 0.05 kg/s H2 release rate without and with spray of different droplet sizes.
Figure 6
Average gas temperatures in the downstream region in case of 0.2 kg/s H2 release rate without and with spray of different water mass flow rate: (a) whole view; (b) zoomed view during 0–5 s, showing the intensified turbulence effect caused by spray.
Figure 7
Average absolute humidity in tunnel atmosphere: (a) small H2 release rate (0.05 kg/s); (b) very large H2 release rate (0.2 kg/s), without and with spray of different water mass fluxes.