2. Context
R&D activities in H2 technologies in France is driven by industrial research targeting real applications (DIMITHRY, H2E, HYPE, ...)
Safety management is the “red line” and especially aiming at shaping mitigation techniques (avoid atex, control fire and explosion effects)
Explosion venting need to be considered :
Widely used in industry,
Large body of experiments,
Theory, standards, guidelines, ...

3. But, … Vent dimensioning remains difficult :
Some key phenomena remain obscure :
The role of flame instabilities
Combustion of external cloud
Interaction internal/external explosion
...
Severe lack of experimental :
... evidence
... data about vented hydrogen explosion
Purpose of this work :
Providing additional results about vented hydrogen-air explosions in vessels of industrial sizes

4. Experimental devices 1 m3 chamber : Length : 1.85 m Diameter : 0.94 m
Vent area : 0.15 m2
10 m3 chamber :
Length : 5.73 m
Diameter : 1.6 m
Vent area : 2 m2

5. Instrumentation 1 m3 chamber :
Injection device : 1 bottle of 5 l (filled with H2)
Pressure : 5 piezoresistive gauges
Inside : 2 gauges – (0-10 bar ± 0.01 bar)
Outside : 3 gauges – (0-2 bar ± bar) installed in lenses supports at 1, 3 and 5 m
Ignition : pyrotechnical match (60 J) opposite to vent
Propagation of the flame : 6 ionisation gauges

6. Instrumentation 10 m3 chamber :
Injection device : 4 bottles of 8 l (filled with H2)
Pressure : 2 piezoresistive gauges
(0-10 bar ± 0.01 bar)
Ignition : pyrotechnical match (60 J) opposite to vent
Propagation of the flame :
4 ionisation gauges
4 optical sensors

7. Main results – 1 m3 chamber
Test (20%H2)
Classical shape with a single dome
End of combustion in the vessel
Overpressure keeps on rising when the combustion is ended in the chamber
External explosion : strong pressure burst and propagation at the speed of sound
Acoustic effect :
Fresh gases replaced by burnt gases – local effect
Acoustic effect :
External atmosphere accelerated by the emerging flow of fresh gases
20% H2 in air

8. Main results – 10 m3 chamber
External explosion : Pressure rises sharply before the end of combustion in the tank
Test (23%H2)
First pressure bulge : Combustion in the chamber
End of combustion in the vessel
First acoustic mode of the chamber
Natural vibration of metallic envelope
Pressure decrease
23% H2 in air

9. Conclusion
Typical industrial question : How do the data compare to the standards ?
Absolute necessity to refine our knowledge of the phenomenology and to produce much more data NEXT STORY
Bauwens et al 64 m3
Pasman et al 1 m3
Kumar et al
6.85 m3
Present
10 m3
1 m3
NFPA 68

10. Next Story...