Dynamics of vented hydrogen-air deflagrations J.DAUBECH 1, C. PROUST 1,2, D. JAMOIS 1, E. LEPRETTE 1 1 INERIS, Verneuil en Halatte – France 2 UTC, Compiègne - France

DRA - 14/09/2011 – Vented H2-air deflagrations - 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,...

DRA - 14/09/2011 – Vented H2-air deflagrations - 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

DRA - 14/09/2011 – Vented H2-air deflagrations - 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

DRA - 14/09/2011 – Vented H2-air deflagrations - 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

DRA - 14/09/2011 – Vented H2-air deflagrations - 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

DRA - 14/09/2011 – Vented H2-air deflagrations - 7 Main results – 1 m3 chamber 20% H2 in air Test (20%H2) Classical shape with a single dome Acoustic effect : Fresh gases replaced by burnt gases – local effect External explosion : strong pressure burst and propagation at the speed of sound Acoustic effect : External atmosphere accelerated by the emerging flow of fresh gases End of combustion in the vessel Overpressure keeps on rising when the combustion is ended in the chamber

DRA - 14/09/2011 – Vented H2-air deflagrations - 8 Test (23%H2) End of combustion in the vessel Main results – 10 m3 chamber 23% H2 in air External explosion : Pressure rises sharply before the end of combustion in the tank Pressure decrease First pressure bulge : Combustion in the chamber First acoustic mode of the chamber Natural vibration of metallic envelope

DRA - 14/09/2011 – Vented H2-air deflagrations - 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 Present 1 m3 NFPA 68

DRA - 14/09/2011 – Vented H2-air deflagrations - 10 Next Story...