Second International Conference on Hydrogen Safety, San Sebastian, Spain, September 2007 CFD for Regulations, Codes and Standards A.G. Venetsanos National Centre for Scientific Research “Demokritos”, Greece A. Kotchourko Research Centre Karlsruhe, Germany C.D. Moen Sandia National Laboratories, US

Slide 2 Presentation Outline  It will be shown that CFD is increasingly applied to provide the necessary support to RCS development: EIHP-2 project HyApproval project HyPer project  It will be shown that CFD tools are increasingly validated against H2 dispersion/combustion phenomena HySafe project  ICHS-2 Session 1 What we are going to see/listen  Venetsanos et al. (ICHS-2, 2007) An Inter-Comparison Exercise On the Capabilities of CFD Models to Predict the Short and Long Term Distribution and Mixing of Hydrogen in a Garage

Slide 3 EIHP2 project:CGH2 bus in a city Taken from Venetsanos et al. (2007) J. Loss Prevention in the Process Industry, In Press Fuel- Pressure (MPa) Energy (MJ) FireballOverpressure Average diameter at 2.0m above ground (m) Maximum diameter at any height above ground (m) Distance to 2kPa overpressure (m) Distance to 21kPa overpressure (m) Distance to 35kPa overpressure (m) H a H a H a CH a 1565LL H2, 20MPa, 10.9s, 12.1 kg LFL clouds Release of 40 kg H2 (168 kg CH4) through 4 outlet vents at the top of the bus (Stockholm accident site) H2, 35MPa, 7.7s, 14.7 kg H2, 70MPa, 5.2s, 18.5 kg CFD applications CH4, 20MPa, 7.9s Bus storage system Urban site (Stockholm) showing assumed bus location

Slide 4 EIHP2 project:CGH2 bus in tunnel Taken from Venetsanos et al. (2007) J. Loss Prevention in the Process Industry, In Press H2, 35MPa, 30s, 2180m 3, 32.5kg H2, 20MPa, 40s, 2358m 3, 32.4kg CH4, 20MPa, 40s, 1756m 3, 110kg FUELPRESSURE (MPa) ENERGY (MJ) FIREBALLOVERPRESSURE Length Along The Tunnel (m) Peak Overpressure (kPa) H a a 150 NG LFL clouds Release of 40 kg H2 (168 kg CH4) through 4 outlet vents at the top of the bus CFD applications

Slide 5 HyApproval project:Examined scenarios  Dispenser: rupture of dispensing line (CGH2 35 and 70 MPa, LH2)  Trailer: Hose disconnection during discharge (CGH2 20 MPa, LH2) CFD applications Luxemburg CGH2 site Washington DC, LH2 site Shell-HSL experimental site (2006) Taken from HyApproval Deliverable 4.6, 2007

Slide 6 HyApproval project:LH2 dispenser leak 267g LH2 released in 5 seconds (hose id = 8mm) CFD applications 5 m/s wind at 10m height Predicted LFL clouds at 5 sec South wind North wind East wind Stagnant West wind Taken from HyApproval, NCSRD-JRC report, 2007

Slide 7 Fuego 3-D RANS simulation of H 2 Jet Flame Wall Impingement Sandia/SRI H 2 Jet Flame Wall Impingement Test (2500 psi) HYPER project:Barrier wall design ●Jet flame experiments are used to validate CFD methodology for jet flames from high-pressure sources. ●CFD calculations are used characterize consequences of unintended releases. ●Barrier walls are a potential mitigation strategy for jet releases. Taken from Houf et al., 2 nd ICHS, 2007 CFD applications

Slide 8 Hyper project:Fuel Cell Leak 14.8g H2 released in 60 seconds CFD applications Fuel cell located inside naturally ventilated test facility Naturally Ventilated Test Facility (CVE) Location and Interior of Fuel Cell

Slide 9 HySafe project:Dispersion CFD benchmarking SBEPDescription Phenomena / Environmental Conditions Low momentu m jets Sonic jets Confinem ent Stratification Natural Ventilation Obstacles Two- phase flow V1 Russian-2, 1988 and 2005  V3INERIS-6C, 2007  V4FZK jets, 2006  V5 GEXCON-D27, 2007  V6 BAM-5, LH2 close to buildings  E1 NASA-6 LH2 in open space  E2Swain Hallway  V10HSL jets  V11 Bus in an underpass QRA exercise GEXCON 

Slide 10 HySafe project: Combustion CFD benchmarking SBEPDescription Phenomena / Environmental Conditions Unconfined combustion Partial confinement/ Venting Complete confinement Slow flames Fast flames Flame acceleration DDT Detonation Scale V2Fh-ICT balloon, 1985  V7 HSL-SHELL HRS tests, 2006  V8FZK tube tests, 2006  V9 Fh-ICT Jet ignition in a lane with DDT, 1984  V12 Tunnel tests, Groethe et al  V13 KI DDT tests hyd5 and hyd9, 1995  V14 Vented explosion Pasman et al, 1974  V15 Bus in an underpass QRA exercise GEXCON  Main parameters important from the point of view of safety analysis:

Slide 11 Conclusions  CFD is increasingly applied for H2 safety studies and RCS support  Main reasons: CFD has the ability to treat complex scenarios, which simpler integral tools cannot handle CFD cost is relatively lower than experiments CFD tools present generally realistic simulation times CFD tools/models are increasingly validated against H2 dispersion/combustion phenomena

Slide 12 ICHS-2 Session-1Contents  CFD applications Analysis of naturally ventilated h2 from buildings, Barley et al. CFD simulations of h2 release and dispersion inside the storage room of a HRS, Papanikolaou and Venetsanos Simulation of detonation after an accidental h2 release in enclosed envirnments, Bιdard- Tremblay et al. CFD simulation study to investigate the risk from h2 vehicles in tunnels, Hansen et al. High pressure h2 jets in the presence of a surface, Benard et al  CFD validation HYSAFE SBEP-V3 results, Venetsanos et al HYSAFE SBEP-V5 results, Jordan et al Validation of CFD calculations against ignited impinging jet experiments, Middha et al. Numerical study of spontaneous ignition of pressurized h2 release into air, Xu et al. CFD modelling of h2 dispersion experiments for SAE J2578 test methods development, Tchouvelev et al.  Experimental work Processes of the formation of large unconfined clouds following a massive spillage of liquid hydrogen on the ground, Proust et al. Experimental study of jet-formed hydrogen-air mixtures and pressure loads from their deflagrations in low confined surroundings, Friedrich et al. Experimental and numerical investigation of h2 Gas Auto-Ignition, Golub et al Unintended Releases of hydrogen, Houf et al