Second International Conference on Hydrogen Safety, San Sebastian,
Spain, 11-13 September 2007
CFD for Regulations, Codes and Standards
A.G. VenetsanosNational Centre for Scientific Research “Demokritos”, Greece
A. KotchourkoResearch Centre Karlsruhe, Germany
C.D. MoenSandia 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)
Fireball OverpressureAverage 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)
H2-20 1460 12.7 a 18.8 75 7 3H2-35 1760 10.5 a 15 91 8 3H2-70 2220 16.0 a 21.5 100 9 5
CH4-20 754 11.0 a 15 65 L L
H2, 20MPa, 10.9s, 12.1 kg
LFL cloudsRelease 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, 2180m3, 32.5kg
H2, 20MPa, 40s, 2358m3, 32.4kg
CH4, 20MPa, 40s, 1756m3, 110kg
FUEL PRESSURE (MPa)
ENERGY (MJ)
FIREBALL OVERPRESSURELength Along The
Tunnel (m)Peak Overpressure
(kPa)
H220 3890 220a 42.535 3900 285a 150
NG 20 5380 198 45
LFL cloudsRelease 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 heightPredicted LFL clouds at 5 sec
South wind North wind
East wind
Scenario DL8
0
1
2
3
4
5
0 1 2 3 4 5time (s)
Max
ver
tica
l dis
tan
ce o
f L
FL
fr
om
so
urc
e (m
)
D5 EastD5 WestD5 SouthD5 NorthStagnant
Scenario DL8
0
5
10
15
20
0 1 2 3 4 5time (s)
Max
ho
rizo
nta
l dis
tan
ce o
f L
FL
fro
m s
ou
rce
(m)
D5 EastD5 WestD5 SouthD5 NorthStagnant
StagnantWest wind
Taken from HyApproval, NCSRD-JRC report, 2007
Slide 7
Fuego 3-D RANS simulation of
H2 Jet Flame Wall ImpingementSandia/SRI H2 Jet Flame
Wall Impingement Test (2500 psi)
625
- 625
X (cm)
Z (cm)767.3
0
Y (cm)
-122
625
Barrier
Jet Exit (0,0,0)
Symmetry Plane(Side)
Open Boundaries(Top and Sides)
No Slip Boundary(Bottom)
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., 2nd 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
SBEP Description
Phenomena / Environmental Conditions
Low momentu
m jets
Sonic jets
Confinement
StratificationNatural
VentilationObstacles
Two-phase flow
V1Russian-2, 1988
and 2005
V3 INERIS-6C, 2007
V4 FZK jets, 2006
V5GEXCON-D27,
2007
V6BAM-5, LH2
close to buildings
E1NASA-6 LH2 in
open space
E2 Swain Hallway
V10 HSL jets
V11
Bus in an underpass QRA
exercise GEXCON
Slide 10
HySafe project: Combustion CFD benchmarking
SBEP Description
Phenomena / Environmental Conditions
Unconfined
combustion
Partial confinement/
Venting
Complete confinement
Slow flames
Fast flamesFlame
acceleration
DDTDetonation
Scale
V2 Fh-ICT balloon, 1985
V7HSL-SHELL HRS
tests, 2006
V8 FZK tube tests, 2006
V9Fh-ICT Jet ignition in a lane with DDT, 1984
V12Tunnel tests, Groethe
et al. 2005
V13KI DDT tests hyd5
and hyd9, 1995
V14Vented explosion
Pasman et al, 1974
V15Bus 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-1 Contents 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
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