1. ICHS-4, 12-15 Sept. 2011, San Francisco, USA A.G.Venetsanos 1, I. Tolias 1, D. Baraldi 7, S. Benz 5, B. Cariteau 2, J. Garcia 3, O.R. Hansen 4, C. Jäkel 6, S. Ledin 8, P. Middha 4, E.A. Papanikolaou 7 1 Environmental Research Laboratory, National Centre for Scientific Research Demokritos (NCSRD), 15310 Aghia Paraskevi, Attikis, Greece, venets@ipta.demokritos.grvenets@ipta.demokritos.gr 2 C.E.A. Saclay, D.E.N., D.M.2S., S.F.M.E., Laboratoire dEtude Expérimentale des Fluides, 91191 Gif/Yvette cedex FRANCE 3 Escuela Técnica Superior de Ingenieros Industriales, Universidad Politécnica de Madrid (UPM), José Gutiérrez Abascal, 2, E-28006 Madrid, Spain 4 GEXCON AS, Fantoftvegen 38 Box 6015 Postterminalen N-5892 BERGEN Norway 5 IKET, KIT, Postfach 3640, 76021 Karlsruhe, Germany 6 Forschungszentrum Juelich (FZJ), 52425 Juelich, Germany 7 Joint Research Centre of the European Commission (JRC), Institute for Energy, 1755 ZG Petten, The Netherlands 8 Health and Safety Laboratory (HSL), Harpur Hill, Buxton, Derbyshire, SK17 9JN, UK IA-HySafe Standard benchmark exercise SBEP-V21: Hydrogen release and accumulation within a non-ventilated ambient pressure garage at low release rates

2. ICHS-4, 12-15 Sept. 2011, San Francisco, USA CONTENTS Introduction & Scope Description of CEA Garage Test 5 Modelling strategy Results & discussion Conclusions 2

3. ICHS-4, 12-15 Sept. 2011, San Francisco, USA Intro & Scope The Research Committee activities of IA- HySafe include: the continuation of SBEPs first introduced within HySafe EC-NoE SBEPs to validate, inter-compare and further develop existing Computational Fluid Dynamics (CFD) codes and models in predicting hydrogen related release, dispersion and combustion phenomena Focus in the present work: Understanding and prediction of the dispersion / accumulation of hydrogen releases in confined spaces under low release conditions 3

4. ICHS-4, 12-15 Sept. 2011, San Francisco, USA CEA Garage Test-5 4 Garage x-dimension (mm)5760 Garage y-dimension (mm)2960 Garage z-dimension (mm)2420 x release (mm)-2880 y release (mm)1480 z release (mm)220 Exit diameter (mm)29,7 Volumetric flow rate - STP (NL/min) 18 He mass flow rate (g/s)0,054 Garage Temperature T (°C)24,1 Exit velocity (m/s)0,47 Release DirectionUpwards Release TypeContinuous Release duration (s)3740 Released volume - STP (NL)1122 He released mass (gr)200,28 Target concentration (%)2,94% Total measurement time (s)90440 Re = 115

5. ICHS-4, 12-15 Sept. 2011, San Francisco, USA Modelling strategy 5 Participa nt/ Code Turbule nce model Number of computational cells Convective terms Transient terms Vent model Molecular diffusivity (m 2 /s×10 -5 ) FZJ/CFXSAS-SST 212272 (half garage) 2 nd order 2nd order backwards Euler Opening8.0 GEXCON/ FLACS k-ε Release: 30888 Diffusion: 4560 2 nd orderOpening2.0 GEXCON_ revised/ FLACS k-ε Release: 44352 Diffusion: 7200 2 nd orderExtension2.0 HSL/CFXSST88840 High resolution scheme (2 nd order) 2nd order backwards Euler Opening1.86 JRC/CFXLaminar Release: 101401 Diffusion: 70429 Outside: 5173 2 nd order 2nd order backwards Euler 2 m × 3 m × 3 m extension 11.7 KIT/ GASFLOW k-ε58905 Upwind 1rst order ALE schemeOpening7.5 NCSRD/ ADREA- HF k-ε 53760 Outside: 3360 SMART 3 rd order 1rst order fully implicit 1 m × 2.96 m × 2.42 m extension 5.65 UPM/ FLUENT Laminar1255162 nd order 1rst order fully implicit Opening5.65 UPM_revi sed/ FLUENT Laminar- 1 m × 2.96 m × 2.42 m extension 5.65

6. ICHS-4, 12-15 Sept. 2011, San Francisco, USA Results – Mass balance 6

7. ICHS-4, 12-15 Sept. 2011, San Francisco, USA Results – CPU times 7 Participant/ Code CompressibilitySimulated period (s) CPU time Threads Computer type FZJ/CFX Fully compressible 20000 s15d, 21h3Intel i7 860 CPU GEXCON/ FLACS Low Mach100000 s1d1 Linux-PC, Intel Xeon W3550, 3.07 GHz GEXCON_rev ised/ FLACS Low Mach20000 s5.5h4Quad core HSL/CFX Fully compressible 15000 s (coarse mesh) 12000 s (fine) 18d, 5h (coarse) 19d, 15h (fine) 2 Windows XP SP3 64- bit, 2 Intel Xeon JRC/CFX Fully compressible 15000 s9d, 20h83.25 GHz KIT/ GASFLOW Low Mach200002d, 15h1 Suse Linux 11.2, i7- 950, 3.06GHz NCSRD/ ADREA-HF Fully compressible 708010d2 Windows 7, i7 M620 CPU at 2.67 GHz UPM/ FLUENT Fully compressible 2000013d4 Windows 7, 2 Intel Xeon Quad Core CPUs at 2.4 GHz

8. ICHS-4, 12-15 Sept. 2011, San Francisco, USA Results - Concentrations 8 Sensor namez (mm) P1N32370 P1N22135 P1N11900 M1N51575 M1N41260 M1N3945 M1N2630 M1N1315

9. ICHS-4, 12-15 Sept. 2011, San Francisco, USA Results - Concentrations 9 P1N3, z = 2.37 m

10. ICHS-4, 12-15 Sept. 2011, San Francisco, USA Results - Concentrations 10 P1N2, z = 2.135 m

11. ICHS-4, 12-15 Sept. 2011, San Francisco, USA Results - Concentrations 11 P1N1, z = 1.9 m

12. ICHS-4, 12-15 Sept. 2011, San Francisco, USA Results - Concentrations 12 M1N5, z = 1.575 m

13. ICHS-4, 12-15 Sept. 2011, San Francisco, USA Results - Concentrations 13 M1N4, z = 1.26 m

14. ICHS-4, 12-15 Sept. 2011, San Francisco, USA Results - Concentrations 14 M1N3, z = 0.945 m

15. ICHS-4, 12-15 Sept. 2011, San Francisco, USA Results - Concentrations 15 M1N2, z = 0.63 m

16. ICHS-4, 12-15 Sept. 2011, San Francisco, USA Results - Concentrations 16 M1N1, z = 0.315 m

17. ICHS-4, 12-15 Sept. 2011, San Francisco, USA CONCLUSIONS Relatively good predictions of He concentrations Significant reduction in CPU time with low Mach number solvers Significant effect of extending the computational domain far enough beyond the confined space opening.

18. ICHS-4, 12-15 Sept. 2011, San Francisco, USA THANK YOU FOR YOUR ATTENTION ANY QUESTIONS