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Simulation of the efficiency of hydrogen recombiners as safety devices

Simulation of the efficiency of hydrogen recombiners as safety devices. Ernst-Arndt Reinecke, Stephan Kelm, Wilfried Jahn, Christian Jäkel, Hans-Josef Allelein. International Conference on Hydrogen Safety September 12-14, 2011, San Francisco, CA. Overview.

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Simulation of the efficiency of hydrogen recombiners as safety devices

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  1. Simulation of the efficiency of hydrogen recombiners as safety devices Ernst-Arndt Reinecke, Stephan Kelm, Wilfried Jahn, Christian Jäkel, Hans-Josef Allelein International Conference on Hydrogen Safety September 12-14, 2011, San Francisco, CA

  2. Overview Simulation of the efficiency of hydrogen recombiners as safety devices • Passive auto-catalytic recombiner (PAR) • Goal of the numerical study • Scenario investigated • Model approach • Results

  3. Unintended H2 release inside confined space

  4. Passive auto-catalytic recombiner (PAR)

  5. Commercial PARs in Nuclear Power Plants Vendors • AECL, Canada • AREVA, France/Germany • NIS, Germany Source: Siempelkamp

  6. Operational boundary conditions NPP containment • large temperature and density gradients • large natural convection loops • large geometry (20,000-70,000 m³, typical length scales 5-50 m) • steam-inertized in early accident phase Typical H2 and FC applications • significant smaller scales • different thermal hydraulic conditions PAR applicability ? NPP H2 & FC GOAL:

  7. Scenario

  8. Experiment Source: CEA • GARAGE facility at CEA/France • single vehicle private garage (~40 m³) • concentration measurement at ~60 pos. Test 1: He release (~2 g/s) for ~2 min data recently published:Gupta et al., Int J Hydrogen Energy 34 (2009) 5902–5911

  9. Release scenario and measurement locations

  10. Approach Scenario based on GARAGE experiment (CEA) • Simulation of the helium release and distribution scenario and validation against experimental data • Replace helium by hydrogen and verify the calculated distribution • Add a PAR to the scenario and compare mitigated/unmitigated scenario

  11. Model approach

  12. Coupled Modeling Approach Micro Scale Meso Scale Macro Scale REKO-DIREKT(in-house) ANSYS CFX

  13. Output: T, yi, m natural convection Chimney chemical (catalytical) reaction mass/heat transfer Catalystsection Input: T, yi, p PAR model: REKO-DIREKT

  14. REKO-DIREKT REKO-DIREKT  CFX- Outlet gas temperature- Outlet gas composition- Mass flow through PAR REKO-DIREKT  CFX T / °C yH2 / Vol.-% CFX  REKO-DIREKT- Inlet gas temperature- Inlet gas composition- Pressure

  15. Results

  16. Unmitigated release - setup • Physical Model: • Half Symmetry • RANS equations • Ideal gas equation of state • Isothermal • SST-model incl. buoyancy prod. & dissipation • Injection • He: 240 g (1,99 g/s) • H2: 120 g (0,99 g/s) • Wall functions at inner walls • Vent: Outlet Boundary

  17. Helium/Hydrogen concentration profiles

  18. Mitigated release - setup • Physical Model: • Half Symmetry • RANS equations • Ideal gas equation of state • SST-model incl. buoyancy prod. & dissipation • Injection • H2: 120 g (0,99 g/s) • Wall functions at inner walls • Fixed Wall Temperature • Temperature dependent properties • No heat radiation • Vent: Outlet Boundary

  19. 120 s 240 s 800 s Comparison mitigated/unmitigated scenario

  20. Comparison mitigated/unmitigated scenario

  21. Details mitigated scenario

  22. PAR model details

  23. Flammable cloud volume histories

  24. Performance (estimates) Processor • 1 CPU Quadcore I7-860, 2.8 GHz • Open Suse Linux 11.3 • CFX 12.1 Calculation time (1200 s) • unmitigated scenario: ~10 d • mitigated scenario: ~40 d • REKO-DIREKT: ~6 min • more time steps • more gas components (H2+O2+N2+H2O)

  25. Conclusions

  26. Conclusions (1/2) Goal • investigate the applicability of PAR from NPP containment to typical H2&FC application • significant differences in operational boundary conditions • first study based on GARAGE experiment, performed with ANSYS-CFX and REKO-DIREKT Results • H2 injection of 1.5 m³, flammable cloud was removed within 10 minutes • hot exhaust plume promotes the transport of hydrogen rich gas mixture towards the PAR inlet

  27. Conclusions (2/2) Next steps • parameter variation • injection rate, location, and direction • PAR design and number • geometry of the enclosure • consideration of possible PAR ignition scenarios • validation against mitigation experiments in new multi-compartment facility, currently under construction at JÜLICH

  28. Thank you for your attention !

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