Large-Scale Testing: Part II

Transcription

1 Large-Scale Testing: Part II Mark Groethe Poulter Laboratory SRI International Menlo Park, CA USA 3rd ESSHS July 2008 University of Ulster Belfast, UK

2 Outline Experiments Large Release Confined Explosions Summary 2

3 Release Experiments 3

4 Hydrogen Release Experiments Tests have been performed to simulate largeand small-scale hydrogen accidents. Tests involve rapidly releasing and igniting large amounts of hydrogen over a relatively short period of time. Tests have been performed to study the blast and thermal radiation produced by the ignition of high-pressure hydrogen releases. Release rates are designed to match the release from a rupture of hydrogen storage facilities and vehicles. Tests have been done to study the interaction of jets with barrier walls. Visibl IR e IR U V R. Schefer, W. Houf, B. Bourne, and J. Colton, Experimental measurements to characterize the thermal and radiation properties of an open flame hydrogen plume, 15 th NHA Meeting, Los Angeles, CA, April

5 Flame Length Ratio Flame Length Ratio L UV /L IR Luv/LIRave_time_HV_04/03.qpa Horizontal Jet Vertical Jet The ratio L UV /L IR is comparable in horizontal and vertical flame orientations. At early blow-down times UV flame lengths are shorter At later blow-down times UV and IR flame lengths are comparable Time (sec) R. Schefer, W. Houf, B. Bourne, and J. Colton, Experimental measurements to characterize the thermal and radiation properties of an open flame hydrogen plume, 15 th NHA Meeting, Los Angeles, CA, April

6 Flame Width-to-Length Ratio Flame Width-to-Length Ratio W IR / L IR WIR/LIR_time_HV_04/03.qpa Horizontal Jet Vertical Jet (0 deg) Vertical Jet (90 deg) 0.17 Flame width-to-length ratio for H2 flames is 0.17 and is independent of flow rate and jet diameter. The value W IR /L IR = 0.17 agrees well with literature values for a range of fuels, jet diameters, and flow rates Time (sec) R. Schefer, W. Houf, B. Bourne, and J. Colton, Experimental measurements to characterize the thermal and radiation properties of an open flame hydrogen plume, 15 th NHA Meeting, Los Angeles, CA, April

7 Visible Flame Length Visible Flame Length L vis (mm) Lvis_mdot_lit.qpa2 : Lvis=0.89*LIR Kalghatgi: d=5.0 mm Kalghatgi: d=8.3 mm Kalghatgi: d=10.0 mm Present study: d=7.94 mm Present study: d=7.94 mm Horizontal jet d=10.0 mm d=8.3 mm Vertical jet Kalghatgi (1984) used flame photographs (1/30 sec exposure) to quantify average distance between jet exit and visible flame tip. Flame length increases with mass flow rate. Flame length increases with jet diameter d=5.0 mm Flame lengths for H 2 shown in plot. Results for methane, propane, and ethylene are similar. m (g/s) R. Schefer, W. Houf, B. Bourne, and J. Colton, Experimental measurements to characterize the thermal and radiation properties of an open flame hydrogen plume, 15 th NHA Meeting, Los Angeles, CA, April

8 Visible Flame Visible Length Flame Length Relative importance of jet momentum flux and buoyancy is given by the flame Froude Number (Delichatsios, 1993) Fr f = u e f s 1.5 / [ ( e / inf ) 0.25 T f /T inf g d J ) ] Define dimensionless flame length L* = L f f s / d J ( e / inf ) 0.5 Dimensionless flame length is a function of Fr f and L * = 13.5 Fr f 0.4 / (1+0.07Fr f2 ) for Fr f < 5 L * = 13.5 for Fr f > 5 R. Schefer, W. Houf, B. Bourne, and J. Colton, Experimental measurements to characterize the thermal and radiation properties of an open flame hydrogen plume, 15 th NHA Meeting, Los Angeles, CA, April

9 Visible Flame Length Visible Flame Length 100 L*_vs_Fr.qpa2 Fr f = > 0 in natural convection limit Fr f = > in convective limit L* = 23 for Fr f > 5 L* = 13.5 Fr f 0.4 / (1+0.07Fr f2 ) 0.2 for Fr f < 5 L* L* 10 Flame length increases with Froude Number Nondimensional flame lengths correlate well for a variety of fuels CH4 C3H8 H2 SRI Flame Barlow Flame Lab Flame Theory Fr Fr R. Schefer, W. Houf, B. Bourne, and J. Colton, Experimental measurements to characterize the thermal and radiation properties of an open flame hydrogen plume, 15 th NHA Meeting, Los Angeles, CA, April L* should not exceed a value of 23. We need to determine jet exit conditions. 9

10 D D D D Radiometer Locations: Plume Tests Radiometer Locations: Plume Tests 10 Schmidt-Boelter-type heat flux transducers with ZnSe windows 6 longitudinal measurements at 2-ft intervals from nozzle 4 radial measurements 8 ft upstream of nozzle exit R1 R2 R R D D D D D D R6 R5 R1 R2 R3 R4 R. Schefer, W. Houf, B. Bourne, and J. Colton, Experimental measurements to characterize the thermal and radiation properties of an open flame hydrogen plume, 15 th NHA Meeting, Los Angeles, CA, April

11 Flame Radiant Power Is Calculated Using Single Heat Flux Measurement C* Siv&Gore_Fig2.qpa Fuel S (kw) C2H C2H CH CH C2H C2H2 56.5i C*(x/L) = 4 R 2 q rad (x/l) / S rad S rad = total radiative power q rad = radiant flux at position x Experiments show C* is independent of: burner diameter flow rate fuel type radial position C* only depends on axial position x/l vis Sivathanu and Gore (1993) R. Schefer, W. Houf, B. Bourne, and J. Colton, Experimental measurements to characterize the thermal and radiation properties of an open flame hydrogen plume, 15 th NHA Meeting, Los Angeles, CA, April

12 Flame Radiant Flame Radiant Power Power Is Is Calculated Using Single Using Single Heat Heat Flux Flux Measurement vert_prof_med_4/17/03.qpa5 t=5 sec t=20 sec t=40 sec t=60 sec t=70 sec Barlow (d J =3.75 mm) C*(x/L) = 4 R 2 q rad (x/l) / S rad S rad = total radiative power q rad = radiant flux at position x C* Experiments show C* is independent of: burner diameter flow rate fuel type radial position C* only depends on axial position x/l VIS R. Schefer, W. Houf, B. Bourne, and J. Colton, Experimental measurements to characterize the thermal and radiation properties of an open flame hydrogen plume, 15 th NHA Meeting, Los Angeles, CA, April

13 Estimate Radiant Power from Flame Residence Time Radiant Fraction, X rad Turns_vs_SRI/labH2 flames.qpa3 Xr_CO/H2 Xr_CH4 Xr_C3H8 Xr_C2H4 Xr_H2 (SRI Flame) Xr_H2 (Lab Flame) Xr_H2(Barlow Flame Flame residence Time, G (ms) Radiant Fraction X rad = S rad / m fuel H c Flame Residence Time f = (r f W f L f ) / ( 3 r o d J 2 u J ) Flame density, f Flame width, W f Flame length, L f Jet diameter, d j Jet velocity, u j Turns and Myhr (1991) Radiant fraction for H 2 flames comparable to CH 4 flames Sooty hydrocarbon flames have significantly higher X rad R. Schefer, W. Houf, B. Bourne, and J. Colton, Experimental measurements to characterize the thermal and radiation properties of an open flame hydrogen plume, 15 th NHA Meeting, Los Angeles, CA, April

14 Barrier Walls: Effect of Barrier Walls on H 2 Flames Stabilized flame H 2 Jet Flames (a) Barriers have been proposed as a mitigation strategy for unintended releases to reduce separation distances. (b) H 2 (c) Characterize stabilization of H 2 jet flames on barriers. Characterize thermal/structural integrity of barriers. Radiometers Develop correlations for wall heights and wall stand-off distances. [Verify the ability of Sandia Navier-Stokes code (Fuego) to compute hydrogen jet flames and unignited jet concentration.] Combine data and analysis with quantitative risk assessment for barrier configuration guidance. R. Schefer, M. Groethe, W. Houf, and J. Keller, Experimental evaluation of barrier walls for risk reduction of unintended hydrogen releases, 17 th World Hydrogen Energy Conference, Brisbane, Australia, June

15 Schematic of Flow Delivery System Nominal Delivery Pressure at Stagnation Chamber: 140 bar H 2 Cylinder Blowdown Maximum Mass Flow Rate: 0.05 kg/sec Mass Flow Rate (kg/sec) P stag (psi) Time (sec) R. Schefer, M. Groethe, W. Houf, and J. Keller, Experimental evaluation of barrier walls for risk reduction of unintended hydrogen releases, 17 th World Hydrogen Energy Conference, Brisbane, Australia, June

16 Barrier Wall Test Configurations Jet at at Wall Wall Center Center Barrier Wall Jet at Wall Top Jet at Wall Top Barrier Wall Inclined Wall 1 Inclined Wall Barrier Wall H2 Jet H2 Jet 60 degrees H2 Jet Ground Free Jet Free Jet Three-sided Wall 2 Three-sided Wall Barrier Wall H2 Jet 135 degrees H2 Jet Ground 1 Based on NFPA 68 guidelines for barrier walls. 2 Recommended by IFC R. Schefer, M. Groethe, W. Houf, and J. Keller, Experimental evaluation of barrier walls for risk reduction of unintended hydrogen releases, 17 th World Hydrogen Energy Conference, Brisbane, Australia, June

17 Barrier Wall Test Configurations Jet at Wall Center Jet at Wall Top Inclined Wall 1 Three-sided Wall 2 Free Jet 1 Based on NFPA 68 guidelines for barrier walls. 2 Recommended by IFC R. Schefer, M. Groethe, W. Houf, and J. Keller, Experimental evaluation of barrier walls for risk reduction of unintended hydrogen releases, 17 th World Hydrogen Energy Conference, Brisbane, Australia, June

18 Barrier Wall Tests: Temperature Gas temperature for Test 1-07: Jet centered on vertical wall Dashed line indicates free jet measurements Effect of barrier wall on gas temperature is limited to region near wall surface. Heat transfer to wall reduces adjacent gas temperature by nearly 500 K. Barrier Wall 2.4 m x 2.4 m cinderblock wall with jet centered on wall R. Schefer, M. Groethe, W. Houf, and J. Keller, Experimental evaluation of barrier walls for risk reduction of unintended hydrogen releases, 17 th World Hydrogen Energy Conference, Brisbane, Australia, June

19 Barrier Wall Tests: Overpressure Static and reflected pressure for Test 1-07: Jet centered on wall Front of wall Behind wall Overpressure in front of wall exceeds 6 kpa. Barrier wall attenuates pressure by factor of five. 2.4 m x 2.4 m cinderblock wall with jet centered on wall R. Schefer, M. Groethe, W. Houf, and J. Keller, Experimental evaluation of barrier walls for risk reduction of unintended hydrogen releases, 17 th World Hydrogen Energy Conference, Brisbane, Australia, June

20 Barrier Wall Tests Jet centered at top of wall Wall Displacement Jet impacts the wall (pre-ignition) displacement_test1&2.qpa Disp1-07 (in) Displ 2-07 (in) Melted Cinderblock Wall 0.02 Displcement (in) Wall beginsd to tilt from heat loading Melted cinderblock Hz ringoing when blast reaches the wall Cracks Time (sec) R. Schefer, M. Groethe, W. Houf, and J. Keller, Experimental evaluation of barrier walls for risk reduction of unintended hydrogen releases, 17 th World Hydrogen Energy Conference, Brisbane, Australia, June

21 Barrier Wall Tests Stagnation Chamber Igniter Inclined Wall Inclined wall after flame impact Radiometers Equipment setup for inclined wall at SRI test site R. Schefer, M. Groethe, W. Houf, and J. Keller, Experimental evaluation of barrier walls for risk reduction of unintended hydrogen releases, 17 th World Hydrogen Energy Conference, Brisbane, Australia, June

22 Barrier Wall Tests Visible Video Image (early) Visible Video Image (late) Flame extends farther past wall top at early times. Inclined (60-degree) wall with jet centered R. Schefer, M. Groethe, W. Houf, and J. Keller, Experimental evaluation of barrier walls for risk reduction of unintended hydrogen releases, 17 th World Hydrogen Energy Conference, Brisbane, Australia, June

23 Barrier Wall Tests High Speed Video (500 fps) t = sec t = sec t = sec t = sec t = sec t = sec Three-sided wall (135 degrees between sides) R. Schefer, M. Groethe, W. Houf, and J. Keller, Experimental evaluation of barrier walls for risk reduction of unintended hydrogen releases, 17 th World Hydrogen Energy Conference, Brisbane, Australia, June

24 Barrier Wall Tests: Effect on Overpressure Pressure Before Wall Wall-centered jet results in a factor of 2.5 increase in overpressure prior to wall. Overpressure generated by three-sided wall is low at the ignition delay time studied (variable ignition timing could change this). Pressure Attenuation Maximum overpressure reduction was achieved by three-sided wall (pressure behind wall reduced by a factor of 14). R. Schefer, M. Groethe, W. Houf, and J. Keller, Experimental evaluation of barrier walls for risk reduction of unintended hydrogen releases, 17 th World Hydrogen Energy Conference, Brisbane, Australia, June

25 Barrier Wall Tests: Effect on Radiative Heat Flux R 4 (kw/m 2 ) Heat Flux Behind Wall Wall-top jet Inclined wall Test Number R4_vs_Test.qpa t = 25 seconds Wall-center jet Three-side wall Maximum radiative heat flux behind wall occurs with jet at top of wall jet. Heat flux levels with all walls are well below harmful levels. Walls are an effective mitigation strategy for radiative heat flux hazards as long as flame is confined by wall. R 1 (kw/m 2 ) Heat Flux at Jet Origin t= 25 seconds Free jet Wall-top jet Inclined wall R1_vs_Test.qpa Test Number Wall-center jet Three-side wall Walls significantly increase heat flux levels at leak origin. Heat flux levels at leak origin for jet centered on wall exceed pain threshold limit (19.87 kw/m 2 for 2-sec exposure time). R. Schefer, M. Groethe, W. Houf, and J. Keller, Experimental evaluation of barrier walls for risk reduction of unintended hydrogen releases, 17 th World Hydrogen Energy Conference, Brisbane, Australia, June

26 Large Release Experiments Rapid release of a large quantity of hydrogen that is ignited Estimated Flame Jet Sample station Igniters (15mJ) Pressure and heat flux gauges Sample station 18-m tower Sample station Nozzle Description and Summary 300 Nm 3 H 2 (27 kg) are released in about 30 sec. Spontaneous ignition occurs for all experiments. Possible sources could be static discharge, friction heating of particulates, other? Significant overpressures result on ignition Release valve M. Groethe, E. Merilo, J. Colton, S. Chiba, Y. Sato and H. Iwabuchi, Large-scale hydrogen deflagrations and detonations, International Journal of Hydrogen Energy, Volume 32, Issue 13 (September 2007) pp

27 Large Release Experiments High-Speed Video Frames ms ms ms ms ms 18 m Spontaneous ignition M. Groethe, E. Merilo, J. Colton, S. Chiba, Y. Sato and H. Iwabuchi, Large-scale hydrogen deflagrations and detonations, International Journal of Hydrogen Energy, Volume 32, Issue 13 (September 2007) pp

28 Large-Release Test Overpressure Heat Flux Flame Speed M. Groethe, E. Merilo, J. Colton, S. Chiba, Y. Sato and H. Iwabuchi, Large-scale hydrogen deflagrations and detonations, International Journal of Hydrogen Energy, Volume 32, Issue 13 (September 2007) pp

29 Confined Explosion Experiments 29

30 Confined Explosion Experiments Studies of hydrogen release and deflagrations in confined areas Vehicle tunnels and buildings Homogeneous hydrogen-air mixtures and hydrogen releases representing leaks from fuel-cell vehicles and fuel transports Models of vehicles and actual vehicles to investigate turbulent enhancement Passive and active ventilation approaches Tunnel Garage 30

31 Tube Experiments Purpose: Assess confined turbulent combustion Parameters that were varied: Tube Blockage ratio: 0.32, 0.47, & 0.65 Obstacle spacing: 38 cm, 76 cm, & 152 cm H 2 concentration: 20%, 30%, & 57% End conditions, closed or open Mixing tube Tube Closed end Obstacle Open end M. Groethe, J. Colton, and S. Chiba, Hydrogen deflagration safety studies in a confined tube, 14 th World Hydrogen Energy Conference, Montreal, Québec, 9-13 June

32 Tube Sensors Thermocouple Pressure sensor Ion pin Ion probe Obstacle M. Groethe, J. Colton, and S. Chiba, Hydrogen deflagration safety studies in a confined tube, 14 th World Hydrogen Energy Conference, Montreal, Québec, 9-13 June

33 Tube End Conditions Ignition end was closed Output end was opened just prior to ignition by rupturing a tightly stretched latex rubber diaphragm Latex diaphragm Diaphragm ruptured Ignition of mixture M. Groethe, J. Colton, and S. Chiba, Hydrogen deflagration safety studies in a confined tube, 14 th World Hydrogen Energy Conference, Montreal, Québec, 9-13 June

34 Flame Speed, Overpressure, and DDT Turbulence from just a few obstacles produces a transition to detonation (DDT) Obstacle M. Groethe, J. Colton, and S. Chiba, Hydrogen deflagration safety studies in a confined tube, 14 th World Hydrogen Energy Conference, Montreal, Québec, 9-13 June

35 Tunnel Experiments Deflagration, H2 release, obstacle-induced enhancement Two types of experiments: Homogeneous deflagration experiments In-tunnel release experiments Scaled release and ventilation rates ~ 1/5 scale M. Groethe, E. Merilo, J. Colton, S. Chiba, Y. Sato, and H. Iwabuchi, Large-scale hydrogen deflagrations and detonations, International Journal of Hydrogen Energy, Volume 32, Issue 13 (September 2007) pp

36 20% and 30% Hydrogen Experiment 37 m 3 tent Tunnel 20% hydrogen in a 37 m 3 volume 20% H 2 Concrete floor IR 20% 0 ms IR 20% 100 ms Y. Sato, E. Merilo, M. Groethe, J. Colton, S. Chiba, and H. Iwabuchi, Homogeneous hydrogen deflagrations in a sub-scale vehicle tunnel, National Hydrogen Association (NHA) Annual Hydrogen Conference 2006, Long Beach, California, March

37 FC Bus Tunnel Experiments Tunnel - range + range No ventilation, no obstacles Jet ignition occurred, overpressure ~ 0.25 kpa Sample 1 Sample 2 Sample 3 Spark Hydrogen Concentration (%) Sample 1 Sample 2 Sample Range (m) Y. Sato, E. Merilo, M. Groethe, J. Colton, S. Chiba, and H. Iwabuchi, Hydrogen release deflagrations in a sub-scale vehicle tunnel, 16 th World Hydrogen Energy Conference, Lyon, France, June

38 Garage Experiments Evaluate the effects of release rate and ventilation rate on hydrogen concentration. Characterize the resulting flame speed and overpressure when the mixture is ignited. Dimensions - Height: 2.72 m - Width: 3.64 m - Length: 6.10 m - Volume: ~ 60 m m 0.09 m - The open end was covered with sheet of mm high-density polyethylene (HDPE) for the tests. - This allowed visible and infrared cameras to capture images of the flame. - A ventilation intake hole was cut at the bottom of the plastic sheet. Y. Ishimoto, E. Merilo, M. Groethe, S. Chiba, H. Iwabuchi, and K. Sakata, Study of hydrogen diffusion and deflagration in a closed system, 2 nd International Conference on Hydrogen Safety (ICHS), San Sebastian, Spain, September

39 Garage Instrumentation Thermocouples Sample Stations P2 X P4 P1 Z Sample Stations Y Ventilation Exhaust Duct P3 Release Nozzle Release Point Y. Ishimoto, E. Merilo, M. Groethe, S. Chiba, H. Iwabuchi, and K. Sakata, Study of hydrogen diffusion and deflagration in a closed system, 2 nd International Conference on Hydrogen Safety (ICHS), San Sebastian, Spain, September

40 Hydrogen Concentration c 20 The maximum concentration is proportional to the ratio of the hydrogen release rate and the ventilation rate within the range of parameters tested in the present study. Therefore, a required ventilation rate can be estimated from the assumed hydrogen leak rate within the present experimental conditions. Further experiments in closed systems are necessary, varying additional parameters (volume, the direction of the nozzle, ). n e g d r y h Maximum H 2 concentration m u m i x a M The The ratio ratio of of hydrogen release rate to to ventilation ventilation speed speed The correlation between the ratio of the hydrogen release rate to ventilation rate and the maximum hydrogen concentration Y. Ishimoto, E. Merilo, M. Groethe, S. Chiba, H. Iwabuchi, and K. Sakata, Study of hydrogen diffusion and deflagration in a closed system, 2 nd International Conference on Hydrogen Safety (ICHS), San Sebastian, Spain, September

41 Summary Open Space Experiments Assess scaling effects, acquire free-field blast data Open Space with Obstacles Small-scale obstacles have shown significant enhancement of explosions Large-scale obstacles have not significantly enhanced explosions Protective Blast Wall Experiments Reduction in overpressures behind the walls Large Release Experiments Spontaneous ignition Confined Explosions DDT with only a few obstacles in the small tube Significant enhancement of explosions Ventilation has been successful at mitigating the risk 41

42 References R. Schefer, M. Groethe, W. Houf, and J. Keller, Experimental evaluation of barrier walls for risk reduction of unintended hydrogen releases, 17 th World Hydrogen Energy Conference, Brisbane, Australia, June E. Merilo and M. Groethe, Deflagration safety study of mixtures of hydrogen and natural gas in a semi-open space, 2 nd International Conference on Hydrogen Safety (ICHS), San Sebastian, Spain, September Y. Ishimoto, E. Merilo, M. Groethe, S. Chiba, H. Iwabuchi, and K. Sakata, Study of hydrogen diffusion and deflagration in a closed system, 2 nd International Conference on Hydrogen Safety (ICHS), San Sebastian, Spain, September M. Groethe, E. Merilo, J. Colton, S. Chiba, Y. Sato, and H. Iwabuchi, Large-scale hydrogen deflagrations and detonations, International Journal of Hydrogen Energy, Volume 32, Issue 13 (September 2007) pp E. Merilo, M. Groethe, J. Colton, and S. Chiba, Experimental facilities for large-scale and full-scale study of hydrogen accidents, Hydrogen & Fuel Cells 2007: International Conference and Trade Show, Vancouver, Canada, 29 April - 2 May Y. Sato, E. Merilo, M. Groethe, J. Colton, S. Chiba, and H. Iwabuchi, Hydrogen release deflagrations in a sub-scale vehicle tunnel, 16 th World Hydrogen Energy Conference, Lyon, France, June Y. Suwa, H. Miyahara, K. Kubo, K. Yonezawa, Y. Ono and K. Mikoda, Design of safe hydrogen refueling stations against gas-leakage, explosion and accidental automobile collision, 16 th World Hydrogen Energy Conference, Lyon, France, June Y. Sato, E. Merilo, M. Groethe, J. Colton, S. Chiba, and H. Iwabuchi, Homogeneous hydrogen deflagrations in a sub-scale vehicle tunnel, National Hydrogen Association (NHA) Annual Hydrogen Conference 2006, Long Beach, California, March Y. Sato, H. Iwabuchi, M. Groethe, J. Colton, and S. Chiba, Experiments on hydrogen deflagration, 8 th Asian Hydrogen Energy Conference, Tsinghua University, Beijing, China, May ICMAT 2005 IUMRS-ICAM 2005, Symposium P, Materials for Rechargeable Batteries, Hydrogen Storage and Fuel Cells, Singapore, 3-8 July Selected to be published in Journal of Power Sources. R. Schefer, W. Houf, B. Bourne, and J. Colton, Turbulent hydrogen-jet flame characterization, International Journal of Hydrogen Energy, M. Groethe, J. Colton, S. Chiba, and Y. Sato, Hydrogen deflagrations at large scale, 15 th World Hydrogen Energy Conference, Yokohama, Japan, 27 June - 2 July R. Schefer, W. Houf, B. Bourne, and J. Colton, Experimental measurements to characterize the thermal and radiation properties of an open flame hydrogen plume, 15 th NHA Meeting, April 2004, Los Angeles, CA. Y. Inaba, T. Nishihara, M. Groethe, and Y. Nitta, Study on explosion characteristics of natural gas and methane in semi-open space for the HTTR hydrogen production system, Nuclear Engineering and Design 232 (2004) p M. Groethe and J. Colton, Hydrogen explosion safety studies, Poster presented at Towards a Greener World, Hydrogen and Fuel Cell Conference, Vancouver, B.C., Canada, 8-11 June M. Groethe, J. Colton, and S. Chiba, Hydrogen deflagration safety studies in a semi-open space, 14 th World Hydrogen Energy Conference, Montreal, Québec, 9-13 June M. Groethe, J. Colton, and S. Chiba, Hydrogen deflagration safety studies in a confined tube, 14 th World Hydrogen Energy Conference, Montreal, Québec, 9-13 June M. Groethe, B. Peterson, and J. Colton, Experimental facilities for hydrogen safety studies, 11 th Canadian Hydrogen Conference, Victoria, B.C., Canada, June