LargeScale Hydrogen Deflagration and Detonations

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Large-Scale Hydrogen Deflagration and Detonations
M. Groethe E. Merilo J. Colton S. Chiba Y.
Sato H. Iwabuchi
International Conference on Hydrogen Safety 8-10
September 2005 Pisa, Italy
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Outline

• Objectives
• 300 m3 Open-Space Tests
• 1/5 Scale Tunnel Tests
• Partial Confinement Test
• Protective Blast Wall Test
• Large-Scale release (300 Nm3 H2)
• Summary

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Objective

• Acquire basic data on hydrogen deflagrations and
  detonations.
• Acquire hydrogen deflagration/detonation data for
  validation of computer simulations.

Studies were performed for IAE and administered
through NEDO as part of the Development for Safe
Production and Utilization and Infrastructure of
Hydrogen program.
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300 m3 Open-Space Tests
Obstacle-induced enhancement, scaling, free-field
blast data.

• Deflagration tests with obstacles.
• Deflagration tests without obstacles.
• Detonation tests without obstacles.

• Obstacle Test
• 0.46 m-diam
• X 3 m-tall

300 m3
5.7 m
Volume Blockage ratio 11
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Obstacle Test

• Standard and infrared video frames

67 ms
67 ms
100 ms
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Obstacle Test
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Deflagration Data
Overpressure
Heat Flux
Scaled Overpressure
Scaled Impulse
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Stoichiometric Detonation

• High-Speed Video Frames

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Detonation Data

• Detonation data consistent with previous smaller
  scale tests

Heat flux
Overpressure
Scaled Overpressure
Scaled Impulse
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Tunnel Experiments
Deflagration, H2 release, Obstacle-induced
enhancement.

• Homogeneous deflagration tests.
• Tests with and without scaled vehicles as
  obstacles.
• Scaled release and ventilation rates.

1/5 scale
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Tunnel with Vehicle Models
Obstacles representing scaled vehicles. Blockage
ratio 0.03
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Pressure and Impulse
Overpressure

• Overpressure and impulse unchanged by presence of
  vehicle models.

Impulse
Overpressure
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H2 Release Tests

• Ventilation significantly reduces H2
  concentration

• Test 14 and Test 15 0.1 kg H2 in 20 sec, no
  ventilation.
• Test 16 0.1 kg H2 in 20 sec, 1.6 m3/sec
  ventilation rate.
• Test 17 2.2 kg H2 in in 420 sec, 1.6 m3/sec
  ventilation rate.

H2 concentration
H2 concentration
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Partial Confinement Test
Deflagration enhancement from partial
confinement.

• Narrow gap between two plates provides partial
  confinement
• Flame position measured by ionization pins.
• Overpressure measured inside and outside the
  source.

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Partial Confinement Test

• Confinement between plates does not enhance
  deflagration

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Protective Wall Tests
Assess overpressure reduction by using a
protective blast wall.

• 4 m-tall by 10 m-wide wall, 4 m from edge of the
  5.3 m3 source
• Stoichiometric deflagration (bottom, center
  spark ignition)
• Pressure measured inside the source and in the
  free-field.

Test Layout
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Protective Wall Test Setup
Blast sensors
10 m
4 m
Wall
5.3 m3 Source
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Scaled Overpressure and Impulse

• Deflagration data suggests a reduction in
  overpressure and impulse.
• Previous tests with a 2 m-tall wall show
  reductions up to 30.

Scaled Overpressure
Scaled Impulse
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Large-Release Test
Rapid release of a large quantity of hydrogen
that is ignited.

• 300 Nm3 H2 (27 kg) released in about 30 seconds.
• Spontaneous ignition occurred at 360
  milliseconds.

Sample station
18-m tower
Estimated Flame Jet
Tower
Sample station
Sample station
Table with drywall insert
Nozzle
Igniters (15mJ)
Nozzle
Release valve
Pressure and heat flux
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Large-Release Test

• High-Speed Video Frames

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Large-Release Test
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Large-Release Test
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Summary

• Large-scale 300 m3 open space deflagrations and
  detonations.
• - Large obstacles do not enhance the
  deflagration.
• - Detonation data consistent with smaller scale
  tests and analytic expressions.
• Partial confinement of mixture between two
  plates.
• - Deflagration was not enhanced for this
  geometry.
• 1/5 scale tunnel tests.
• - Homogeneous deflagrations show near constant
  overpressure and impulse
• - 30 H2 blast is much higher than the
  free-field case.
• - Vehicle models do not enhance deflagration
  (BR 0.03, which is small)
• - Ventilation of the tunnel significantly
  reduces the H2 concentration.
• 4 m-tall protective blast wall.
• - Blast reduction is suggested to over twice the
  wall height.
• - Previous tests and calculations show a
  reduction that diminishes with range1.
• Large-scale release of hydrogen.
• - Release spontaneously ignite producing a blast
  followed by a flame jet.
• - Ignited release produced a higher blast
  pressure and lower impulse than a
• static homogeneous deflagration.

1 M. Groethe, J. Colton, S. Chiba, and Y. Sato,
Hydrogen Deflagrations at Large Scale, 15th
World Hydrogen Energy Conference, Yokohama,
Japan, 27 June - 2 July, 2004.