Large-Scale Hydrogen Deflagration and Detonations

1. 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
Poulter Laboratory
MG 8/1/05

2. 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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3.

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.
Poulter Laboratory
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4.

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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5.

Obstacle Test
• Standard and infrared video frames
~67 ms
~67 ms
~100 ms
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6.

Obstacle Test
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7.

Deflagration Data
Overpressure
Scaled Overpressure
Heat Flux
Scaled Impulse
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8.

Stoichiometric Detonation
• High-Speed Video Frames
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9.

Detonation Data
• Detonation data consistent with previous smaller scale tests
Overpressure
Heat flux
Scaled Overpressure
Scaled Impulse
Poulter Laboratory
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10.

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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11.

Tunnel with Vehicle Models
Obstacles representing
scaled vehicles.
Blockage ratio: 0.03
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12.

Pressure and Impulse
Overpressure
• Overpressure and impulse
unchanged by presence of
vehicle models.
Overpressure
Impulse
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13.

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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14.

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.
Poulter Laboratory
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15.

Partial Confinement Test
• Confinement between plates does not enhance deflagration
Standard Video Frame
~33 ms
Scaled Overpressure
IR Video Frame
~33 ms
Scaled Impulse
Poulter Laboratory
MG 8/1/05

16.

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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17.

Protective Wall Test Setup
Blast
sensors
10 m
Wall
4m
5.3 m3
Source
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18.

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
Poulter Laboratory
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19.

Large-Release Test
Rapid release of a large quantity of hydrogen that is ignited.
Sample station
Estimated
Flame Jet
18-m tower
• 300 Nm3 H2 (27 kg) released in
about 30 seconds.
• Spontaneous ignition occurred at
~360 milliseconds.
Tower
Sample station
Sample station
Igniters (15mJ)
Nozzle
Nozzle
Release
valve
Table with
drywall
insert
Pressure and heat flux
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20.

Large-Release Test
• High-Speed Video Frames
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21.

Large-Release Test
Overpressure
Heat Flux
Flame Speed
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22.

Large-Release Test
Release to Free Field
Static
Hydrogen Amount
about 5 m NTP
11 m NTP
Hydrogen
Concentration
heterogeneous
homogeneous
(30 vol , 37 m3)
Status at Ignition
Turbulent
Static
Flame Propagation
Velocity
about 100 m/sec
44 m/sec
Pressure Measurement
Range from Ignition
Peak
Overpressure
(kPa)
Impulse
(Pa-s)
Peak
Overpressure
(kPa)
Impulse
(Pa-s)
(5.3m) 5.6
(5.3m) 40
(5.9m) 4.4
(5.9m) 122
11 m
3.8
25
2.9
82
21 m
2.3
13
1.7
44
Poulter Laboratory
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23.

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.
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