hydrogen energy

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HYDROGEN SUBSONIC UPWARD RELEASE and DISPERSION
EXPERIMENTS in CLOSED CYLINDRICAL VESSEL
Denisenko V.P.1, Kirillov I.A.1, Korobtsev S.V.1,
Nikolaev I.I.1, Kuznetsov A.V.2, Feldstein
V.A.3, Ustinov V.V.3 1 RRCKurchatov
Institute Kurchatov Sq., Moscow, 123182,
Russia 2 NASTHOL
4, Shenogin str., Moscow, 123007, Russia 3
TsNIIMash 4,
Pionerskaya, Korolev, 141070, Russia
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ABSTRACT
Report presents the preliminary experimental
results on hydrogen subsonic leakage in a closed
vessel under the well-controlled boundary/initial
conditions. Formation of hydrogen-air gas
mixture cloud was studied for a transient (10
min), upward hydrogen leakage, which was followed
by subsequent evolution (15 min) of explosive
cloud. Low-intensity (0,4610-3 m3/sec) hydrogen
release was performed via circular (diameter
0.014 m) orifice located in the bottom part of a
horizontal cylindrical vessel (about 4 m3). A
spatially distributed net of the 24 hydrogen
sensors and 24 temperature sensors was used to
permanently track the time dependence of the
hydrogen concentration and temperature fields in
vessel. Analysis of the simultaneous
experimental records for the different spatial
points permits to delineate the basic flow
patterns and stages of hydrogen subsonic release
in closed vessel in contrast to hydrogen jet
release in open environment. The quantitative
data were obtained for the averaged speeds of
explosive cloud envelop (50 fraction of the
Lower Flammability Limit) propagation in the
vertical and horizontal directions. The obtained
data will be used as an experimental basis for
development of the guidelines for an indoors
allocation of the hydrogen sensors. Data can be
also used as a new benchmark case for the
reactive Computational Fluid Dynamics codes
validation.
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PROJECT GOAL

• The general goal of our study is to create an
  experimental database to be used in ongoing
  development of the rational (non-empiric)
  guidelines for a minimal number and spatial
  allocation of the indoors hydrogen sensors

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EXPERIMENTAL SYSTEM (VESSEL and SENSORS NET)
External (left) and internal (right) views of the
experimental chamber
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LOCATION of the EXPERIMENTAL VESSEL in the
PROTECTIVE DOME
Schematic draw of protective concrete dome (R
6 m, h 6 m, H 12 m)
Air temperature inside the dome 23ºC Relative
humidity 64
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SPATIAL ALLOCATION of the GAUGES (HYDROGEN
SENSORS THERMOCOUPLE) in the EXPERIMENTAL
VESSEL
The adjusting device for gauges allocation (to
measure hydrogen concentration and temperature)
consists of seven vertical metal rods with 0,006
m diameter, which allows to fix gauge position in
rectangular coordinates Y along the
horizontal chamber axis, X in the meridional
cross-section of vessel
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SENSORS USED in the EXPERIMENTS
Thermal Conductivity Gauge TCG-3880 for gas
measurement (with open cap) by Xensor Integration
(Netherlands)
Acoustic sensors with electronic scheme of data
process and transmission by RRC Kurchatov
Institute
The accuracy of absolute concentration
measurement is varying from 2 to 5. The
relative measurement accuracy (resolution) of
concentration measurements by calibrated sensors
at stationary regimes (the absence of convective
gas flows) was 0,03 vol.
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EXPERIMENTAL SYSTEM (GAS CONTROL SYSTEM)
The main part of gas mixture conditioning and
transport system is the gas mixture preparation
device (GMPD), which allows to mix complex gas
mixtures (up to 8 components) at the
concentration range for every component from 0 to
100 with the step of 1/256 and relative accuracy
0,5, and to establish and control steady gas
flow rate from 510-6 to 710-4 m3/s (from 20 to
2560 l/h).
The gas mixture from the gas mixture preparing
device is supplied into experimental chamber
through pipe and is released into its internal
space trough a letting device. The letting device
determines the regime of gas release (diffusion
or jet-mixing) and gas velocity at fixed gas flow
rate.
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EXPERIMENTS
Formation of hydrogen-air gas mixture cloud was
studied for a transient (10 min), upward hydrogen
leakage, which was followed by subsequent
evolution (15 min) of explosive cloud.
Low-intensity ( m3/sec) hydrogen release was
performed via circular (diameter 0.014 m) orifice
located in the bottom part of a horizontal
cylindrical vessel (4 m3).
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RESULTS of the EXPERIMENTS
Time histories for the hydrogen concentrations (
vol.) for the 24 gauges (time duration 0 - 25
min)
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RESULTS of the EXPERIMENTS
HYDROGEN CLOUD EXPANSION and PROPAGATION
10,05 min
1 min
15 min
5 min
25 min
10 min
hydrogen concentration in vol.
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RESULTS of the EXPERIMENTS
The basic flow patterns and stages of hydrogen
subsonic release in closed vessel
Analysis of the time histories of hydrogen
concentration at different spatial points permits
to delineate the following basic stages in
formation and evolution of hydrogen-air mixture
cloud Step 1 upward propagation of emerging
jet, Step 2 impinging of jet with ceiling and
outward expansion of cloud, Step 3 downward
expansion of cloud from ceiling to floor. The
numerical data, received in the current and
future test runs, can be used as a basis for
empirical correlation, which defines a time
dependence of volume of flammable cloud.
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RESULTS of the EXPERIMENTS
Averaged speed of critical concentration (2
vol.) front propagation
For UNVENT 1 run, the numerical values of
reactive cloud propagation in upward vertical
direction is 0,33 m/sec, in horizontal direction
(outward) - 0,055 m/sec.
Definition of the averaged speed of critical
concentration front movement (between sensor 4
and sensor 21 time duration 0 - 0,5 min)
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RESULTS of the EXPERIMENTS ( REPRODUCIBILITY )
Reproducibility of the time histories for the
three different test runs (sensor 10). For the
points, where strong jet-sensors interaction was
absent, the experimental data were coincident
with the accuracy 0,2 vol.
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RESULTS of the EXPERIMENTS
Coincident changes of hydrogen concentrations at
points of sensors 18 and 24
The proof of symmetrical character of hydrogen
flow in the experimental vessel
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CONCLUSIONS

• The experimental set-up for investigating the
  processes of hydrogen release and mixing at
  atmospheric pressure in a medium-scale (4 m3),
  closed horizontal cylindrical vessel was prepared
  and adjusted.
• The first accurate measurements (3 test runs) of
  the time evolution of explosive hydrogen cloud
  after hydrogen injection under the
  well-controlled boundary/initial conditions have
  been carried out with the help of 24 hydrogen
  sensors and 24 temperature sensors.
• Analysis of the simultaneous experimental records
  for the different spatial points permits to
  delineate the basic flow patterns and stages of
  hydrogen subsonic release in closed vessel in
  contrast to hydrogen jet release in open
  environment. The quantitative data were obtained
  for the averaged speeds of explosive cloud
  envelop (50 fraction of the Lower Flammability
  Limit (LFL) 2 vol.) propagation in the
  vertical and horizontal directions.

ACKNOWLEDGMENTS This work was supported by the
grant (Codes and Systems for Hydrogen Safety)
from the Russian Ministry of Science and
Education and by the EU HYPER project (contract
no. 039028).
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