WP5 – Combustion - HySAFE · Temperature (K) Entropy (kJ/kg*K) Temperature – entropy (T -S) – diagram of state of real nitrogen (NIST) At initial pressure above 100 bar two

1LH2 Safety Workshop, March 6, 2019, Bergen (Norway)

Pre-normative REsearch for Safe use of Liquid HYdrogen

WP5 – CombustionMarch 8, 2019, Bergen, Norway


Work package 5: CombustionWork package number 5 Start Date or Starting Event Month 10 Work package title Combustion Participant number 1 2 3 4 5 6 7 Short name of participant KIT AL HSL HySafe NCSRD Pro-

Science UU

Person/months per participant:

6 4 4 4 12 4

2018 2019 2020

J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S OPreslhy 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34WP 5 DE5.1 DE5.2 DE5.3 DE5.5 D

E5.1 Cryogenic hydrogen jet fire experiments with detailed temperature and heat flux measurements (PS, KIT)E5.2 Flame propagation regimes at cryogenic temperatures (PS, KIT)E5.3 Flame propagation over a spill of LH2 (PS, KIT)E5.4 BLEVE (KIT)E5.5 LH2 Combustion with congestion/confinement variation (HSL)

Work package number

5

Start Date or Starting Event

Month 10

Work package title

Combustion

Participant number

1

2

3

4

5

6

7

Short name of participant

KIT

AL

HSL

HySafe

NCSRD

Pro-Science

UU

Person/months per participant:

6

4

4

4

12

4

Sheet1

201820192020

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WP 3

WP 3

E3.1Discha-AnlageD

E3.4D

WP 4

E4.2D

E4.4D

WP 5

E5.1D

E5.2D

E5.3

Arbeitspakete

201820192020


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WP 3

WP 3

E3.1Discha-AnlageD

E3.4D

WP 4

E4.2D

E4.4D

WP 5

E5.1D

E5.2D

E5.3

Experiment Serie E3.1

Hauptziel ist es, die transiente zweiphasige Entladung von kryogenen Wasserstoff-Jets zu untersuchen, um technische Korrelationen zu entwickeln und experimentelle Daten für das Modell zur Verfügung zu stellen Es werden auch Dispersionsmessungen durchgeführt, um die kryogene Düsenstruktur und die Gefahrenabstände zu untersuchen.

Die Tests werden in der DISCHA-Anlage (KIT HYKA V220, Prüfzelle Q160 oder Behälter H110) (geschlossener Raum) unter Verwendung eines Tieftemperaturbehälters von 2,867 dm³ durchgeführt; mit einer Kapazität von bis zu 200 gLH2.

Die Freisetzungsmessungen beinhalten eine zeitliche Änderung des Drucks und der Temperatur innerhalb des Tanks, entlang des Freisetzungsrohrs und an der Austrittsdüse, eine Variation des Tankgewichts und des Schubs. Massendurchsatz, Austrittsgeschwindigkeit und Austrittsdampfqualität werden aus den Rohdaten abgeleitet. Dispersionsmessungen umfassen BOS

Bilder der Strahl- und Konzentrationsprofile (Wasserstoff, Sauerstoff und Feuchtigkeit) mittels Probenahme

Umgebungsbedingungen (Temperatur, Druck, Feuchtigkeit) werden überwacht.

Der Bereich der zu untersuchenden Parameter ist: 4 Lagerdrücke im Bereich (1-200 bar), 4 Lagertemperaturen im Bereich (25-200K), 4 Freigabedurchmessergrößen (0,5-4 mm), 3 Tankentnahmepunkte ( oben / gasförmig, unten / flüssig, dazwischen).

Komponenten:

Tieftemperaturbehälter 2,867 dm3 = Kapazität bis zu 200 gLH2

Sheet3

201820192020


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WP 3

WP 3

E3.1Discha-AnlageD

E3.4D

WP 4

E4.2D

E4.4D

WP 5

E5.1D

E5.2D

E5.3

MilestonesDeliverables (brief description and month of delivery)

MS5.1 Experiment series E5.1 (KIT Jet fire) started, month 8 D5.1 Theory and Analysis of Combustion of Pre-mixed systems with cryogenic hydrogen (public report, month 18), Leader KIT, partners all.

MS5.2 Experiment series E5.1 completed, month 12D5.2 Computational investigation of combustion phenomena with cryogenic hydrogen (public report, month 36), Leader KIT, partners all.

MS5.3 Experiment series E5.2 (KIT FA DDT) started, month 5 D5.3 Experimental investigation of pre-mixed combustion phenomena with cryogenic hydrogen (public report, month 36), Leader KIT, partners all.

MS5.4 Experiment series E5.2 completed, month 11D5.4 Summary of experiment series E5.1 results (confidential report, month 15), PS

MS5.5 Experiment series E5.3 (KIT Flame dynamics above Pool) started, month 18 D5.5 Summary of experiment series E5.2 results (confidential report, month 14), PS

MS5.6 Experiment series E5.3 completed, month 21 D5.6 Summary of experiment series E5.3 results (confidential report, month 25), PS

MS5.7 Experiment series E5.5 (HSL Flame in cold obstructed cloud) started, month 25 D5.7 Summary of experiment series E5.5 results (confidential report, month 34), HSL

MS5.8 Experiment series E5.5 completed, month 31

201820192020

JFMAMJJASONDJFMAMJJASONDJFMAMJJASOND

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WP 5DD

E5.1D

E5.2D

E5.3D

E5.5D

201820192020

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WP 3

WP 3

E3.1Discha-AnlageD

E3.4D

WP 4

E4.2DDD

E4.4D

WP 5

E5.1D

E5.2D

E5.3

E5.5

Arbeitspakete

201820192020


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WP 3

WP 3

E3.1Discha-AnlageD

E3.4D

WP 4

E4.2D

E4.4D

WP 5

E5.1D

E5.2D

E5.3

Experiment Serie E3.1

Hauptziel ist es, die transiente zweiphasige Entladung von kryogenen Wasserstoff-Jets zu untersuchen, um technische Korrelationen zu entwickeln und experimentelle Daten für das Modell zur Verfügung zu stellen Es werden auch Dispersionsmessungen durchgeführt, um die kryogene Düsenstruktur und die Gefahrenabstände zu untersuchen.

Die Tests werden in der DISCHA-Anlage (KIT HYKA V220, Prüfzelle Q160 oder Behälter H110) (geschlossener Raum) unter Verwendung eines Tieftemperaturbehälters von 2,867 dm³ durchgeführt; mit einer Kapazität von bis zu 200 gLH2.

Die Freisetzungsmessungen beinhalten eine zeitliche Änderung des Drucks und der Temperatur innerhalb des Tanks, entlang des Freisetzungsrohrs und an der Austrittsdüse, eine Variation des Tankgewichts und des Schubs. Massendurchsatz, Austrittsgeschwindigkeit und Austrittsdampfqualität werden aus den Rohdaten abgeleitet. Dispersionsmessungen umfassen BOS

Bilder der Strahl- und Konzentrationsprofile (Wasserstoff, Sauerstoff und Feuchtigkeit) mittels Probenahme

Umgebungsbedingungen (Temperatur, Druck, Feuchtigkeit) werden überwacht.

Der Bereich der zu untersuchenden Parameter ist: 4 Lagerdrücke im Bereich (1-200 bar), 4 Lagertemperaturen im Bereich (25-200K), 4 Freigabedurchmessergrößen (0,5-4 mm), 3 Tankentnahmepunkte ( oben / gasförmig, unten / flüssig, dazwischen).

Komponenten:

Tieftemperaturbehälter 2,867 dm3 = Kapazität bis zu 200 gLH2

20182019

JFMAMJJASONDJFMAMJJASONDJF

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WP 3

WP 3

E3.1Discha-AnlageD

E3.4D

WP 4

E4.2

E4.4D

WP 5

E5.1D

E5.2D

E5.3


Simulations Simulations to be done The development of numerical models based on the theory and

recent experimental results Pre-test (blind) simulations of all phenomena for cryogenic LH2

combustion Validation against new combustion experiments and code

improvement Competitive comparison or numerical results between partners’

simulations Simulations of real accident scenarios relevant to LH2 combustion Generation of simplified engineering correlations for safety

analysis


ExperimentsKIT, PS: Cryogenic hydrogen jet fire experiments with detailed temperature

and heat flux measurements (E5.1) Flame propagation regimes at cryogenic temperatures (E5.2) Flame propagation over a spill of LH2 (E5.3) BLEVE (E5.4) –an analysis of existing or shared data (SH2IFT)HSL: LH2 Combustion with congestion/confinement variation (E5.5)


Cryogenic hydrogen jet fire experiments (E5.1) Objectives To close knowledge gaps and to generate the data for model validation on

hazard distances due to pressure and heat radiation effects under delayed ignition of cryogenic hydrogen jet.

Measurements Pressure inside the tank (1 sensor) Temperature inside the tank (3 thermocouples) Distant pressure (3-5 sensors) Heat flux (2-3 sensors) Axial temperature along ignited jet (5-10 sensors) A high speed video combined with BOS technique (2-3 cameras)

Variables 2 initial temperatures (300K, 80K) 3 bulk pressures within the range 5-200 bar 3 nozzle diameters (1, 2, 4 mm) 5 ignition locations (0-2 m) 4 time delays (0-1 s)


Experimental layout 1

15/03/2019 - Hyindoor - WP1 – T1.1 – Project title

(B)

(T1) (T2)

(T3)

(D)


Dr. Mike Kuznetsov, IKET

Experimental data analysis

2 3 4 5 6 7

100

150

200

250

300

Saturation 1 bar 5 bar 10 bar 20 bar 30 bar 50 bar 75 bar 100 bar 150 bar 200 bar

NIST Nitrogen Equation of State

Tem

pera

ture

(K)

Entropy (kJ/kg*K)

Temperature – entropy (T-S) – diagram of state of real nitrogen (NIST)

At initial pressure above 100 bar two-phase flow may occur



For 4-mm nozzle the entropy deviation appears when temperature difference reaches 120 – 150K due to heat transfer gas – solid wallNon- adiabatic blow down process occurs approaching subcritical blow down regime This was the reason why we did not reach the two-phase blow down process

Experimental data analysisReal nitrogen release at different initial pressures (4-mm nozzle)

2 3 4 5 6 7

100

150

200

250

300 Saturation 1 bar 5 bar 5 bar(4 mm Exp) 10 bar 20 bar 30 bar 50 bar 50 bar(4 mm Exp) 75 bar 100 bar 100 bar(4 mm Exp) 150 bar 200 bar 200 bar(4 mm Exp)

Tem

pera

ture

(K)

Entropy (kJ/kg*K)



Experimental data analysisReal nitrogen release at 200 bar and different nozzle diameter

2 3 4 5 6 7

100

150

200

250

300

0.5 mm nozzle

1 mm nozzle

2 mm nozzle

Saturation 1 bar 5 bar 10 bar 20 bar 30 bar 50 bar 75 bar 100 bar 150 bar 200 bar 200 bar(0.5 mm Exp) 200 bar(1 mm Exp) 200 bar(2 mm Exp) 200 bar(4 mm Exp)

Tem

pera

ture

(K)

Entropy (kJ/kg*K)

4 mm nozzle

The less nozzle diameter and the longer the blow down process, the lower the temperature when non adiabatic effect or entropy deviation appears (at 200 bar):0.5-mm nozzle ∆T = 40K ; 1-mm nozzle ∆T = 60K ; 2-mm nozzle ∆T = 120K ; 4-mm nozzle ∆T = 170K ;



Scaling of transient discharge pressures

Scaling by dimensionless p+ and t+ results in very good agreement of the tests with different initial pressures for the nozzle diameter more than 2 mm.There is some difference appears for smallest nozzle diameters due to the above discussed heat transfer effects and the discharge time. The slowest experiments (0.5 and 1 mm nozzles) show the highest values for p+(t+).

( )( )

12

121

21

211

−−

+−+−

+

⋅

+

−+=

γγ

γγ

γγ tpp+ = p(t)/p0 - dimensionless pressure;

t+ = t/tchar - characteristic release time;

tchar = V/(A·c0) - characteristic release timeN2(293K, 200 bar)

0

50

100

150

200

250

0 20 40 60 80 100 120 140 160 180 200time [s]

pres

sure

[bar

]

d=0.5 mmd=1 mmd=2 mmd=3 mmd=4 mm

N2(293K, 200 bar)

0

0.2

0.4

0.6

0.8

1

0 2 4 6 8 10 12 14 16 18 20t+

p+

d=0.5 mmd=1 mmd=2 mmd=3 mmd=4 mm


T-S diagram of state of hydrogen

15/03/2019 - Hyindoor - WP1 – T1.1 – Project title

T P Density Sound Speed H2 inventory Characteristic release time (s)

(K) (bar) (kg/m³) (m/s) (g) Nozzle diameter (mm)0.5 1 2 4

300 200 14.4 1493 41.3 9.78 2.45 0.61 0.15300 150 11.1 1448 31.9 10.1 2.52 0.63 0.16300 100 7.6 1404 21.9 10.4 2.60 0.65 0.16300 50 3.9 1361 11.3 10.7 2.68 0.67 0.17300 20 1.6 1335 4.6 10.9 2.73 0.68 0.17

0.5 1 2 480 200 48.2 1207 138.3 12.1 3.03 0.76 0.1980 150 40.5 1065 116.1 13.7 3.43 0.86 0.2180 100 29.9 917 85.6 15.9 3.98 1.00 0.2580 50 15.7 792 45.0 18.4 4.61 1.15 0.2980 20 6.2 747 17.8 19.5 4.89 1.22 0.31


Cryogenic jet fire experiments (E5.1) For the ignited experiments an ignition device will be added to the

existing facility

Selected experiments of the unignited series will be repeated with ignition

Parameters to be varied include:• Mass flow rate

(bulk pressure)• Nozzle diameter• Ignition position• Ignition delay time.

LH2

Flow-Meter

Valve

Nozzle

P

T

T

PosI

PosII

Line as shortas possible

13 22.06.ISFV14 - 14th International Symposium on Flow Visualization

June 21-24, 2010, EXCO Daegu, KoreaDr. Mike Kuznetsov, IKET

FlameJet flow

Flame propagation regimes in hydrogen jet

H2-jet (5 bar, 290K), Ønozzle = 4 mm,tinj=3s (3.5 g/s),framing time step = 300ms

xign = 800 mm xign = 900 mm

0

0.1

0.2

0.3

0.4

0 200 400 600 800 1000 1200 1400

(x/d0)·(ρa/ρH2)1/2

1/Vo

l% H

21 mm, T=298K2 mm, T=298K1 mm, T=80K2 mm, T=80K

4%

11%

30%fast

slow

no ignition

14 22.06.ISFV14 - 14th International Symposium on Flow Visualization

June 21-24, 2010, EXCO Daegu, KoreaDr. Mike Kuznetsov, IKET

Flame propagation regimes in hydrogen jet

11%H2

0.1

1

10

100

1000

10000

0.1 1 10 100 1000 10000lT/δ L

u'/S

L

Ka=1Da=1

Re=1

Re=100

Re=10000

Flamelet Regime

Well-stirred Reactor

Distributed Reaction ZoneQuenching

DNS

Phase diagram of turbulent flame propagation regimes

• Laminar flamelet regimes (Ka1)Typical for highly reactive laminar or quasi-laminar flames (t < tK). Thin flames zone. Maximum what turbulence can achieve is to wrinkle the flame

• Distributed reaction zone (Ka>1, Da >1)Typical for thick flames. Small eddies already can penetrate into the flame brush to make it thicker (tT > t > tK). Wrinkled or corrugates flames. Above the quenching line local quenching can occur.

• Well stirred reactor zone (Ka>1, Da = 5 cm (conservative) lT /δT~ 200Dimensionless turbulent pulsations : u’/SL = 70

Critical point characteristics (CH2 = 11%):


SCALING OF THERMAL MEASUREMENTS

T0 [K] d0

p0 [bar] m [g/s] xQmax [m] Lvis [m] 2 20 3,3

290 4 4 3,3

0,75 1,25

14 3,3 1 1,66 2

20 4,4 1,1 1,83 3 3,3 1 1,66

80 4

4 4,4 1,25 2,08

• Nice scaling of thermal properties even including the initial temperature effect. Behavior is similar to previous experimental data (Sandia Nat. Lab.)

• Maximum heat flux is the most important characteristic of burned hydrogen jet for conservative hazard evaluation qmax

0.0

0.20

0.40

0.60

0.80

1.0

1.2

0.0 0.50 1.0 1.5 2.0 2.5 3.0

C*_v s_x/Lvis_all.qpa2

C2H4 11.2C2H4 20.2CH4 12.5CH4 6.4C2H2 18.1C2H2 56.5Fit to dataPresent H2 data:d=1.905 mmd=7.938 mm (5 sec)(10sec)(20sec)(5sec)(10sec)(20sec)

C*

x/Lvis

Fuel S (kW)

Data From Large-Scale H 2 TestsListed Belo w:

T0 [K]

d0 [mm]

p0 [bar]

m [g/s]

xQmax [m]

Lvis [m]

290

2

20

3,3

0,75

1,25

4

4

3,3

80

2

14

3,3

1

1,66

20

4,4

1,1

1,83

4

3

3,3

1

1,66

4

4,4

1,25

2,08


SCALING OF THERMAL MEASUREMENTS

• All experimental data on maximum heat fluxfor different distances from jet axis rnormalized by visible flame length Lf arecollapsed in one curve

• For the same mixture and for high momentum jets the visible flame length Lf israther simple function of nozzle diameter andhydrogen density in a pressurized volume:

qmax = 0.74(r/Lf)-1.59

0

1

2

3

4

5

6

7

8

0 0.2 0.4 0.6 0.8 1 1.2

r/Lf

qmax

[kW

/m2 ]

20bar, 290K, d=2mm4 bar, 290K, d=4mm14 bar, 80K, d=2mm20 bar, 80K, d=2mm3 bar, 80K, d=4mm4 bar, 80K, d=4mm

)5(23 >⋅=∞

Frfd

L es

f ρρ

1.0

10

100

0.1 1.0 10.0 100.0

H2 choked (d=7.94 mm)H2 unchoked (d=7.94 mm)H2 choked (d=5.08 mm)H2 (d=1.91 mm)CH4 (d=1.91 mm))CH4 (Kalghatghi)C3H8 (Kalghatghi)H2 (Kalghatghi)Buoyant regime (d=1.91 mm)

L*

Froude number (Fr)

L*=23L*=13.5Fr 2/5/(1+0.07Fr )2 1/5• Using scale correlation for maximumheat flux:

qmax = 0.74(r/Lf)-1.59

we can evaluate the safety distance forgiven level of critical heat fluxcorresponding, for instance, to pain limitor different burn degree for human skin


C

radrad

Hm

SX∆⋅

= ⋅

Xrad: Radiant fractionSrad: Total thermal energym Mass flow rate∆Hc: Enthalpy of reaction

T0 [K] d0

p0

m

Lvis [cm] Xrad 2 20 3,3 125 0,032 290 4 4 3,3 125 0,032

14 3,3 166 0,056 2 20 4,4 183 0,051 3 3,3 166 0,056

80 4

4 4,4 208 0,066

HEAT RADIATION OF HYDROGEN JET

C

visvis

vis

C

Zylinder

C

radrad

Hm

LLLQ

Hm

OQ

Hm

SX∆⋅

+⋅

=∆⋅

⋅=

∆⋅= ⋅

⋅

⋅

⋅

⋅

222max

maxπ

• Typical values of radiant fraction are:Xrad = 0.03 for 290KXrad = 0.06 for 80K

• Radiant fraction depends on jet scalebut residence time as a measure ofscale is not convenient for practicalpurposes:

• Visible flame length can be used forscaling

)3()(

20

2

JJ

sfvisff ud

fLWT

ρρ

=

T0 [K]

d0 [mm]

p0 [bar]

m [g/s]

Lvis [cm]

Xrad

290

2

20

3,3

125

0,032

4

4

3,3

125

0,032

80

2

14

3,3

166

0,056

20

4,4

183

0,051

4

3

3,3

166

0,056

4

4,4

208

0,066


Thermal hazards CFD modellingUU WiP on KIT cryogenic hydrogen jet fire tests

The CFD approach previously validated against SNL cryogenic ignited releases is employed to model the horizontal jet fire tests performed in KIT with release conditions: P=3-20 bar T=80 K d=2 mm and 4 mm

Preliminary tests on the effect of: Humidity Ventilation system parameters

Aim of the study: Prediction of radiative heat flux aside the jet fire Prediction of flame length and calculation of associated hazard distances

for horizontal releases

Preliminary results on OH mole fraction distribution – top view

Radiometers


Cryogenic hydrogen jet fires (UU)

The employed CFD model has been previously validated against experiments by SNL on cryogenic hydrogen fires from storage with pressure up to 5 bar abs and temperature in the range 48-82 K.

Operating conditions at the releaseTest No. T, K P, bar abs d, mm ṁ, g/s

1 64 2 1.25 0.332 48 2 1.25 0.383 78 4 1.25 0.56

Thermal dose distribution for Test 3

Thermal dose harm levels: time versus radial distance with max TD for Test 3

Thermal dose calculation

Burn Severity Threshold Dose for infrared radiation, (kW/m2)4/3sFirst degree 80-130

Second degree 240-730Third degree 870-2640


SAFETY DISTANCES

• Maximum radiation reached at safety distance equal to Lf

• Visible flame length Lf increases with nozzle diameter and pressure increase and decreases with initial temperature increase

• Side view area S = 0.17Lf2• Axial view area S = 0.02Lf2• As a safety distance for axial

position visible flame length can be used Lf

Visible flame length

0

10

20

30

40

50

60

70

80

90

100

0 5 10 15 20 25 30d [mm]

L f [m

]

33K, 10 bar

33K, 30 bar

80K, 10 bar

80K, 30 bar

290K, 10 bar

290K, 30 bar

qmax (Lf)


SAFETY DISTANCES

• Safety distances calculated for pain limit at exposure (10 sec)

• Maximum radiation reached at safety distance in the point 0.6Lf

• Safety distance increases with nozzle diameter and pressure increase. It decreases with initial temperature increase

• Side view area S = 0.17Lf2• Axial view area S = 0.02Lf2• As a safety distance for axial

position visible flame length Lf can be used

Safety distances (pain limit)= first degree

0

5

10

15

20

25

0 5 10 15 20 25 30d [mm]

Ls[m

]

33K, 10 bar

33K, 30 bar

80K, 10 bar

80K, 30 bar

290K, 10 bar

290K, 30 bar

P = 10, 30 barT = 33, 80, 290Kd = 1, 3, 10, 30 mm

qmax (0.6Lf)

A AA-A


Damage diagram

Maximum exposure times for different degrees of skin damage fromthermal radiation of turbulent hydrogen gas jet flames


WP5 - Activities plan and progress (UU)

Development and validation of CFD models and engineering correlationsfor evaluation of thermal hazards from cryogenic jet fires along and asidethe jet axis:Small scale releases (P up to 6 bar and d=1.25 mm)− Larger scale releases− Hazard distances for horizontal jet fires− Higher pressure releases (P > 10 bar – KIT E5.1)

Development of UDF for evaluation of thermal dose Simulations on pressure-peaking phenomenon for ignited cryogenic

release indoors (if experiment available) Simulations on BLEVE (if experiments KIT E5.4 available)


Expected results (reference data)Flame propagation regimes

4 8 12 t, s

0.0 0.4 0.8 1.2

0.6 0.8 1.0 t, s

0 2 4 6 8

10 0.2 0.21 0

10 20 30

∆ P/Po,

t, s

B R = 0 . 6 ( a i r )

0 10 20 30 40 50 60 70 x / D

0

200

400

600

800

1000

1200

1400

V , m

/s 5 2 0 m m 9%H 2

10% 2 11% 2

8 0 m m 9%H 2 10% 2 11% 2 13% 2

1 7 4 m m 9%H 2 10% 2 11% 2 15% 2 25% 2

s l o w f l a m e s

f a s t f l a m e s

q u a s i - d e t o n a t i o n s

σ > σ *

L>7 λ

E5.2: Flame propagation regimes at cryogenic temperatures (PS, KIT)

4

8

12

t, s

0.0

0.4

0.8

1.2

0.6

0.8

1.0

t, s

0

2

4

6

8

10

0.2

0.21

0

10

20

30

P/Po,

t, s

B

R

=

0

.

6

(

a

i

r

)

0

10

20

30

40

50

60

70

x

/

D

0

200

400

600

800

1000

1200

1400

V

,V , m/s

m

/s

5

2

0

m

m

9%H

2

10%

H

2

11%

H

2

8

0

m

m

9%H

2

10%

H

2

11%

H

2

13%

H

2

1

7

4

m

m

9%H

2

10%

H

2

11%

H

2

15%

H

2

25%

H

2

s

l

o

w

f

l

a

m

e

s

f

a

s

t

f

l

a

m

e

s

q

u

a

s

i

-

d

e

t

o

n

a

t

i

o

n

s

>

*

L>7


Prediction of the resultsCritical expansion ratio for an effective flame acceleration

Lack of fundamental data on combustion properties at cryogenic temperaturesToo far extrapolation to be properly predictedCannot be theoretically predicted up to nowExperiments should be done

T, K CH2, %mol σ*

300 11 3.75200 10.34 4.92150 10.09 6.14100 9.58 8.49

78 9.13 10.67

50 8.60 13.89


Prediction of the resultsDetonation cell size (7λ criterion)

Lack of fundamental data on combustion properties at cryogenic temperaturesToo far extrapolation to be properly predictedExperiments should be done (sooted plates technique)

Hydrogen-air

0

1

2

3

4

5

6

100 200 300 400 500T, K

λ, m

m

0.9827 bar0.6953 bar0.4918 barZitoun, [1]Zitoun, [1]Zitoun, [1]Denisov[5]Denisov[5]Denisov[5]

Konnov

extrapolations


E5.2: Combustion-Tube-Facility

Experimental Setup

• Facility installed to a tent with removable sides in the free field behindmain hall of HYKA,

• Control units in a container besides the facility.

The critical conditions for flame-acceleration and DDT for Hydrogen-Air-Mixtures at cryogenic temperatures will be investigated


E5.2: Combustion-Tube-Facility• Shock-Tube

• End-Flange with ports for: • Thermocouple• Pressure-Sensor• Gas-Outlet

• Front-Flange with ports for: • Gas-Inlet• Glow-Plug• Thermocouple

• Along the tube 52 ports for:• Pressure Sensors

(2 different types),• Phototransistors


E5.2: Combustion-Tube-Facility• Instrumentation

• Ports arranged in groups of: 4 ports (close to ends) and 3 ports (main part of tube)evenly distributed along the circumference.

• Ports for Phototransistors andsmall Pressure Sensors for higher pressures (700 bar) are the same,

• Ports for larger Pressure Sensors (lower pressures, 7 bar) are significantly larger.• For fabrication reasons (deformation of tube due to welding of different adapters)

the large ports will be distributed helically in the positions along the tube.


E5.2: Combustion-Tube-Facility Current Status

• Tube and flanges currently in KIT-workshop for welding, assembly and installation of ports,

• Dimensions:L = 5000 mmDin = 54 mmDout = 73 mm.


E5.2: Combustion-Tube-Facility Current Status Fortunately work on tube has

begun, progress is visible…

Holes drilled, surface prepared for welding of sockets

Preparation of flanges

Tube on machine

Sockets prepared

Tube ends prepared for welding of flanges


E5.2: Combustion-Tube-Facility

• 54 mm id, 10-mm wall thickness and 5-m long• 2 different obstacles (BR 30% and BR 60%),• obstacles will be positioned evenly along the complete tube length

(spacing: 1 inner diameter of tube) via three thin threaded rods,• obstacles were manufactured externally (already delivered).

• Obstacles

BR 30% BR 60%


Combustion-Tube-Facility Test Parameters

• 2 temperatures in the range 70 K to 100 K,• 2 blockage ratios (30% and 60%)• 10 H2-concentrations within the ranges

• 6 to 12 Vol.% H2 (for σ* evaluation)• 15 to 20 Vol.% H2 (for λ evaluation)• 30 Vol.% H2 (for λ evaluation)• 60 to 75 Vol.% H2 (for λ evaluation)


A proper test temperature evaluation

T, K P, bar ps, bar %O2 max

ps, bar %N2 max

%H2 %air max

Note

69 1 0.0521 5.2 0.332 33.2 75.2 24.8 UFL75 1 0.1455 14.5 0.760 76.0 30.8 69.2 St77 1 0.1971 19.7 0.972 97.2 6.2 93.8 LFL

65 0.5 0.0233 4.7 0.174 34.8 77.8 22.2 UFL66 0.5 0.0288 5.8 0.206 41.2 72.6 27.4 St71 0.5 0.0749 15.0 0.445 89.1 28.7 71.3 LFL72 0.5 0.0891 17.8 0.512 100.0 15.2 84.8


Planned Procedure Planned Procedure

• Tube is evacuated and purged with gaseous nitrogen several times,• Tube is carefully filled with LN2 until a liquid phase stays inside,• Tube is kept in this state for several minutes to achieve thorough

cooling of the complete tube to approx. 80 K,• Tube is drained through a sensor port close to the end flange,• Tube is again evacuated several minutes to remove the remaining

nitrogen,• Evacuated tube is filled with test mixture generated by mass flow

controllers (bypass flow during initial phase of mixture generation),• All valves to the tube are closed,• If a higher temperature than 80 K is desired the tube is left to warm up

for some time,• Mixture is ignited by a glow-plug.


Flame propagation over a spill of LH2(E5.3) Objectives To evaluate a danger of flame propagation over a spill of LH2 in

presence of inverse vertical hydrogen concentration gradient at cryogenic.

Measurements Local hydrogen concentration (an array 5x6 units) Vertical temperature profile (3-5 thermocouples) Dynamic pressure sensors (5 sensors) Photodiodes (10 sensors) Ion probes (10 sensors) Axial temperature along the system (5-10 sensors) A high speed video combined with BOS technique (2-3 cameras)

Variables 3 hydrogen concentration gradients 3 layer thicknesses 3 blockage ratios (0, 30 and 60%)


„Pool“-Facility Experimental set-up

• It seems to be difficult to generate a pool of LH2 with a surface of 1 m² with a reasonable budget for the enormous amount of LH2 that has to be spilled.

• If the pool is generated the atmosphere around it will consist of gaseous H2 with traces of other gases

The decision could be to provide the same conditions as above the LH2 spill. We just need to provide the same hydrogen concentration and temperature profile as for predefined LH2 evaporation rate.


Equilibrium temperature of LH2-air mixture

Hydrogen %v/v

Temperature ᵒC

Temperature K

4 -0.12 273.110 -15.6 257.615 -28.5 244.720 -41.4 231.825 -54.5 218.730 -67.6 205.635 -80.9 192.340 -94.3 178.945 -107.9 165.350 -121.7 151.555 -136 137.260 -150.6 122.665 -165.9 107.370 -181.9 91.375 -197.9 75.3

So that it will be a gradient of hydrogen concentration and temperature as well. Within the flammability limits the temperature changes from 273K(LFL) to 75K(UFL).206K corresponds to stoichiometric hydrogen concentration.


Experimental procedure Installation of semiconfined box inside of the safety vessel. Injection of pre-cooled hydrogen at the bottom of combustion

chamber through a multiple nozzle dispersion system to create inverse gradient of hydrogen concentration and temperature.

A side ignition of hydrogen cloud is initiated at certain time delay corresponding to natural hydrogen concentration profile above the spill of LH2.

Measurements of flame propagation velocity and combustion pressure.


E5.5 LH2 Combustion with congestion/confinement variation (HSL)(‘realistic’ scenario)

‘Realistic’ release into open/semi-open congestion from plume/pool to be considered

This option has more variables such as concentration and temperature of gas within congestion

Congestion rig will be left open as heat will be removed immediately by surrounding air and structure in an enclosed volume

Biggest challenge will be ensuring ignition due to variability from wind effects


WP5 – Contrived experiments

The following test arrangement has been discounted as the test set up is contrived, i.e. fully enclosed and pre-cooled This test was designed to give flame speed and pressure

information at the expense of a realistic scenario INERIS experiments should provide the necessary data

already, therefore HSL will focus on more realistic scenarios


Experimental layout

Size: 2 m * 3 m * 3 m = 18 m3

Used in: Royle, M, Shirvill, LC, Roberts, T, Vapour cloud explosions from the ignition of methane/hydrogen/air mixtures in a congested region, International Conference on Hydrogen Safety. 11-18 Sept. 2007, San Sebastian, Spain. (PS/06/07)

Potentially high noise levels so careful consideration needed

This would provide a useful data comparison

Could use a smaller congestion rig if this was an issue

Also have a 1 m3 congestion rig for further obstruction


Experimental procedure

Variables:‒ LH2 pool or jet

‒ Congestion level

‒ Confinement level

‒ LH2 jet flow rate

Ignition source located just downstream of rig to limit inventory of unburnt gas prior to entry into the congestion rig, this is to limit noise

Pool in congestion rig Jet release into congestion rig

Higher flow rate release into rig, larger orifice


P&ID


WP5 - Option 1 (Realistic)

Work Packag

e

Experimental Subtask Test No. Gas Pool/jet Orifice size Blockage ratio Confinement

5 5.5 5.5.1 Hydrogen Jet ¼” 1.25% (8 rows) Open5 5.5 5.5.2 Hydrogen Jet ½” 1.25% (8 rows) Open5 5.5 5.5.3 Hydrogen Jet 1” 1.25% (8 rows) Open5 5.5 5.5.4 Hydrogen Jet ¼” 2.5% (15 rows) Open5 5.5 5.5.5 Hydrogen Jet ½” 2.5% (15 rows) Open5 5.5 5.5.6 Hydrogen Jet 1” 2.5% (15 rows) Open5 5.5 5.5.7 Hydrogen Pool 1” 1.25% (8 rows) Open5 5.5 5.5.8 Hydrogen Pool 1” 2.5% (15 rows) Open5 5.5 5.5.9 Hydrogen Jet ¼” 1.25% (8 rows) 2 sides closed5 5.5 5.5.10 Hydrogen Jet ¼” 1.25% (8 rows) 2 sides closed

Blockage ratio? (too small and too small differenceLH2? m?

.


Hydrogen %v/vTemperature

ᵒC

15 -28.5

20 -41.4

25 -54.5

30 -67.6

35 -80.9

40 -94.3

45 -107.9

50 -121.7

55 -136.0

60 -150.6

65 -165.9

70 -181.9

WP5 – LH2 conc. to temp conversion

?


WP5 - Test procedure (Realistic tests)

1. Set up congestion rig as per test schedule

2. Circulate LH2 around pipe circuit until pipework is at liquid temperature and flow is liquid only

3. Switch release to flow through required outlet nozzle

4. Maintain jet flow until hydrogen is established within congestion rig both visually and using gas concentration and temperature probes

5. Fire the igniter (gerb) when a flammable mixture of cold hydrogen and air is present


WP5 - Combustion with congestion/confinement

Instrumentation 2x blast pressure transducers at 5 m and 10 m from source, (ranged 0-2 bara, 500 kHz logging rate) 2x blast pressure transducers within congestion rig (ranged 0-5 bara, 500 kHz logging rate) Audible sound meters at 50 m and 100 m approximately Remote ignition system with multiple outputs, spark plugs and electrochemical igniters Thermocouples (16x co-located with vol% sensors and additional positions) Gas concentration measurement (vol% sensors within congestion rig, if thermocouples prove reliable in WP3 then

no vol% sensors will be used) High speed video and IR

Infrastructure Congestion rig Protective concrete block wall for tanker Protective steel shield in front of release station 1 m wide x 2 m high


WP5 - Combustion with congestion/confinement

Distance arcs of 215 m and 475 m

Assuming 135 dB limit at extremes

Equates to: 0.137 kg TNT @ 215 m 1.480 kg TNT @ 475 m


Experimental facilityHYKA A2 (V = 220 m3 )

Experimental procedureThe tests will be performed inside the HYKA-A2 vessel (220

m3). A pressurized liquid hydrogen inventory of different amount

(


Expected resultsMaximum radius of fireball

Lack of fundamental data on hydrogen fireball characteristics at cryogenic temperatures

Behaves as BLEVEExperiments should be done

D=5.33⋅M0.327 td = 0.45⋅Mf1/3. E = 8.085⋅Mf.

H2


Expected resultsCharacteristic time for fireball

Lack of fundamental data on fireball characteristics at cryogenic temperatures

Behaves as BLEVEExperiments should be done

BLEVE (Detonation, Sonic flames)


Preliminary tests in soap bubbles

10% H2/air

40% H2/O2

50% H2/O2


Scale correlations


Effect of scale. Experiments (DF)

Heat radiation of the surface (FB - DF)


Grey body radiation phenomenaEffect of scale

a)

k·R = 10

k·R = 2

k·R = 1

k·R = 0.5

k·R = 0.2

k·R = 0.1

b)-1.0 -0.5 0.0 0.5 1.0

0.0

0.2

0.4

0.6

0.8

1.0L/R-1=1

L/R-1=0.1

L/R-1=0.01

L/R-1=0.001

L/R-1=0.0001

L/R-1=0.00001

ε

r/R

ϕ

ϕ

ψ

x

R

OA

R1

fx( , )ϕ ψ

ds

dS

r

Lε(ϕ, ψ) = 1 - exp(-k⋅xf(ϕ, ψ)),

Emissivity of the surface (FB)


Effect of scale. Experiments (DF)

Hemisphere radiation over surface (FB)

( ) ϕψϕψπ

π

π

π

dedqrq xk )cos()(cos12)( 22/

2/

2/

0

⋅⋅−⋅= ∫∫−

⋅−

( ) ϕψϕψπ

ππ

dedqrqrR

xk )cos()(cos12)( 22/

)/arccos(

2/

0

⋅⋅−⋅= ∫∫ ⋅−

r < R

r > R

WP5 – Combustion�March 8, 2019, Bergen, Norway Work package 5: CombustionSimulationsExperimentsCryogenic hydrogen jet fire �experiments (E5.1)Experimental layout 1Foliennummer 7Foliennummer 8Foliennummer 9Foliennummer 10T-S diagram of state of hydrogen�Cryogenic jet fire experiments (E5.1)Flame propagation regimes in hydrogen jetFlame propagation regimes in hydrogen jetSCALING OF THERMAL MEASUREMENTSSCALING OF THERMAL MEASUREMENTSFoliennummer 17Thermal hazards CFD modellingCryogenic hydrogen jet fires (UU)SAFETY DISTANCESSAFETY DISTANCESDamage diagramWP5 - Activities plan and progress (UU)E5.2: Flame propagation regimes at cryogenic temperatures (PS, KIT)Foliennummer 25Foliennummer 26E5.2: Combustion-Tube-FacilityE5.2: Combustion-Tube-FacilityE5.2: Combustion-Tube-FacilityE5.2: Combustion-Tube-FacilityE5.2: Combustion-Tube-FacilityE5.2: Combustion-Tube-FacilityCombustion-Tube-FacilityA proper test temperature evaluation Planned ProcedureFlame propagation over a spill of LH2� (E5.3)„Pool“-FacilityEquilibrium temperature �of LH2-air mixtureExperimental procedureE5.5 LH2 Combustion with congestion/confinement variation (HSL)� (‘realistic’ scenario)WP5 – Contrived experimentsExperimental layoutExperimental procedureP&IDWP5 - Option 1 (Realistic)�WP5 – LH2 conc. to temp conversionWP5 - Test procedure (Realistic tests)WP5 - Combustion with congestion/confinementWP5 - Combustion with congestion/confinementFoliennummer 50Foliennummer 51Foliennummer 52Preliminary tests in soap bubblesScale correlationsEffect of scale. Experiments (DF)Grey body radiation phenomena�Effect of scaleEffect of scale. Experiments (DF)

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