PRESLHY WP3 – rainout experiments - HySafe

PRESLHY experimental workshop 26-06-2020

Pre-normative REsearch for Safe use of Liquid HYdrogen

PRESLHY WP3 – rainout experimentsPRESLHY workshop, 26-06-2020


Contents Experiment overview Release data Near-field dispersion Far-field dispersion


Project team

Jonathan Hall, Kieran Lyons, Mark Royle, Deborah Willoughby, Graham Atkinson, Andrew Tooke, Keith Tremble, Trystan Lang, Phil Hooker, Gary Dobbin


Aims The main objective of this series of experiments was to

investigate the propensity for rainout to occur when LH2 is released from elevated positions.

This included: vaporisation characterisation of the flow at the point of release dispersion of the gaseous hydrogen cloud (near and far field) capacity for these releases to form pools


Experimental overview


Experiment overview


Experimental setup

• Green: LH2 release station

• Yellow: tanker and vent stack

• Blue: the near-field array

• Red: far-field stands


Experiment overview

PT1 PT2

TC4

TC2

MFM

TC3

To vent

TC1

Release Near-field dispersion

Far-field dispersion

Temp, Conc

Temp, Conc


Experiment list

Trial No Test No Date Time of start Array location

Far Field sensor location Additional Notes Resistance

1 3.5.3 11/09/2019 15:16:54 Standard Option 2a Commissioning test. 1.42x106 Ω2

2 3.5.1 11/09/2019 15:58:09 Standard Option 2a Commissioning test. 1.06x107 Ω2

3 3.5.1 12/09/2019 11:45:31 Standard Option 2a Good conditions. 1.02x106 Ω2

4 3.5.2 12/09/2019 12:08:57 Standard Option 2aFist footage of solid air around nozzle.

1.06x107 Ω2

5 3.5.3 12/09/2019 14:34:20 Standard Option 2a 2.48x106 Ω2

6 3.5.7 12/09/2019 15:35:30 250mm offset Option 2a

7 3.5.8 12/09/2019 16:10:18 250mm offset Option 2a0.7m radius pool formed with solid deposit.

8 3.5.8 13/09/2019 10:32:55 250mm offset Option 2a 2.07x107 Ω2

9 3.5.9 13/09/2019 11:11:19 350mm offset Option 2a Baffle 160mm from release. 2.72x104 Ω2




13 3.5.17 13/09/2019 14:33:43 250mm offset Option 2a 1.2m radius pool formed.


15 3.5.18 13/09/2019 15:23:26 250mm offset Option 2a Baffle 180mm from release.

16 3.5.4 17/09/2019 11:02:07 Standard Option 2b 3.14x104 Ω2

17 3.5.5 17/09/2019 11:24:11 Standard Option 2b

18 3.5.6 17/09/2019 11:41:45 Standard Option 2b

19 3.5.4 18/09/2019 10:57:26 Standard Option 2a 1.03x107 Ω2

20 3.5.5 18/09/2019 11:18:55 Standard Option 2a

21 3.5.6 18/09/2019 11:40:06 Standard Option 2a

22 3.5.13 18/09/2019 14:57:25 Standard Option 2a Releases carried out at 4.5 bar.



25 3.5.13 18/09/2019 15:47:58 Standard Option 2a Releases carried out at 4.5 bar. 1.03x107 Ω2

Test No Release Orientation Release Height Above Ground

(m)

Orifice Diameter (mm)

Pressure (barg)

3.5.1 Horizontal 0.5 25.4 1

3.5.2 Horizontal 0.5 12 1


3.5.4 Horizontal 1.5 25.4 1



3.5.7 Vertical Up 0.5 12 1

3.5.8 Vertical Down 0.5 12 1

3.5.9 Horizontal + obstruction

0.5 12 1

3.5.10 Horizontal 0.5 25.4 5

3.5.11 Horizontal 0.5 12 5


3.5.13 Horizontal 1.5 25.4 5

3.5.14 Horizontal 1.5 12 5


3.5.16 Vertical Up 0.5 12 5

3.5.17 Vertical Down 0.5 12 5

3.5.18 Horizontal + obstruction

0.5 12 5


Data acquisition and processing Clean and synchronise the data to

a common time base, convert to meaningful units: Pipework pressures & temperatures Near field concentration &

temperatures 31 hydrogen sensors, 24 thermocouples

Far-field concentration & temperatures 30 hydrogen sensors, 30 thermocouples

Flow meter Weather stations Current & resistance

Video Drone, thermal & high speed

Sensor Manufacturer Model Range AccuracyPipework

thermocouplesTC Direct 1.5 mm Type T

Mineral insulated

–200 to 350°C ±1.5% of Reading

Near‐field thermocouples

TC Direct 1.5 mm Type T Mineral insulated


Far‐field thermocouples

TC Direct 1.5 mm Type T Grounded

Chamfered tip


Pressure Wika IS‐3 0‐10 barg ±0.5% of Full Scale

Tank Pressure N/A Dial gauge 0‐15 barg Visual Mass flow Emerson Micro Motion

Coriolis meter0‐7.5 kg/s ±3% of Reading*

H2 concentration

Xensor XEN‐5320 0‐100 Vol % ±3% of Full Scale

H2 concentration

Dräger Xam 5000

XXSH2 HC

0‐4 Vol % ±2% of Reading

H2 concentration

Dräger Xam 5000

Cat‐Ex 125

0‐100% LEL ±1% of Reading

H2 PPM Dräger Xam 5000

XXS H2

0‐2000 ppm ±1% of Reading

O2 depletion Dräger Xam 5000

XXS O2

0‐25 Vol % ±1% of Reading

Near‐field weather station

PCE Instruments

PCE‐FWS‐20 0‐240 km/h

10‐90 % humidity

Indicator

Far‐field wind sensor

Gill Instruments

Windsonic 0‐60 m/s

0‐359°

±3% of Reading

±2°Far‐field humidity sensor

Skye Instruments

SKH 2053 0‐100 %

‐20 to 70°C

±2%

±0.05°


Release station

Electrically isolated section

Flowmeter

Release/recirculation valves

Local weatherShield (not used for dispersion tests)


Experiment procedure Condition LH2 in tank

Flatten the fluid by venting gaseous H2 from the tanker Allow LH2 into the heat exchanger until the desired pressure is

reached Purge the pipework with N2 then warm H2

Initiate recording and prepare triggers Implement safety zones and open manual release valve Operate remote release valves Stop release and complete post-test tasks


Release system measurements Temperatures

“Warm” temperatures logged as CJC compensated temperature “Cold” temperatures (pipework, near-field array) logged as

voltage Voltage converted to temperature using cold junction

measurement and lookup table Thermocouples in pipework not indicating BP for LH2

Post-test investigation of thermocouples conducted using LN2: low temperature error found on thermocouples in pipework (TC1-5

only), error increases as temperature decreases, and investigation reported in D3.6.


Release system measurements

Mass flow meter Extensively modified to help cope with the conditions Mass flow output based on factory calibration for expected

temperatures Drive gain provides useful information Density can be derived from measurement of tube frequency

(not in two phase flow cases)

∝ 2 tube mass (volume, density, temperature)

tube stiffness (temperature) tube period


Release system measurements How much LH2 flows out? What state is it in?


Flow rate calculation Mass flow rate calculations completed and reported:

mass flow rates derived from a combination of flow meter and calculations based on pressure data

results included in latest version of deliverable 3.6

Pressure Nozzle diameter Mass flow

5 bar 6mm ( ¼ ”) 90‐100 g/s

5 bar 12mm ( ½”) 265 g/s

5 bar 1” (open pipe) 298 g/s

1 bar 6mm ( ¼ ”) Unknown

1 bar 12mm ( ½”) 104‐107 g/s

1 bar 1” (open pipe) 135‐144 g/s


Flow rate plots

0

50

100

150

200

250

300

0 50 100 150 200 250 300

Mass flo

w (g

/s)

Time (seconds)

Test 11

Test 13

Test 14

Test 15

MFM measurements5 bar, 12 mm nozzle

‐10

0

10

20

30

40

50

60

70

0

5

10

15

20

25

30

1 51 101 151 201 251 301

Driv

e gain % and

den

sity (k

g/m3)

Mass flow (g

/s)

Time (s)

MFM1_Mass_Flow_RateMFM2_Drive_Gain

Density

MFM measurements1 bar, 12 mm nozzle


Flow composition

Tanker Pressure

Hole size Approx measured

pressure at flow meter

(bar)

Expected vapour

pressure(bar)

Expected phase at meter

Observed phase at meter

5 bar 6mm ( ¼ ”) 4.5 >1.5 liquid liquid5 bar 12mm ( ½”) 2 1 - 1.5 liquid liquid5 bar 1” 1.2 1.2 - 1.5 Marginal

(small gas content)Marginal

(small gas content)

1 bar 6mm ( ¼ ”) <1 >1.5 Gassy Gassy1 bar 12mm ( ½”) 0.5 1.2-1.5 Gassy Gassy1 bar 1” 0.2 1.2-1.5 Gassy Gassy

1 bar/6 mm could not be measured directly or derived due to the flow being predominantly gaseous and the subsequent flow rate/pipework pressure drop being too low for the flow meter/pressure transducers to resolve


Rainout/outflow summary Rainout did not occur during the established flow of these releases, some

seen after valve closure (probably liquid air) Temperatures did not reach H2 rainout levels at the vent stack Pools can form with vertically downwards releases Flow meter is only effective at higher pressures and smaller nozzle sizes

(i.e. void fraction is low) Heat losses due to flow meter and additional pipework reduced

effectiveness of meter (caused 2 phase flow) PRESLHY data can be used to estimate the flow rate in previous HSE

experiments at approximately 135 g/s


Near-field dispersion Collaboration with National Renewable Energy Laboratory

(NREL) for near-field concentration measurements System of pumped sampling tubes and remote sensors Up to 32 detectors based on thermal conductivity Up to 12 co-located TC’s Deployment of NREL’s system for measurements in the jet


Near-field dispersion


Near-field dispersion In some tests, solid material

accumulated on the sampling point and caused horizontal displacement of the location and possibly interfered with sampling


Near-field dispersion

Correlation of temperature vs concentration for all tests (based on corrected temperatures) on centreline

Values coloured by humidity Values coloured by trial


Far-field dispersion 30 Draeger X-am 5000 units mounted at three heights on

stands in the far field, 0.5, 1.5 and 2.5 m Each instrument contains:

PPM H2 sensor LEL H2 sensor O2 sensor

Each instrument co-located with a thermocouple


Far-field dispersion Some preliminary results Further analysis needed e.g. relationship between H2

concentration and O2 depletion


Dispersion video


Dispersion summary Solid deposits formed around the release point and on impingements

with 6/12 mm nozzles, thought to be solidified air Higher pressures and larger nozzles increase the average hydrogen

concentration in the near-field region, in spite of the mass flow meter under-predicting mass flow rates with certain initial conditions

Transient ignitable pockets (average H2 concentration > LEL) were measured at 14 m distance from LH2 releases through 12 mm holes or larger

Following the initial region, approximately 1.5 m for the 1 bar releases and 3 to 6 m for the 5 bar releases, the dispersion of the hydrogen cloud is heavily dependent of the wind, including transient localised gusts


AcknowledgementsThis project has received funding from the Fuel Cells and Hydrogen 2 Joint Undertaking under the European Union’s Horizon 2020 research and innovation programme under grant agreement No 779613. The HSE work programme acknowledges funding from its sponsors Shell, Lloyd’s Register Foundation and Equinor and instrumentation provided by NREL and Dräger.

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PRESLHY WP3 – rainout experiments - HySafe

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