iet - institute for energy and transport joint research centre, european commission

San Francisco on 13 September 2011 – 4th ICHS 1

IET - Institute for Energy and Transport

Joint Research Centre, European Commission

Petten - The Netherlands

http://ie.jrc.ec.europa.eu/

http://www.jrc.ec.europa.eu/

B. Acosta, P. Moretto, N. Frischauf, F. Harskamp and C. Bonato

Hydrogen Tank Filling ExperimentsHydrogen Tank Filling Experimentsat the JRC-IET GasTeF Facilityat the JRC-IET GasTeF Facility

International Conference on Hydrogen Safety - 4

September 12-14, 2011San Francisco, California, USA


OUTLINE

Hydrogen storage at high pressures

Fast filling issues

GasTeF: Compressed hydrogen Gas Testing Facility

JRC-IET GasTeF temperature evolution experiment

Experimental results

Next steps


hydrogen storage at high pressures

A type 1 tank, or a standard compressed gas cylinder, is simply a

stainless steel casing holding compressed gas. It has no extra

covering or accessories, except for the coating of paint on the outside that

identifies the contained gas.

A type 2 tank is slightly more durable than a type 1. It has a base cylinder shell made of aluminium or stainless steel, and a partial wrapping around the outside of the cylinder. This wrapping is usually made of a polyester resin containing glass, aramid or carbon.

A type 4 tank is a fully wrapped composite tank with a non- metallic liner. The mechanical loads are therefore only supported by the composite wrapping; the liner itself does not support the loads “non-sharing-load” liner

Type 3 and 4 tanks may also have an additional glass fibre wrappingto protect the tank against external effects

A type 3 tank is a fully wrappedcomposite tank with a metal linermade out of aluminium or stainlesssteel. The composite is wrappedaround the liner. Themechanical loads of the cylinderare supported by both liner and wrapping.


Tank (re)-fuelling Requirements: Avoid exceeding high temperatures in tank Operating range -40 °C to 85 °C

Reasonable short filling duration Max. 3-5 minutes

… however…

The shorter the filling duration The higher the temperatures inside the tank

Higher gas temperatures Higher filling end pressures to assure a “complete tank filling”

Three major risks to damage tank materials: Over-pressurisation

Temperatures higher than the maximum allowed 85 °C (for example SAE J2579)

Over-filling if fuelling occurs at low ambient temperature

The JRC-IET facility GasTeF is an EU reference laboratory designed to carry out performance verification tests of full-scale high pressure vehicle tanks for hydrogen or

natural gas or of any other high-pressure components

fast filling : safety and convenience aspects


GasTeF:Compressed Hydrogen Gas Testing Facility

Half-buried bunker with an attached gas storage area.

Designed to endure a sudden energy release equivalent to 50 kg TNT with a safety factor of 10.

Double walls of heavy-concrete, covered by a 3 meter thick sand layer armoured by geotextile every thirty centimetres

The bunker is closed by a gas-tight inner door and after that by a hydraulically operated 40 tons massive concrete door sliding on Teflon plates

The gas detectors form the heart of the safety monitoring system of the bunker

Operated under remote control – inertised during testing

GasTeF: safe testing of tanks and components


55 kW two-stage pistoncompressor up to 880 bar

H2 / He / CH4

300 bar package

GC and O2 free

H2 detectors2nd Containment

Aluminium Sleeve

1st Containmentpressure vessel The cylinders are placed into a sleeve

which contains an inert gas (He, N2...) and serves as chamber to detect permeation. The H2 level is measured using gas chromatography.

GasTeF layout


-1 0 1 2 3 4 5 6 7 8 9 10

0

50

100

150

200

250

300

350

400

Tank Pressure Bottom Temperature Top Temperature

Test Duration [h]

Pre

ssu

re [b

ar]

0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30

Te

mp

era

ture

[ oC]

Static permeation measurement as a function of time on tanks filled up to 70 MPa and up to temperatures to 100 °C.

GasTeF : fast-filling, cycling and permeation tests on any type of hydrogen (and methane) tanks

Fast-filling cycling, in which storage tanks are fast filled and slowly emptied using hydrogen pressurized up to 70 MPa, for at least 1000 times to simulate their lifetime in a road vehicle. During the cycling process the tank is monitored for leaks and permeation rates using gas chromatography.


Temperature measurement at 3 axial (displaceable) and 5 radial positions

Measurement with He and with H2

Local measurement of H2 temperature

a boom with thermocouples is inserted into the tank

Tank: Raufoss Type 4, 700 bar (29.8 l)


5

6

1

3

2

4

7

H2 inflow

8

T Top

T Bottom

T BossT Line

The temperature evolution experiment is also used to validate software models for tanks (see next presentation)

Experimental data presented hereafter are preliminary results of the on-going testing campaign to map local temperature evolution inside the tank as a function of filling rate under different starting conditions (Ti, pi) and final pressure pf


He versus H2

The graph summarises experiments with different filling rates for different pi, pf and Ti

In general H2 features a smaller temperature increase than He (evident only at high fill rates)

Preliminary Results

-1 0 1 2 3 4 5 6 70

20

40

60

80

100

120

Tem

per

atu

re I

ncr

ease

[oC

]

Fill rate [bar/s]

TC-5 He TC-5 H

2

Position T5:

Axial: 500 – 525 mm from gas inlet

Radial: 15 to 35 mm from liner


The graph summarises experiments with different filling rates and slightly different pi, pf and Ti

Temperature rise influenced by filling rate Variation in temperature rise at a given filling rate is caused by pf, as well as (Ti, pi)

Measured temperatures at the inside and outside of the tank differ significantly

Top_inside

Top_outside

Preliminary Results

Ma

x a

llo

we

d T

0 1 2 3 4 5 60

10

20

30

40

50

60

70

80

90

100

110

120

Fin

al

Te

mp

era

ture

, oC

Fill rate, bar/s

TC-5 T Top

H2

?


After filling finishes, the temperature sharply decreases due to heat transfer from inside the tank to its outer surface

As temperature decreases, pressure does as well and hence it takes several hours to reach equilibrium values

10/12/2010 12:00 11/12/2010 00:00 11/12/2010 12:00 12/12/2010 00:000

10

20

30

40

50

60

70

80

90

100

Pre

ssu

re [

MP

a]

Tem

per

atu

re [

oC

]

Date

P tank Temperature

Long term static pressure tests

30 hours


0 5 10 15 20 25 30 350

10

20

30

40

50

60

70

80

Time [minutes]

Pre

ss

ure

[M

Pa

]

-40-30-20-100102030405060708090

Te

mp

era

ture

[ oC]

Example of fill & emptying cycle

Fill

ing Pressure

holding Emptying

non-linear filling induces a complex (non monotonic) gas temperature evolution as soon as filling is finished, gas temperatures inside the tanks follow a stratification

pattern


a system to cool down the hydrogen when it is supplied to the tank environmental control system to allow simulation of -40°C ambient temperature

Next step: temperature control in GasTeF


control of gas inlet temperature is not easy!

Example of tank temperature dependence on inlet temperature

TC8, Gas inlet temperature

TC5, gas temperature top of the tank

0 20 40 60 80 100 120 140 160 180 200-60

-40

-20

0

20

40

60

80

100

120

140T

emp

erat

ure

s d

uri

ng

fil

lin

g [

C]

Time [s]

0 20 40 60 80 100 120 140 160 180 200-60

-40

-20

0

20

40

60

80

100

120

140T

emp

erat

ure

s d

uri

ng

fil

lin

g [

C]

Time [s]

With pre-cooling

Without pre-cooling

even without cooling, inlet temperature can increase


Conclusions

results show that the maximum gas temperature during filling of a type 4 tank can locally exceed the limit established in current regulations and standards.

The results serve to validate the computed fluid dynamic modelling of the fast filling process, also performed at JRC-IET – See next presentation!

First results suggest that the low thermal conductivity of the plastic liner limits the effect of local temperature peaks on the liner itself as well as on the material of the external shell

Is this maximum allowed temperature too limiting?Is this “historical” limit justified for the materials used?Is it important to consider the duration of the temperature overshoot?

Next experimental step is to place the thermocouples touching or as close as possible to the tank internal surface to obtain accurate measurements of the liner temperature during filling and emptying

measurements are in good agreement with those found in literature


Thank you for your attentionThank you for your attention

[email protected]

[email protected]


In normal operation the facility runs fully automatically and the tests are operator controlled from a control room situated in an adjacent building

control by PLCs and specific software tools

iet - institute for energy and transport joint research centre, european commission

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