experimental study of hydrogen releases in the passenger compartment of a piaggio porter van

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

EXPERIMENTAL STUDY OF HYDROGEN RELEASES IN THE PASSENGER COMPARTMENT OF A PIAGGIO PORTER VAN

EXPERIMENTAL STUDY OF HYDROGEN RELEASES IN THE PASSENGER COMPARTMENT OF A PIAGGIO

PORTER VAN

M. Schiavetti, V. Mattoli, G. Lutzemberger, P. Dario and M. Carcassi

Dipartimento di Ingegneria Meccanica, Nucleare e della Produzione Dipartimento di Ingegneria Meccanica, Nucleare e della Produzione (DIMNP),(DIMNP),

University of PisaUniversity of Pisa

Università di Pisa



“FILIERA IDROGENO” PROJECT

The project promotes the development and testing

of mobility systems powered with H2

SPONSORS:

One of the objectives of the project was to replace the electric powered system of a Piaggio porter with a H2 system and perform driving tests

Italian Ministry of University MIUR



PIAGGIO PORTER VAN MAIN FEATURES

Seating capacity 2/4

Number of doors 4

Total length 3370 mm

Total width 1395 mm

Height 1870 mm

Wheel spacing 1810 mm

Loading capacity 3/1,4 m3

Lifting power 540 kg

Loading area 1270x1760

Height of the load area from ground

560 mm

Max. speed (electric) 52-57 km/h

Max. speed (H2) 80 km/h

Range (electric) 110/137 km

Range (H2) 180 km

Vehicle mass (empty)

(loaded)

1095 kg

1535 kg

Electric motor power 22 kW

Fuel cell power 13,2 kW



HYDROGEN SYSTEM DESIGN



SAFETY CONSIDERATIONS

• Vehicle was not designed to host the H2 system

• Body kit could promote the accumulation of H2 under the vehicle

• Air ventilation openings directly connect the passenger compartment with the external air under the vehicle

• The ventilation air intake openings were located in front of the fuel cell

(Additional risks for the passengers due to the installation of the H2 system)



Three main scenarios were identified

Scenario 1: H2 may accumulate inside the passenger compartment during long term stops of the vehicle (diffusive leak)

Scenario 2: H2 may enter inside the passenger compartment during the stops of the vehicle as a consequence of a major leak from the pipelines

Scenario 3: During brief stops with the ventilation system on, the released H2 may be sucked inside the passenger compartment by the ventilation system



EXPERIMENTAL SET-UP



EXPERIMENTAL SET UP: RELEASE POSITIONS

Scenario 3: Releases inside the ventilation fan

Flow rate: 0.05 - 0.215 g/sTotal H2 released: 1.3 – 15 g

Scenario 2: Releases under the vehicleFlow rate: 0.215 g/s Pressure: 5 barTotal H2 released: 1.3 – 2.8 g

Scenario 1: Releases inside the vehicleH2 produced by a small electrolyzer Release flow rate: 3 10-5 g/sRelease duration: 3 h



EXPERIMENTAL SET UP: Sensors Position

• Under the vehicle

5 sensorsMSA 9010 Range: 0-20% H2 vol.

• Inside the vehicle

X [mm] Y[mm] Z[mm]

Sensor 1 350 1030 1864

Sensor 2 400 530 1854

Sensor 3 -150 540 1868

Sensor 4 900 540 1869

X [mm] Y[mm] Z[mm]

Sensor 1 -400 540 480

Sensor 2 2410 540 270

Sensor 3 900 1030 410

Sensor 4 900 50 390

Sensor 5 -600 540 270

8 sensors coupled in 4 positions

- KHS-200 MEMS micro- pellistor Range: 0-4% H2 vol.

- Synkera trace hydrogen sensors P/N701 Range: 10-1000 ppm



SCENARIO 1: Diffusive leaks

Tests where conducted to check if H2 would accumulate inside the vehicle

Hydrogen release rate: 3 10-5 g/sRelease duration: 3 h

H2 was released close to the right ventilation opening which directly connects the passenger compartment with the external air under vehicle

Release position



• Almost steady state conditions were reached (H2 concentration close to 400 ppm)

• No accumulation inside the vehicle

H2 exits the vehicle through the gasket of the rear door on top of the canopy



Test#

Flow rate[g/s]

Release time [s]

Hydrogen released

[g]

Max. H2 vol. conc. under the vehicle

[%vol]

Max. H2 vol. conc. inside the vehicle [%vol]

Ventilation flow rate

[m3/h]

Release position R1 (at the front of the vehicle)

1 0.215 6 1.35 2.2 0.7 0

2 0.215 10.5 2.41 5.85 1.6 0

3 0.215 6 1.33 3.64 0.6 0

4 0.215 6 1.44 3.62 0.65 0

5 0.215 6 1.37 3.64 0.6 0

6 0.215 6 1.46 3.82 0.6 0

7 0.215 10.5 2.45 6 1.7 0

8 0.215 11 2.5 3.2 1.7 0

9 0.215 11 2.43 4.2 1.8 0

10 0.215 12 2.84 6.3 1.8 0

11 0.215 10.5 2.39 5.5 0.15 170

12 0.215 10.5 2.4 5.1 0.15 250

Release position R2 (at the middle of the vehicle)

13 0.215 6 1.41 7.4 none 170

14 0.215 6 1.39 6 0.2 0

15 0.215 10.5 2.43 8 0.35 0

SCENARIO 2: Releases under the vehicle



H2 released at the front (release position R1) reaches the passenger compartment easier

Total H2 released: 2,4 g(pipe H2 content of 1,4 g

+5 s of H2 release with 0,2 g/s flow

rate)

The pipe rupture with the correct closure of the bottles (5 s) does not release enough H2 to create a flammable atmosphere inside the vehicle

0

0,2

0,4

0,6

0,8

1

1,2

1,4

1,6

1,8

0 100 200 300 400 500 600

Time [s]

Co

nce

ntr

atio

n [

%vo

l]Release position R1

Release position R2

Release time



Ventilation fan activated Decrease of H2 concentration under the vehicleH2 is sucked in the compartment by the ventilation

Tests affected by the presence of wind

Wind does not affect H2 concentration measurements inside the vehicle

Part of the released H2 is sucked in by the ventilation fan and mixes with the intake air. H2 exits the compartment from the ventilation openings.

Release position R1 H2 under the vehicle

Release position R1H2 inside the vehicle

Ventilation fan de-activatedH2 enters the compartment from the ventilation openings



0

0,5

1

1,5

2

50 100 150 200 250 300 350

Time [s]

Co

nc

entr

ati

on

[%

vol]

Test 7 CH1

Test 11 CH1

Test 12 CH1

Effect of ventilation system• Test 7 (ventilation system off)• Test 11 (ventilation system on 170 m3/h)• Test 12 (ventilation system on 250 m3/h)

Total H2 released: 2,4 gRelease position R1

H2 measurements

at sensor 1

Release time



Test#

Flow rate[g/s]

Release time [s]

Hydrogenreleased

[g]

Max. Conc. UNDER the

vehicle [%vol.]

Max. H2 vol. conc. INSIDE

the vehicle[%vol.]

Average Conc. INSIDE the

vehicle[%vol.]

Ventilation flow rate

[m3/h]

16 0.215 6 1.29 0.2 3,8 0.4 270

17 0.21 11 2.31 0.4 4.5 0.8 270

18 0.206 21 4.24 0.8 4.7 1.5 270

19 0.206 43 8.86 1.4 5.3 3 270

20 0.206 59.5 12.52 2.2 5.6 4 270

21 0.104 61 6.33 1.2 3 1.1 270

22 0.104 150.5 15.72 1.8 3.8 2 270

23 0.05 61.5 3.08 0.6 1.4 0.5 270

24 0.05 301.5 15.08 1.4 1.9 1 270

Scenario 3: Releases inside the ventilation system (from the right “defrost” ventilation opening)

Pure airAir – hydrogen

mixture



Scenario 3: Releases inside the ventilation system – General behaviour

The ratio hydrogen/air flow rates determines the hydrogen steady state concentration inside the vehicle



TEST 23and

TEST 24

0,0

0,2

0,4

0,6

0,8

1,0

1,2

0 50 100 150 200 250 300 350

Time [s]

Co

nc

entr

ati

on

[%

vol]

Test 23

Test 24

0,0

0,2

0,4

0,6

0,8

1,0

1,2

0 50 100 150 200 250 300 350

Time [s]

Co

nc

en

tra

tio

n [

%v

ol]

Test 23

Test 24

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0 50 100 150 200 250 300 350

Time [s]

Co

nc

en

tra

tio

n [

%v

ol]

Test 23

Test 24

0,0

0,5

1,0

1,5

2,0

2,5

0 50 100 150 200 250 300 350

Time [s]

Co

nce

ntr

atio

n [

%vo

l]

Test 23

Test 24

Test 23H2 flow rate: 0.05 g/sRelease time: 61.5 s

Test 24H2 flow rate: 0.05 g/sRelease time: 301.5 s

Time to reach nearly steady state conditions inside the compartment is approximately 5 min



CONCLUSIONS (1/2)• Scenario 1: Releases inside the vehicle (diffusive leaks)

- Concentration inside the vehicle reached an asymptotic value of 400 ppm and further increase was found no possible in this kind of scenario.

• Scenario 2: Releases under the vehicle

-Concentration inside the vehicle was always lower than the 50%LEL when up to 2,4g of H2 was released.- Hydrogen was sucked in the passenger compartment when the release took place in the position closest to the suction opening, however the concentration inside the vehicle was one order of magnitude lower as compared to the cases with the ventilation deactivated.

• Scenario 3: Releases inside the ventilation system

- The ratio hydrogen/air flow rates determines the hydrogen steady state concentration inside the vehicle.

- H2 flow rate of 0.2g/s produce a flammable atmosphere inside the passenger compartment. -Time needed to reach stady state inside the passenger compartment is approximately 300 s.



CONCLUSIONS (2/2)

• No harm to the passenger of the vehicle is possible if the unintended leak is the only undesirable event

• If the release takes place while an independent event is undergoing (i.e. if valves don’t isolate the storage bottles during the stops of the vehicle or when the flow rate exceeds 120% of the maximum or decreases to 0 while the fuel cell is in use) a bigger release can take place and the biuld up of a flammable atmosphere inside the passenger compartment is possible

• Overpressurization of the passenger compartment could prevent the build up of a flammable atmsphere inside the vehicle but care should be taken in the design of the position of the air intake

ACKNOLEDGMENTS

The authors would like to thank Italian Ministry of University MIUR and

“Regione Toscana” forfunding the “Filiera Idrogeno” project, whose

funds have been used for this study



THANK YOU.

Contact Author:

Martino Schiavetti (UNIPI-ITALY)[email protected]

experimental study of hydrogen releases in the passenger compartment of a piaggio porter van

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