natural and forced ventilation study in an enclosure ... · calculations performed by effects-sgis...
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International Conference on Hydrogen Safety (ICHS3) Palais des Congrès Ajaccio - FRANCE
16-18 September 2009
NATURAL AND FORCED VENTILATION STUDY IN AN ENCLOSURE HOSTING A FUEL CELL
Marco N. Carcassi, Gennaro M. Cerchiara, Martino Schiavetti, Nicola Mattei.
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The purpose of the experimental work is to determine the conditions for which an enclosure can guest a fuel cell for civil use.
ATEX – Limits.
Zone 0 : Continuous leakage → 25%LEL = 1%H2vol;Zone 1 : Operational release → 25%LEL = 1%H2vol;Zone 2 : Occasional leakage → 50%LEL = 2%H2vol.
CEI EN 60079 - 10“Electrical apparatus for explosive atmospheres
Guide for classification of hazardous areas”
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The fuel cell and the leakage monitoring system
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Fuel Cell - Penta H2
PerformanceNet electric power: 1 to 5 and IdleVoltage:120 or 220 VAC
Hydrogen SupplyHydrogen Grade: Grade 5.5 (EU)Inlet pressure: 2-5 baraMass flow: Dead end - pulsingAnode stoichiometric: 1,02Fuel Consumption: 4,2 Nm3/hr at max power
Length 800 mm ; Depth 688 mmHeight 1024 mm; Weight 200 kg
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Small leakage from H2 inletCEI 31 - 35 (2001 - 01) recommendation
Calculations performed by EFFECTS-SGIS 7.3.
PH2 [bar]ΦL[mm]
AL[mm2] 2 2,5 3 3,5 4 4,5 5
0,56 0.25 18,25 22,76 27,34 31,92 36,50 41,08 45,66
0,8 0.50 36,72 45,89 55,12 64,14 73,37 82,76 91,62
1.13 1.00 73,74 91,18 109,36 128,13 146,30 164,77 183,25
GH2[nl/min]
ΦL = H2 Leakage Diameter for pipelines < 150 mm the leakage Area is AL = 0.25 mm2
ΦP = 6 mm
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Leakage Monitoring System
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The CVE hosting the fuel cell and the vent system
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Fuel cell PentaH2 installed inside CVE Particular of the Vent 1 (central)
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Size and location of Vent 1(Side A) coordinates in [mm];
Vent 1 small = central rectangle AV1s = 0.35 m2;
Vent 1 big = both rectangles AV1b = 0.70 m2.
Size and location of Vent 2 and Vent 4 (Side C) coordinates in [mm]AV2 = AV4 = 0.14 m2.
AV = Vent Area [m2]
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Small leakage from H2 inlet.
Size of Vent 1: Vent 1 small (V1s) = 0.35 m2 ; Vent 1 big (V1b) = 0.7 m2;Size of Vent 2: 0.14 m2 fixed (V2);Size of Vent 3: 0.35 m2 fixed (V3);Size of Vent 4: 0.14 m2 fixed (V4);Leakage flow in [nl/min]: small (GH2s) = 40 ; average (GH2a) = 90 ; big (GH2b) = 180
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H2 sampling points.Five Channels - %H2vol.a) flow meters;b) sampling pipelines;c) zeolites;d) concentration measurers.
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The geometry of ventilation and ATEX value of
recirculation air flow
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The geometries of the ventilation tests
S1
S2
S4S3 S5
(1) CASE OFV1s
Area [m2]0.35
S1
S2
S4S3 S5
(2) CASE OFV1s – V2Area [m2]
0.35 + 0.14
S1
S2
S4S3 S5
(10) CASE OFV1b – V2 – V3 – V4
Area [m2]0.70 + 0.35 + 0.14 + 0.14
S1
S2
S4S3 S5
(3) CASE OFV1b
Area [m2]0.70
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ATEX Calculus of Qawvalue in all geometries(Natural Ventilation)
QAW = air flow recirculation in Natural Ventilation conditions
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Natural Ventilation Test results
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Test 11-2008-04-02
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Test 12-2008-04-02H2 Flow [l/min] 90
Vent Area [m2] 0.70 + 0.14
Duration of the leakage [s] 373
Direction of the leakage -Y
Coordinates (x ; y ; z) 1200 ; 1900 ; 800
Diameter of the nozzle [mm] 6S1
S2
S4S3 S5
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Empirical model for the calculus of the venting area
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Natural Ventilation Model steps.
To set the ventilation system we need:
NV Geometry KV QAW AV
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Calculus of KV
In Steady State Conditions
During the initial steps of the tests the enclosure volume with homogenous H2 concentration is a fraction KV of the whole internal volume.
H2(P)%vol and QH2 are measured during the experiments
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Test plan for the calculus of KV
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Test plan for the calculus of KV
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Forced Ventilation Tests and results
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Forced Ventilation Tests
Fan Model AX rpm Power
[kW]Voltage
[V]
current intensity
[A]
Diameter[mm]
Air – flow[m3/s]
Coordinates fan centre[x; y; z]
Fan 1 (1375; 0; 2670)254T 1500 0,04 220/380 0,25 260 0.33
Fan 2 (1375; 3220;2670)
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Conclusions
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Conclusions
Where it is possible, it is convenient to use one or more suitable solutions like:
-To reasonably increase the vent areas beyond the minimum value ;-To consider the vent areas for a leak flow reasonably bigger then the minimum; -To incline the roof making the NV easy and efficient;-To install a small fan able to remove the internal mixture from the enclosure.
The limit of 40 l/min of the leakage is relevant for every kind of fuel cell suitable for civil use. leaks beyond 90 l/min would refer to catastrophic leakage and therefore should not be considered with the assumptions made.
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THANK YOU
Marco N. Carcassi, Gennaro M. Cerchiara, Martino Schiavetti, Nicola Mattei.