Fuel cell: from principle to application to the electric...
Transcript of Fuel cell: from principle to application to the electric...
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Fuel cell: from principle to
application to the electric
vehicle
Yann BULTEL, GINP
Marian Chatenet, GINP
Laurent Antoni, CEA
Jean-Paul Yonnet, CNRS
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1. Fuel Cell Introduction
2. Fuel Cell – Principle of Operation
3. Fuel Cell Performances
4. Fuel Cell Power System
5. Power Fuel Cell Module Hybridizing
6. Safety issues
7. Fuel Cell Vehicle Example
PLAN
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1. Fuel Cell introduction
Yann Bultel
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Fuel cells are electrochemical conversion systems,
which offer unique characteristics as electrical
power generation systems.
What’s a fuel cell ?
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Heat loss
Electrical power
H2
H2in O2
in / Air
H2Oout
, O2 / Air
ANODECATHODE
What’s a fuel cell ?
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HISTRORICAL CONSIDERATION
1842: Sir William Robert Grove is known as “Father of the Fuel Cell.”
reaction triple contact electrolyte-reactants-catalyst
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1932: F. Bacon, Fuel Cell with an alkaline electrolyte
AFC
Years 50-60 : spatial programs (NASA)First practical use
Gemini : 1 kW PEFC (General Electric)
Apollo : ~10 kW AFC (Pratt & Whitney)
Years 2000 : CEAFuel Cell Vehicle
HISTRORICAL CONSIDERATION
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FUEL CELL TYPES
Fuel Cell types:
Low temperature Fuel Cells: PEMFC: Proton Exchange Membrane Fuel Cell (ambient to 80°C);
PAFC: Phosphoric Acid Fuel Cell (PAFC) (200-250°C);
AFC: Alkaline Fuel Cell (ambient to 80°C).
High temperature Fuel Cells:
MCFC: Molten Carbonate Fuel Cell (600 to 700°C);
SOFC: Solid Oxide Fuel Cell (800 to 1000°C).
Fuel Cell technology for HYCHAIN vehicles is based on the
PEMFC.
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2. Fuel Cell – Principle of
Operation
Yann Bultel and Marian Chatenet
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UNIT CELL BEHAVIOUR
Unit cells form the core of a fuel cell (case of PEMFC): This device converts the chemical energy contained in a fuel
electrochemically into electrical energy:
Hydrogen oxidation at the anode
Oxygen reduction at the cathode
Unit Cell working behaviour
../../../../../Animations_hychain/animation_english/anim_anglais_exe/Fuel_cell_behavior.exe
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UNIT CELL BEHAVIOUR
Electrochemical Reactions (case of PEMFC):
Hydrogen Oxidation:
2 H2 (Dihydrogen)→ 4 H+ (proton) + 4 e- (electron)
Oxygen Reduction:
O2 (oxygen) + 4H+ (proton) + 4 e- (electron ) → 2 H2O (Water)
Whole Reaction:
2 H2 (Dihydrogen) + O2 (oxygen) → 2 H2O (Water)
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UNIT CELL COMPONENT
Unit cell is made of (case of PEMFC): Electrolyte: polymer membrane (Nafion)
Gas Diffusion Electrode
Gas Diffusion Layer
• Carbon cloth/paper
Active Layer
Carbon + Platinum
Unit cell components
../../../../../Animations_hychain/animation_english/anim_anglais_exe/MEA_description.exe
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UNIT CELL COMPONENT
Electrolyte
Materials:
~ Polymer electrolyte;
Example: Nafion -perfluorosulfonic acid PTFE
copolymer (DUPONT)
N-115/117 (130/180 µm)
Properties:
Protons migrations from anode
to cathode;
Gas separator;
Electronic insulator.
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UNIT CELL COMPONENT
Electrolyte
Nafion
Non F-ionomers
N
NN
N
H
H
[ ]n
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Electrode
Active(/Catalyst) Layer:
Materials: ~ Carbon grains supported
Platinum nanoparticles;
Electrochemical reactions (Hydrogen
oxidation and Oxygen reduction).
UNIT CELL COMPONENT
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• Issues
O2 reduction slow and not reversible
• 4 e- reaction non quantitative (peroxides formation)
• high ORR overpotential
high catalysts loadings required
high cost
catalyst utilization ?
Instability of the Pt/C particles
• Solutions
Alloy or composites nanoparticles to improve the 4 e- pathway
Pt-Co/C, Pt-Ni/C
Non-platinum electrocatalysts?
Electrode
Active(/Catalyst) Layer:
Which electrocatalysts for the cathode ?
UNIT CELL COMPONENT
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Electrode
Gas Diffusion Layer:
Materials: ~ Carbon cloth/paper and
Teflon;
Gas supply.
Water removal
UNIT CELL COMPONENT
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GDLSubstrate (C fabric)
Carbon (powder)
Hydrophobic-
porosity-binding
agent (PTFE)
ALElectrocatalyst
Electrolyte
Carbon
Hydrophobic-
porosity-binding
agent (PTFE)
MembraneIonic conducting polymer
Electronic insulator
Barrier to reagent
MEA
UNIT CELL COMPONENT
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Gas Diffusion Layer (GDL)
Reagent feeding
Products draining
(water & reagent excess)
Current collecting
Thermal management
Mechanical support
Active Layer (AL)
Electrochemical reactions
+ function of the GDL
MembraneA & C reagent separation
Ionic transport
Electronic insulator
Mechanical support
MEA
UNIT CELL COMPONENT
150 µm
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Bipolar plate
Electrode Membrane
Assembly
End plate
UNIT CELL COMPONENT
External current collecting
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Bipolar plate:
Materials
Graphite
Metallic
Properties
Electronic current collecting;
Gas distribution;
Heat management.
UNIT CELL COMPONENT
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Serpentine flow field design:
Conventional (a) and interdigitated (b)
gas distributor of PEMFC bipolar plate
UNIT CELL COMPONENT
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1. Serpentine flow field design:l
w
d
Parameter Values
channel width w 0.5-2.5 mm
channel depth d 0.2-2.5 mm
landing width l 0.2-2.5 mm
draft angle 0-15°
UNIT CELL COMPONENT
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UNIT CELL COMPONENT
Single Cell
Gas supply
Exhaust
Gas
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FUEL CELL STACK
The stacking involves connecting multiple unit cells in
series via Bipolar plate to provide:
An electrical series connection between adjacent cells;
Gas barrier that separates the fuel and oxidant of adjacent
cells;
Fuel Cell Stack description
Fuel Cell Stack Principle
../../../../../Animations_hychain/animation_english/anim_anglais_exe/Stack_description.exe../../../../../Animations_hychain/animation_english/anim_anglais_exe/Stack_principe.exe../../../../../Animations_hychain/animation_english/anim_anglais_exe/Stack_principe.exe
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FUEL CELL STACK
Ucell
Electric network: cells in series
Ucell Ucell
n
k
k
cellstack UU1
I
e-
n
k
k
cellstack UIP1
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FUEL CELL STACK
ANODE
CATHODE
O2in / Air
H2in
Gas supply: cells in parallel
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3. Fuel Cell Performances
Yann Bultel
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FUEL CELL PERFORMANCES
Actual Cell Potential:
Activation-related losses (due to kinetics);
Ohmic losses (due electrical resistance);
Mass-transport-related losses (due to diffusion
losses);
../../../../../Animations_hychain/animation_english/anim_anglais_exe/Fuel_cell_performance.exe
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Polarisation curve
Ei=0ORR irreversibility
1
2
3
Cell voltage
U (V)
Current density
i (A/cm2)
Er
1 - Activation overvoltage hact 2 – Ohmic drop hohm 3 – Diffusion limitation hdifElectrocatalysts, Sact Ions and e
- resistance Gas diffusion to the catalyst
(membrane, electrodes)
Gas
diffusionH2
H+
e-
Ionic
resistance
Ohmic
resistance
e- transfer
resistance
(activation)
The triple contact
FUEL CELL PERFORMANCES
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Activation overpotential: Kinetic Tafel Law
h
0
acti
iln
3.2
b
Overpotential Current density
Log(i)
Overvoltage at the
surface of an electrode
h (V)
b : Tafel constant
i0 : exchange current density
Experimental parameters
FUEL CELL PERFORMANCES
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Activation overpotential: Kinetic Tafel Law
FUEL CELL PERFORMANCES
Impedance study of the oxygen reduction reaction on platinum nanoparticles in
alkaline media, L. Genies, Y. Bultel, R. Faure, R. Durand, Electrochimica Acta (2003)
b : Tafel slope
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Internal Resistive losses
Electronic and Ionic conductivity of materials
Nafion: ionic = 5 S m-1 Bipolar plate: ionic = 5000 S.cm
-1
jRj L
V eelectrolytm
mionic
H+
Resistance of the
flow of ions
Resistance of the
flow of electrons
> >
FUEL CELL PERFORMANCES
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Mass Transport limitation:
finite mass transport rates limit the supply of fresh
reactant;
Faraday’s law:
Limiting current density jL
Concentration overpotential:
H2O
GDLAL
O2
SB CCD F n
i
CB
CS
0CD F n
i BL
FUEL CELL PERFORMANCES
h
L
conci
i1ln
nF
RT
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Power density versus current density:
0
0,2
0,4
0,6
0,8
1
1,2
0 0,2 0,4 0,6 0,8 1 1,2 1,4
i / A cm-2
Y /
-
P / W cm-2
U / V
FUEL CELL PERFORMANCES
celle U IW
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Heat production:
OHO2
1H 222
Hr
Electrical
power
Heating rate Maximum efficiency possible
cell
rheat U
F2
HIQ
celle U IW
FUEL CELL PERFORMANCES
2
ohmic I RQ
I Q concact h
I.nF
STQ ityreversibil
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Gas feeding:
Mass transport into a cell
Gas Utilization:
Gas consumption (H2, O2)
and water production is linked
to current the current (/density)
Faraday’s law
FUEL CELL PERFORMANCES
nF
IF react,i [mol.s-1]
nF
iN react,i [mol.s-1.m-2]
../../../../../Animations_hychain/animation_english/anim_anglais_exe/Fuel_cell_flow.exe../../../../../Animations_hychain/animation_english/anim_anglais_exe/Fuel_cell_flow.exe
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Mass and Heat Balances:
PEMFC Stack
Mass Balance:
Heat Balance:
nF
INFF cellout,iin,i
FUEL CELL PERFORMANCES
inoutpiicool TTcmQ
../../../../../Animations_hychain/animation_english/anim_anglais_exe/Stack_flow.exe../../../../../Animations_hychain/animation_english/anim_anglais_exe/Stack_flow.exe
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One species mass balance O2 or H2:
Gas Utilization Rate:
Stoichiometric ratio
nF
IFIFFF out,ireacti,out,iin,i
in,i
out,iin,i
in,i
react,i
iF
FF
F
FU
anode
cathode
Fa,in Fa,out
Fc,in Fc,out
Sti=1 : Stoichiometric conditions
FUEL CELL PERFORMANCES
ireact,i
in,i
iU
1
F
FSt
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Water management:
FUEL CELL PERFORMANCES
Gas channel
H2O Water diffusion
Cathode
Electro-osmotic flow
Gas channel
Anode
H2O, O2, N2
H2O, H2
H2O
F2
ir electroO2H
iF2
2N
dragelectro
O2H
m
c
O2H
a
O2H
O2H
diffusion
O2HL
ccDN
O2Hsat PPevap/cond of Rate
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4. Fuel Cell Power System
Laurent Antoni
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FUNCTIONAL DECOMPOSITION
OF THE FUEL CELL POWER
MODULE
System analysis:
- Numerous possible technical solutions
Depends on the application
On board
Stationary
Portable
Depends on the environment
Temperature
Pressure
Pollutants…
Depends on the user need
General objective (power, durability)
Duty cycle
Analysis / Functional Decomposition
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FUNCTIONAL DECOMPOSITION
OF THE FUEL CELL POWER
MODULE
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FUNCTIONAL DECOMPOSITION
OF THE FUEL CELL POWER
MODULE
FUEL
CELL
CODITIONNING
INLET/OUTLET
ANODE
ELECTRICAL CONVERTORS
EX
TE
RN
AL
EN
VIR
ON
NM
EN
T
EX
TE
RN
AL
EN
VIR
ON
NM
EN
T
FU
EL
TA
NK
COOLING : WATER MANAGEMENT
BUSBATTERIESAUXILIAIRIES
VE
HIC
LE
CO
OL
ING
SUPERVISOR
CODITIONNING
INLET/OUTLET
CATHODE
FUEL
CELL
CODITIONNING
INLET/OUTLET
ANODE
ELECTRICAL CONVERTORS
EX
TE
RN
AL
EN
VIR
ON
NM
EN
T
EX
TE
RN
AL
EN
VIR
ON
NM
EN
T
FU
EL
TA
NK
COOLING : WATER MANAGEMENT
BUSBATTERIESAUXILIAIRIES
VE
HIC
LE
CO
OL
ING
SUPERVISOR
CODITIONNING
INLET/OUTLET
CATHODE
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Highest complexity
Recovery of mechanical energy from compression
Management of the liquid water from humidification
« High pressure » operation
Example of cathode
inlet/outlet subsystem
FILTER COMPRESSOR HUMDIFIER
CATHODE
EXTERNAL
ENVIRON-
MENT
SUPERVISOR
EXPANSION
TURBINE
SEPARATOR /
CONDENSER
COOLING /
WATER MANAGEMENT
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Anode inlet/outletInfluence of the fuel choice
On the FC system architecture
On-board molecular hydrogen
« dead-end » architecture
Recirculation circuit
Hydrocarbon reforming
Steam Reforming or SR, which is endothermic and leads to the
best efficiencies but consumes water)
Partial Oxidation or POX, which is exothermic and is appropriate for
heavy hydrocarbons,
AutoThermal Reforming or ATR, a combination of both, facilitating
the thermal management of the steam-reforming unit
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Impact on the power module
architecture
A)HUMIDIFICATOR
ANODE
CONDENSEURRECIRCULATOR
DETENDEUR
PURGE
COOLING/HUMIDIFICATION
SUPERVISOR
HYDROGEN
TANK
EXTERNAL
ENVIRONNMENT
HUMIDIFIER
ANODE
CONDENSERRECIRCULATOR
EXPANSION
Draining
COOLING/HUMIDIFICATION
SUPERVISOR
HYDROGEN
TANK
EXTERNAL
ENVIRONNMENT
Recirculation architecture
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Impact on the power module
architecture
B)
DETENTEHYDROGEN
TANK
PURGE
ANODE
EXTERNAL
ENVIRONNMENT
SUPERVISOR
EXPANSIONHYDROGEN
TANK
DRAINING
ANODE
EXTERNAL
ENVIRONNMENT
SUPERVISOR
Dead-end architecture
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Impact on the power module
architecture
The complexity of the system is strongly increased in the
case of the reforming
C)
VAPORISOR
METHANOL
TANK
WATER
TANK
BURNER
STEAM-
REFORMER
SELECTIVE
OXIDATION
ANODE
EXTERNAL
ENVIRONNMENT
SUPERVISOR
VAPORISOR
METHANOL
TANK
WATER
TANK
BURNER
STEAM-
REFORMER
SELECTIVE
OXIDATION
ANODE
EXTERNAL
ENVIRONNMENT
SUPERVISOR
Steam-reforming of methanol/methane architecture
../../../../../Animations_hychain/animation_english/anim_anglais_exe/Steam_reforming.exe../../../../../Animations_hychain/animation_english/anim_anglais_exe/Steam_reforming.exe
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Impact on the power module
architecture
Fuel architecture: Fuel Storage
The volume and weight of
each of these systems is
compared to gasoline,
methanol and battery storage
systems (each con-taining
(1 044500 kJ) of stored energy
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Impact on the power module
architecture
Fuel architecture: CO2 emission
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Performance and efficiency
Efficiency of the energy conversion
Efficiency is defined as the relationship between the
“product” of the action to evaluate and a reference
which should be defined.
For the fuel cell, as a converter of chemical energy in
electrical energy, the product is in general the provided
electric power
inlet) (systeme injectedPower
outlet) (system providedPower E fficiency
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Performance and efficiency
Expression of the energetic efficiency
• The efficiency of the energy conversion in the stack compared to the HHV of fuel is written:
• If Stcomb is the ratio between the entering fuel flow and that consumed for the production of the usable current I
• where UHHHV is a symbolic “voltage” corresponding to the total energy
conversion of combustion into electrical energy what cannot be done. This symbolic voltage is usually called thermo neutral voltage
HHVe,comb
stackstack
energyHN
IU
h
pilecell
e,comb
combI
F2
n
NSt
HHV
cell
combHHV
pile
combcell
energy
HU
U
St
1
F2
H
U
St
1
n
1
h
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Performance and efficiency Expression of the energetic efficiency
The power delivered by the system never equals that of the stack as many components consume part of the energy produced by the stack Air compressor
Pumps (cooling, recirculation H2)
Actuators (valves, pressure regulators)
Sensors (pressure, temperature, flow)
Supervisor
Power electronics
Practical efficiency of a system is :
HHVe,comb
auxauxstackstack.convert
energyHN
IUIU
hh
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0
10
20
30
40
50
60
70
0 10 20 30 40 50
Puissance nette (kW)
Re
nd
em
en
t (%
)
Pile à combustible seule
Groupe électrogène
Performance and efficiency Expression of the energetic efficiency
The practical system efficiency expression is:
HHVe,comb
auxauxstackstack.convert
energyHN
IUIU
hh
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5. Power Fuel Cell module
Hybridizing
Jean-Paul Yonnet
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Different order of power of vehicles: Tarins: 4 to 6 MW (Megawatts), fast train like TGV: 6 to 8 MW,
Trucks and Buses : 200 to 600 kW (kilowatts),
On-road cars: 50 to 100 kW,
City cars: 20 to 30 kW,
Small vehicles: go-kart, scooters, etc: 0.5 to 5 kW.
Energy Flux: Hybrid vehicle have two types of energy source:
• A temporary electrical energy storage (Batteries or Supercapacitors),
• A second energy source: Internal Combustion Engine (ICE) or Fuel Cell (FC).
VEHICLE POWER
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Power FC module hybridizing
Several objectives To reduce the Fuel Cell (FC) stack power,
To manage the high power peak transients,
To recover the braking energy,
To increase the efficiency at low power.
Different hybridizing levels depending on the transient electric storage capacity Some % of the FC system power,
• Use of batteries for e.g. starting.
Up to 50% of the FC system power,
• The batteries manages the power peak demands.
Higher then 50% of the FC system power,
• The FC is mainly used to supply the average energy consumption.
The FC system definition will strongly depends on the global
architecture
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HYBRID VEHICLE
Hybrid operation:
One solution is to make a mechanical coupling of the axis of an
ICE (Internal Combustion Engine) and an Electric Motor. It is
called the Parallel Hybrid, or Mechanical Transmission Hybrid.
Parallel Hybrid Vehicle
Advantages and disadvantages of Parallel Hybrids:
• Electric machine and the associated converter are
dimensioned only for the electric power,
• The rotation speed is given by the wheel speed,
• Lower cost of the electric parts.
../../../../../Animations_hychain/animation_english/anim_anglais_exe/Parallele_hybrid.exe../../../../../Animations_hychain/animation_english/anim_anglais_exe/Parallele_hybrid.exe
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HYBRID VEHICLE
Hybrid operation:
When the additional power source is a Fuel Cell, it cannot
create mechanical power. It can supply only electric power.
It is why only Series Hybrids are possible with Fuel Cell.
Series Hybrid Vehicle
Advantages and disadvantages of Series Hybrid:
• More simple mechanical structure,
• The additional power source can be used at its optimal
operation point,
• But the converter must be
designed for the maximum
power.
../../../../../Animations_hychain/animation_english/anim_anglais_exe/Serie_hybrid.exe../../../../../Animations_hychain/animation_english/anim_anglais_exe/Serie_hybrid.exe
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In the power part of a Fuel Cell vehicle, you have :
An Electrical Network at medium or high voltage (80V to
500V),
One or several Electrical Machines for the wheel propulsion,
Power Electronics to make all the energy conversions,
Batteries (or other type of electric energy storage),
the Fuel Cell,
the Hydrogen storage.
Operation of a FC Vehicle
FUEL CELL VEHICLE
../../../../../Animations_hychain/animation_english/anim_anglais_exe/Fuel_cell_vehicle.exe../../../../../Animations_hychain/animation_english/anim_anglais_exe/Fuel_cell_vehicle.exe
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6. Safety issues
Yann Bultel
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HYDROGEN SAFETY
1. Hydrogen is odourless, colourless, tasteless and non-
toxic.
2. Hydrogen has a very wide range of flammability.
3. Hydrogen is very buoyant and diffuses rapidly in air.
4. Hydrogen has very low ignition energy.
5. Hydrogen burns with a pale blue, nearly invisible, flame.
6. Hydrogen is non-toxic and non-poisonous.
Hydrogen Methane Propane Gasoline
Lower flammability limits in air (%) 4 4.4 1.7 1.1
Upper flammability limits in air (%) 75 17 10.9 6.7
Minimum ignition energy (mJ) 0.017 0.290 0.240 0.240
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HYDROGEN SAFETY
Hydrogen flame:
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7. Fuel Cell Vehicle Example
Yann Bultel
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Industrial hydrogen Hydrogen, vector of energy
HYDROGEN INFRASTRUCUTURE
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Goal :
An appropriate Hydrogen infrastructure
HYDROGEN INFRASTRUCUTURE
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HYCHAIN VEHICLES
PAC
Hydrogen
storage
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HYCHAIN VEHICLES
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Application to wheelchair
Application to vehicle
HYCHAIN VEHICLES
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Hychain Mini-trans
Castilla León
SPAIN
Emilia Romagna
ITALY
Emscher -Lippe
GERMANY
Rhône-Alpes
FRANCE