Development of a 300 cm² stack for automotive applications

Zentrum für BrennstoffzellenTechnik GmbH

Dr.-Ing. Jörg Karstedt, Coordinator Emobility

World of Energy Solutions,

Stuttgart, 6.10.2014

Development of a 300 cm² stack

for automotive applications

© by ZBT – all rights reserved. Confidential – no passing on to third parties 2

ZBT – Development of a 300cm² stack for automotive applications

Content

ZBT – a brief introduction

Powertrain configurations with battery and fuel cell

Development of a 300cm² stack for automotive applications

– Component benchmarking

– BPP design

– CFD simulation and flow measurements

– Flowfield benchmark

– BPP manufacturing

– Sealing

– Testing

Conclusion



Content





– BPP design




– Sealing

– Testing

Conclusion



The fuel cell research center

The fuel cell research center :

Research and development of fuel cells, hydrogen

and battery technology

Focus on industry demand

Independent service provider

100 full time employees + 40 students

Infrastructure:

1200 m² laboratory

4 confidential laboratories with 220 m²

Flexible testbenches with advanced measurement and analytics

3 climatic chambers incl. vibration testing

First accredited testing laboratory for fuel cells

120 m² injection molding/compound laboratory

Prototype production line



Content





– BPP design




– Sealing

– Testing

Conclusion



OEM commercialization plans

source: Linde 2013



BEVs, FCVs and Fuel Cell Plug-In Hybrids

Emission free

Low Noise

Energy Diversity

Advantages

Challenges

Applications

Design criteria

Battery

Fuel Cell System

Highest TTW efficiency

Low operating cost

Private charging

High density H2 infrastructure

Increased operating cost

Battery System

Fuel Cell System

High energy, > 15 kWh

-

High power, ~ 1.5 kWh

High performance, > 80 kW

State of the art range, comfort,

refuelling time

High continuous power

Limitations range, charging

time, comfort

Public charging

Range

-

Peak power

Performance

Urban traffic High performance long distance

(>120km/h, SUVs)

Battery Electric Vehicle Fuel Cell/Battery Hybrid

source: BMW source: Toyota



Operating experience DOE field trial

Program:

7 year duration

4 OEMs, 183 fuel cell vehicles

5.8 mio. km, 500.000 individual trips

System operation:

Low fuel cell power operation dominant

Fuel cell systems rarely operated at max. power

Fuel cell downsizing enables significant cost

reductions

source: National Fuel Cell Electric Vehicle Learning Demonstration Final Report, NREL 2012

> 90% below 40% max. fuel cell power

> 95% below 50% max. fuel cell power

Fuel cell system operating power



BEVs, FCVs and Fuel Cell Plug-In Hybrids

Emission free

Low Noise

Energy Diversity

Advantages

Challenges

Applications

Design criteria

Battery

Fuel Cell System

Highest TTW efficiency

Low operating cost

Private charging

High density H2 infrastructure

Increased operating cost

Battery System

Fuel Cell System

High energy, > 15 kWh

-

High power, ~ 1.5 kWh

High performance, > 80 kW


refuelling time

High continuous power

Limitations range, charging

time, comfort

Public charging

Range

-

Peak power

Performance

Urban traffic High performance long distance

(>120km/h, SUVs)

Battery Electric Vehicle Fuel Cell/Battery Hybrid

High energy, ~ 10 kWh

Low cost, ~ 30 kW


refuelling time

Low operating cost

Private charging

Medium density H2

infrastructure

Limited continuous power

Optimized TCO

Average power demand

Low-cost, emission free long

distance emobility

Fuel Cell Plug-In Hybrid

source: FEV source: BMW source: Toyota



The case for Fuel Cell Plug-In Hybrids

Optimal degree of hybridization of fuel cell vehicles depends on cost development of

battery and fuel cell

Fuel Cell Plug-In Hybrid focuses on low-cost fuel cell system

Fuel cell system must provide average vehicle power demand to ensure unlimited long-

distance emobility

Battery electric operation covers short-distance

driving w/ highest efficiencies, lowest operating

cost

High value fuel hydrogen is used for long-

distance emission free mobility

source: FEV



BREEZE: Stack development for automotive applications

Project Partners: With financial support from:

Zero emissions during fuel cell operation

Significant NVH advantages compared to ICE

High efficiency

Heat available for cabin heating

Reduction of battery capacity

Re-fueling possible in approx. 3 min. source: FEV



Packaging of BREEZE fuel cell system within demo vehicle

Hydrogen Tank Fuel Cell System

source: FEV



BREEZE fuel cell stack and system specification

System:

Dimensions: 750x520x400 mm

Weight: 80-100 kg

Fuel: Hydrogen 700 bar

Refuelling time: 3 min.

Boost converter to battery voltage

Water/glycol coolant loop with automotive components

Electrically driven automotive radial compressor

Stack:

Stack power output: 33 kW, 325 A, 100 V (nom. Load)

Operating temperature: 80

C

Operating pressure: 2 bar(a)

Cell pitch: 1,2 mm

Metallic bipolar plates

No cathode humidification

Cast aluminum endplate with integrated balance of plant

components

source: FEV



Content





– BPP design




– Sealing

– Testing

Conclusion


MEA Benchmark

Characterization of MEAs for specified operating conditions

– Temperature

– Pressure

– Humidity

– Stoichiometries

High performance ZBT testcell based on Baltic qcf technology

Gradient free ZBT testcell

Coating Benchmark

Extensive BPP/Coating characterization technologies available at ZBT

– Mechanical: Tensile/Flexural

– Electrical: Conductivity and contact resistance

– Corrosion current

– Hydrogen permeation

– Thermal conductivity

– Weight/Density

– In-situ durability tests

Stack development for automotive applications

Benchmarking of MEAs and coatings


Close cooperation between stack developers and BPP

manufacturers

Optimized implementation of stack requirements

regarding the bipolar plate design and the

manufacturability of the bipolar plates

– Flowfield layout

– Gas distribution zones

– Port dimensioning

– Sealing design

– Cooling design

Output: Initial CAD design of bipolar plate


Design development bipolar plates


Optimization of flowfield, gas distributors and ports with CFD-

simulation

– Pressure losses

– Flow velocities

– Flow distribution

In-house flow lab at ZBT: Comparison of simulation and

measurements

– µ-PIV analysis to determine flow in the channels of the

bipolar plates

– Validation and optimization of CFD-simulations


CFD flowfield optimization and µ-PIV flow measurements


In-house manufacturing of sample flowfield geometries by

micro-milling

1:1 reproduction of typical stamping/hydroforming flowfield

geometries (tolerances down to 2µm)

Evaluation of flowfield performance in standardized testcells

Design changes can be validated „online“

– Reduction of development time

– Elimination of tooling cost


Online flowfield performance evaluation: Flowfield benchmark



Results flowfield benchmark

70

C

2 bara

Cathode dry

Anode 50% RH



Bipolar plate production process

Hydroforming Semi-shell plate, uncutted Laser cutting

Cut semi-shell

Laser welding

Metallic Bipolar Plates

Production process



Sealing application at ZBT

Automated application of dispensed seals for prototypes

and small numbers of stacks

High design flexibility

High tolerance compensation

No tooling cost

Iterative sealing development

Parameter optimization dispenser

– Needle speed

– Needle height

– Flowrate

Inhouse 3D surface metrology

– Sealing height and tolerance

– Sealing width and tolerance

– Quality of sealing in radii, starting-points etc.

Development of screen printing for volume production



In-situ testing of stacks

Characterization/Mapping of operating

parameters

Optimization of operating strategies

Durability tests/Ageing investigations and

accelerated stress tests

Cyclic operation

Contamination investigations

Climatic tests



Performance testing of 300cm² stack

80

C / 2 bara

87

C / 3 bara

Cathode dry

Anode recirculation



Content





– BPP design




– Sealing

– Testing

Conclusion


To achieve significant CO2 reductions in the transport sector, a portfolio of powertrain

technologies is required


Conclusion

Emobility enables the utilization of different primary energy carriers, the integration of

renewable energy in the transport sector as well as local emission free, low-noise driving

Fuel cells increase the range and reduce the refuelling time of electric vehicles and can

increase their market acceptance, especially for long-distance emission free driving

Fuel Cell Plug-In Hybrids complement „Full-Power“ FCVs with a focus on operating cost

and available hydrogen infrastructure

ZBT offers engineering services for emobility and fuel cell powertrains in cooperation

with industrial partners

Thank you for your attention!

Contact:

www.zbt-duisburg.de


Dr.-Ing. Jörg Karstedt

[email protected]

+49 (0)203/7598-1178

Hall 2 - E23

Development of a 300 cm² stack for automotive applications

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