RES_V4

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Renewable Energy Sources

Topic: Fuel Cell Modelling

Speaker: P. Bernstein

Date: 02.05.2013

Lehrstuhl Elektrische Netze und Alternative Elektroenergiequellen

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Fuel Cell Modelling

Electrical modelling

Thermal modelling

Electrochemical modelling

Fuel Cell ControllingSingle cell voltage measurement

Current density measurement

Humidity measurement

Fuel cell cooling

Fuel Cell Modelling 2

Structure

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Fuel Cell Modelling

Modelling fundamentals

description of reality through models by

Balance equations

Mass

Charge

Impulse

Energy

Boundary and transition conditions

Source and drain terms

Complex geometry


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e- e-

/

CA,C A,C

F C M E


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Fz

GU R

=

0 I II III

=

0j

jlgbUact

jrUohm =

=

Lconc

j

jln

Fn

TRU 1

ParameterTAFELb

cetanresisrelatedarear

densitycurrentinalargmj

densitycurrentexchangej

L

=

=

=

=0

concohmactcell UUUUU = 0

F C M E


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F C M E0

0

RAKonzRMemRAAkt

CADK

UAGF

RKKonzRKAkt

CKDK

UKGF

UBZ

CMem

RLast

IBZ

0


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F C M E

M

C (, , )

A

1=K

:

2=: C=0

CKDK=0


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c= experimental constant

F C M E


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( )cellcellcell UV48.1IQ =&

F C M


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F C M

in,HH,Bin,Hin,H hHmH 2222 += &&

)g(OHin,airairin,airin,air hxhmH 2+=&&

1000

=

i

iiZFCi

zF

MnIm&

( )ambOOloss TTAQ =&

OH,evapFCcoolingOH Q)T(QQ 22&&&

+=


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F C M


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F C M


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( ), H2O=60C

F C M


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Fuel Cell Modelling - Electrochemical

electrochemical double layer

E - electric field

- potential

H GC


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( ) ( ) ( )

=

reverseforward

UUTR

FzexpUU

TR

FzexpjAj 000

1

B

M

0

F F C


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TAFEL-equation

coherence between fuel cell voltage drop and exchange current atgiven load current

exchange current depends on efficiency of the used catalyst reverse reaction negligible (high over potential)

linear U-j-characteristic

I

Iln

Fz

TRU 0

=

currentexchangeIfactorsymmetry

==

0

anode

I

Iln

Fz)1(

TRU 0

= cathode



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Fuel Cell Controlling

Main control parameters Voltage

Single cell voltage

Stack voltage

Current density Total current

Current density distribution across active surface

Humidity

Humidification of the membrane

Humidification of the gases (hydrogen and oxygen) Temperature

Pressure


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F C C

M


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2008

FC-control

diagnosticsintegration

20072005

FC-system

FC-lab

FC-test systems (0,25-5kW)single-cell measurement

2001

2010-2011

current density

measurement

2009

singel-cell

measurement in

Commercial FC

FC-APU

2001-2002

electrolyzer

equipment systems

2003-2004

material- and

probetesting


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hydrogen tank storage 5 kW fuel cell system 300 W fuel cell test systems


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F C C

69

1:

I=40A

=52

=60C;

2:

I

=100A

=44

=60C


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F C C


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F C C


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F C C

M 32 I 232

1.024 4 26 DC

10 M 3

10H@32 D 420


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i...1n,mjA

Ij

i

1n,m

mem

FC ===

F C C C D

M

I

L M


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Source: T.Chikahisa

?

Identification of dry areas

Prevention of dry-out conditions

Controlling of the volume flows to improve the fuel cell efficiency and

the life-time

F C C C D


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C

Masking method

Measurement of local bounded segments of the MEA

Segmentation method (modified MEA)

Sub-cells

Segmentation of the flow field and the electrodes

Usage of a constant current source

Segmentation method (non-modified MEA)

a. Magnetic loops (current collector board) Modified flow fields

b. Ohmic resistance

Non invasive method

F C C C D


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C 121

F C C C D

( MEA)


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F C C C D


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Absolute humidity

/

: C, K, L

F C C H


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F C C H

behavior of a dry (I) and humidified

(II) PEM membrane during the

supply with hydrogen


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F C C H

H


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F C C H

P:

G

L

C:

E

()

C A

N


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P:

L

A ,

E

C:

P ( )

D FC

F C C H


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M

A168

1

P

2

H75

4

F/

3

D .

D18B20

5

D 6

232

D D

D/A

F

C

I

78

9

A D H I

1

2

4

3

5

6

7

8

9

F C C H


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F C C H


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1111

33332222

4444

55556666

F C C H

H

LENA M

M


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0

10

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50 60 70 80 90 100

rH Sollwe rt [%rH]

rHMesswert[%

rH]

Vaisala SHT75 Linear (SHT75)

%

%

F C C H


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weight

volume

Heat dissipation

Power consumption

Water cooling Air cooling

high

low

low

low

high

high

F C C C

P,FC> P,

P,FC< P,

C

: L


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Temperature control---Regulation algorithm

Adjustment

PWM_pump

Adjustment

temperatureFC,in

Adjustment

PWM_fan

Adjustment

temperatureFC,out

:2

+

-

+

+

TFC,in

TFC,out

TFC,middle

dTFC

+

-

- +

PWMfan

PWMpump

TFc,set

dTFC,set

eFC,L

eFC,P

I

P

P

I

u i , L

up , L

u i , L

u p , L

+

+ +

+

F C C C


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35=60

C, 210=60C, 4

F C C C


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