Power Control for a Polymer Electrolyte Membrane Fuel Cellmypages.iit.edu/~chmielewski/presentations/2005/AIChE... · 2012. 1. 27. · Power Control for a Polymer Electrolyte Membrane

Department of Chemical and Environmental Engineering

Illinois Institute of Technology

Power Control for a Polymer

Electrolyte Membrane Fuel Cell

Donald J. Chmielewski Kevin Lauzze

Department of Chemical

and Environmental Engineering

Illinois Institute of

Technology

Presented at the Annual Meeting of the AIChE: November 2005



Outline

PEMFC Model

• Mat. & Energy Balances and Electrochemistry

• Operating Characteristics

Controller Design

• Power Set-Point Tracking

• Temperature / Humidity Regulation

• Oxygen Regulation



What is a Fuel Cell?

Fuel Cell

H2

Electric Power

Air

H2O

Answer:

A device that

converts

fuel directly into

electrical power



Polymer Electrolyte Membrane

Fuel Cell (PEMFC)

N2

N2

N2

H2

H2

H2

H2

H2

H2

O2

O2

O2

H+

e- e-

Anode

Electrolyte

Cathode

O2 N2

N2

O2

O2

H+

H+

H+

H2O

H2O

H2O

H2O

H2O

H2O

Generated power due to

enthalpy released by

the reaction:

H2 + ½ O2 H2O

(H ~ 58 kcal/mole H2)



The Fuel Cell Stack Stack

Fuel

Flow

Air

Flow

Current

Flow



Dynamic Model of PEMFC

Cooling

Air In

Jacket

Exhaust

MEA

Anode

H2 In

Ecell

H2

Cathode

Air in

Cathode

Exhaust

O2

H2O

N2

Solid Material Current Collector

H+

H+

H+

H+

H+

H+

H+

H+

Insulator Parameters based

on 50 kW scale.

Pure hydrogen

feed

Air cooling is

assumed.



Material Balances in the Cathode

memOH

in

catcat

Ncat

in

N

in

cat

N

cat

memOHOcat

in

O

in

cat

O

cat

memOHOHcat

in

OH

in

cat

OH

cat

ArCFCF

CFCFdt

dCV

ArCFCFdt

dCV

ArCFCFdt

dCV

2

22

2

222

2

222

2

2

1

2

1



Energy Balances

memgensolambeff

soljacjacsolcatcatsol

solsolp

AQTTUA

TTUATTUAdt

dTVC

)(

)()(

Cathode Chamber Gas

Cooling Jacket Gas

Solid Material

)( catsol

catp

catcat

in

cat

in

catcat

cat TTC

UATFTF

dt

dTV

)( jacsol

jacp

jacjac

in

jac

in

jaccat

jac TTC

UATFTF

dt

dTV



Rates

F

jr OH

22

eOHOHfgen PrHQ 22

)( ,

Rate of Reaction: (production of water per area of membrane)

Heat Generation Rate: (per area of membrane)

celle EjP Power Generation: (electrical energy generation rate per area of membrane)



Current Density Depends on the Load

The fuel cell

looks like a

battery to the

electrical world.

Ecell

Eo

Rint

Load

DC

Fuel Cell I=j*Acell



Changing the Reaction Rate

Eload

Eo

-Rint

I

Eload

= Eo - R

int*I

Eload

= Rload

*I

Eload

Eo

Rint

DC

Battery I

Rload

F

/2 n

AIr mem

OH



Electrochemistry

mtohmactnercell EEEEE



Electrochemistry


OH

OHsoloner

P

PP

F

RTEE

2

22

2/1

ln2

Nernst Potential:



Electrochemistry


mem

memmemohm

A

tjAIRE

Ohmic Loss:

• ~ ionic conductivity of the membrane depends on humidification levels



Ohmic Resistance

)(2 TP

PxRH

satOH

xH2O = 0.35

humidity with increases

, ty,conductivi Ionic



Partial PEMFC Polarization Curve

0 2000




PEMFC Polarization Curve

0 2000




PEMFC Polarization Curve


)/(/ln

2

122

)( o

O

s

O

o

ooosol

act CCjjjjF

RTE

Activation Loss:

22

/ln22

1 )(

O

s

Osol

mt CCF

RTE

Mass Transfer Loss:



Surface Concentrations

222

)()2/1( O

s

OOH CCKr

Mass Transfer Rate :

/)1(1 RH

o eKK

Mass Transfer Coefficient :

(assuming O2 is the rate limiting species)

• ~ porosity coefficient



Flooding Resistance via the MTC

0 20 40 60 80 1000

0.5

1

1.5

2x 10

-3

Relative Humidity (%)

Mass

Tra

nsf

er

Co

eff

icie

nt



Efficient Operation

xw = 0.35

humidity with increases , ty,conductivi Ionic



Outline

PEMFC Model

• Mat. & Energy Balances and Electrochemistry

• Operating Characteristics

Controller Design

• Power Set-Point Tracking

• Temperature / Humidity Regulation

• Oxygen Regulation



Power Set-Point Tracking

Transportation Applications

PEMFCPower

Controller

Pe(sp) MV

Pe



Selecting the Power Output

0 200 400 600 800 10000

0.2

0.4

0.6

0.8

1

1.2

1.4

Current Density (mA/cm2)

Cel

l V

olt

age

(V)

0 200 400 600 800 10000

0.05

0.1

0.15

0.2

0.25

0.3

0.35

Po

wer

Den

sity

(w

atts

/cm

2)

E

eP

cell




0 200 400 600 800 10000

0.2

0.4

0.6

0.8

1

1.2

1.4


Cel

l V

olt

age

(V)

0 200 400 600 800 10000

0.05

0.1

0.15

0.2

0.25

0.3

0.35

Po

wer

Den

sity

(w

atts

/cm

2)

E

eP

cell




0 200 400 600 800 10000

0.2

0.4

0.6

0.8

1

1.2

1.4


Cel

l V

olt

age

(V)

0 200 400 600 800 10000

0.05

0.1

0.15

0.2

0.25

0.3

0.35

Po

wer

Den

sity

(w

atts

/cm

2)

E

eP

cell




0 200 400 600 800 10000

0.2

0.4

0.6

0.8

1

1.2

1.4


Cel

l V

olt

age

(V)

0 200 400 600 800 10000

0.05

0.1

0.15

0.2

0.25

0.3

0.35

Po

wer

Den

sity

(w

atts

/cm

2)

E

eP

cell



Power Controller

PEMFCE

cell

j

+- PI

j(sp)

Pe

PI

+

-

Pe(sp)



Power Controller

PEMFCE

cell

j

+- PI

j(sp)

Pe

PI

+

-

Pe(sp)

0 200 400 600 800 10000

0.2

0.4

0.6

0.8

1

1.2

1.4


Cel

l V

olt

age

(V)

0 200 400 600 800 10000

0.05

0.1

0.15

0.2

0.25

0.3

0.35

Po

wer

Den

sity

(w

atts

/cm

2)

E

eP

cell



Power Controller

PEMFCE

cell

j

+- PI

j(sp)

Pe

PI

+

-

Pe(sp)

Cooling

Air In

Jacket

Exhaust

MEA

Anode

H2 In

Ecell

H2

Cathode

Air in

Cathode

Exhaust

O2

H2O

N2


H+

H+

H+

H+

H+

H+

H+

H+

Insulator



Power Controller

0 5 10 15 20

0.17

0.18

0.19

Time (seconds)

Po

wer

Den

sity

(w

atts

/cm

2)

(sp) e

e P P



Power Controller

0 5 10 15 20 25

200

210

220

230

Time (seconds)

Cu

rren

t D

ensi

ty (

mA

/cm

2)

0 5 10 15 20 250.82

0.83

0.84

0.85

Time (seconds)

Cel

l V

olt

age

(V)

j

E cell



Power Controller

0 5 10 15 20 25

200

210

220

230

Time (seconds)

Cu

rren

t D

ensi

ty (

mA

/cm

2)

0 5 10 15 20 250.82

0.83

0.84

0.85

Time (seconds)

Cel

l V

olt

age

(V)

j

E cell

0 200 400 600 800 10000

0.2

0.4

0.6

0.8

1

1.2

1.4


Cel

l V

olt

age

(V)

0 200 400 600 800 10000

0.05

0.1

0.15

0.2

0.25

0.3

0.35

Po

wer

Den

sity

(w

atts

/cm

2)

E

eP

cell



Power Controller Flooding

0 5 10 15 20 2564

66

68

70

72

74

Time (seconds)

Tem

per

ature

(C

elsi

us)

0 5 10 15 20 2590

92

94

96

98

100

Rel

ativ

e H

um

idit

y (

%)

RH

cat T



Power Controller

0 5 10 15 20 25

0.18

0.19

0.2

0.21

0.22

Time (seconds)

Pow

er D

ensi

ty (

wat

ts/c

m2)

P e (sp) P e



Power Controller Failure

0 5 10 15 20 25200

300

400

Time (seconds)

Cu

rren

t D

ensi

ty (

mA

/cm

2)

0 5 10 15 20 250.5

0.6

0.7

0.8

Cel

l V

olt

age

(V)

j

cell E




0 200 400 600 800 10000

0.2

0.4

0.6

0.8

1

1.2

1.4


Cel

l V

olt

age

(V)

0 200 400 600 800 10000

0.05

0.1

0.15

0.2

0.25

0.3

0.35

Po

wer

Den

sity

(w

atts

/cm

2)

E

eP

cell



Power Controller

0 5 10 15 20 25

0.18

0.19

0.2

0.21

0.22

Time (seconds)

Pow

er D

ensi

ty (

wat

ts/c

m2)

P e (sp) P e




0 5 10 15 20 2570

80

90

100

Time (seconds)

Tem

per

atu

re (

Cel

siu

s)

0 5 10 15 20 2570

80

90

100

Rel

ativ

e H

um

idit

y (

%)

cat T

RH




0 200 400 600 800 10000

0.2

0.4

0.6

0.8

1

1.2

1.4


Cel

l V

olt

age

(V)

0 200 400 600 800 10000

0.05

0.1

0.15

0.2

0.25

0.3

0.35

Po

wer

Den

sity

(w

atts

/cm

2)

E

eP

cell



Temperature / RH Controller

PEMFC

Fjac

Tcat

+-

PIT

cat(sp)

Power

Controller

Pe(sp)

Ecell

Pe, j

RH

RH(sp)

+-

PI



PEMFC

Fjac

Tcat

+-

PIT

cat(sp)

Power

Controller

Pe(sp)

Ecell

Pe, j

RH

RH(sp)

+-

PI




PEMFC

Fjac

Tcat

+-

PIT

cat(sp)

Power

Controller

Pe(sp)

Ecell

Pe, j

RH

RH(sp)

+-

PI




PEMFC

Fjac

Tcat

+-

PIT

cat(sp)

Power

Controller

Pe(sp)

Ecell

Pe, j

RH

RH(sp)

+-

PI


Cooling

Air In

Jacket

Exhaust

MEA

Anode

H2 In

Ecell

H2

Cathode

Air in

Cathode

Exhaust

O2

H2O

N2


H+

H+

H+

H+

H+

H+

H+

H+

Insulator




0 20 40 60 800.18

0.2

0.22

0.24

0.26

0.28

0.3P

ow

er D

ensi

ty (

wat

ts/c

m2)

e P (sp)

e P

Time (seconds)




0 20 40 60 8065

70

75

80

85

Time (seconds)

Tem

per

atu

re (

Cel

siu

s)

0 20 40 60 8080

85

90

95

100

Rel

ativ

e H

um

idit

y (

%)

cat T

(sp)

cat T

RH



Oxygen Controller

PEMFC

Fjac

Tcat

RH(sp)

Power

Controller

Pe(sp)

Ecell

Pe, j

RH

ControllerRH,

+-

PIF

cat

xO2

xO2

(sp)



Oxygen Controller

PEMFC

Fjac

Tcat

RH(sp)

Power

Controller

Pe(sp)

Ecell

Pe, j

RH

ControllerRH,

+-

PIF

cat

xO2

xO2

(sp)



Oxygen Controller

PEMFC

Fjac

Tcat

RH(sp)

Power

Controller

Pe(sp)

Ecell

Pe, j

RH

ControllerRH,

+-

PIF

cat

xO2

xO2

(sp)

Cooling

Air In

Jacket

Exhaust

MEA

Anode

H2 In

Ecell

H2

Cathode

Air in

Cathode

Exhaust

O2

H2O

N2


H+

H+

H+

H+

H+

H+

H+

H+

Insulator



Oxygen Controller

0 100 200 300 4000

0.1

0.2

0.3

0.4

0.5

0.6

Time (seconds)

Po

wer

Den

sity

(w

atts

/cm

2)

P P

e

e

(sp)



Oxygen Controller

0 100 200 300 4000.05

0.1

0.15

0.2

0.25

Time (seconds)

Mo

le f

ract

ion o

f oxyg

en



Oxygen Controller

0 100 200 300 40040

50

60

70

80

90

100

Time (seconds)

Temperature (Celsius)

Relative Humidity (%)



Efficient Operation

eq

cell

E

E

Definition of Efficiency:

F

HE

OHf

eq2

2,

where

0 200 400 600 800 10000

0.2

0.4

0.6

0.8

1

1.2

1.4


Cel

l V

olt

age

(V)

0 200 400 600 800 10000

0.05

0.1

0.15

0.2

0.25

0.3

0.35

Po

wer

Den

sity

(w

atts

/cm

2)

E

eP

cell



Available Power and Efficiency

0.17 0.18 0.19 0.2 0.21 0.22

55

60

65

70

75

Power Density (watts/cm2)

Eff

icie

ncy

(%

)

Power Control

PEMFCE

cell

j

+- PI

j(sp)

Pe

PI

+

-

Pe(sp)




0 0.05 0.1 0.15 0.2 0.25 0.3

55

60

65

70

75


Eff

icie

ncy

(%

)

Power Control

Power & Humidity Control

PEMFC

Fjac

Tcat

+-

PIT

cat(sp)

Power

Controller

Pe(sp)

Ecell

Pe, j

RH

RH(sp)

+-

PI




0 0.1 0.2 0.3 0.4 0.5 0.6

55

60

65

70

75


Eff

icie

ncy

(%

)

Power Control

Power & Humidity Control

Power, Humidity & Oxygen Control PEMFC

Fjac

Tcat

RH(sp)

Power

Controller

Pe(sp)

Ecell

Pe, j

RH

ControllerRH,

+-

PIF

cat

xO2

xO2

(sp)



Acknowledgements

• Students:

Ayman Al-Qattan Yongyou Hu

Janet Ruettiger

• Collaborators:

Said Al-Hallaj J. Robert Selman

Vijay Ramani Satish Parulekar

Jai Prakash

• Funding:

Argonne National Laboratory

Graduate College, IIT

Armour College of Engineering, IIT

Department of Chemical & Environmental Engineering, IIT

Documents

Power Control for a Polymer Electrolyte Membrane Fuel Cellmypages.iit.edu/~chmielewski/presentations/2005/AIChE... · 2012. 1. 27. · Power Control for a Polymer Electrolyte Membrane