University of South Carolina FCR Laboratory Dept. of Chemical Engineering EXPERIMENT STUDIES

University of South Carolina

FCR Laboratory Dept. of Chemical Engineering

EXPERIMENT STUDIES





Gas (H 2

) out

Gas (H

2) i

n

Gas

(Air)

out

Gas (A

ir) in

End plate

Current collector

Gasket MEA Gasket

Gas diffusion layer

Graphite flow-channel block

Single PEM Fuel Cell Assembly





Catalyst (Pt)

e-

e-

e-

Hydrogen Air (Oxygen)

- +

-

Anode

2H+ + 2e-H2

Cathode

O2+ 4H+ + 4e- 2H2O

e-

e-

e-

e-

e-

H+

H+

H+

Membrane+

Schematic of fuel cell operation



Schematic of water transport in PEM fuel cell

Membrane

Catalyst (Pt)

H+ (H2O)n drag

H2O diffusion

Humidifier

Diffusion Layer

AirH2

H2O, H2 H2O, Air

e2H2H Pt2 OHe2O2/1H2 2

Pt2



50 100 150 200

Flow rate (cm3/min)

60

70

80

90

100R

ela

tive

hu

mid

ity (

%)

Humidification 70 oC



Anode

200 300 400 500

Flow rate (cm3/min)

80

82

84

86

88

90

92

94

96

98

100

Re

lativ

e h

um

idity

(%

)

Cathode




Anode & Cathode inlet humidity data



Dry gas

Humid gas

DI water

Schematic of the humidity chamber





PEM Fuel Cells Test station and data acquisition



Actual Serpentine Flow Field



3 way valve Hydrogen

Reformate

Mass Flow Controller

Heater

3 way valve

Bypass

Anode Gas In

Humidity Bottle

Mass Flow Controller

Heater

Bypass

Cathode Gas In

Humidity Bottle

Oxygen

Air

Thermocouple Controller

Heater

Cathode Gas Out

Anode Gas Out

PressureGauge

Back PressureRegulator



Fuel Cell

Cathode Vent

Anode Vent

Fuel Cell Test Station

Flow Diagram



Schematic of water collection set up

Ice bath

Balance

ThermocoupleThermocouple

Humidifier Fuel Cell Tester

BeakerBeaker

Vent

Balance

Fuel Cell

Vent



0 1 2 3 4 5 6 7 8 9 10

Current (A)

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Cel

l vol

tage

(V

)

T(A/C)=85/75 oC

T(A/C)=95/85 oC

Polarization curves for PEM fuel cell.( Tcell = 70 oC, pressure(A/C) = 2/2 atm, Low stoic.)



0 10 20 30 40 50 60

Time (hour)

0

2

4

6

8

10

12

Cur

rent

(A

)

TA/C = 85/75 oC

TA/C = 75/65 oC

TA/C = 65/55 oC

TA/C = 95/85 oC

Humidity effects on PEM fuel cell performance (70 oC cell temperature, P(A/C): 2/2 atm, flow rate (A/C): 76/319 cm3/min



0 10 20 30 40

Time (hr)

0

2

4

6

8

10

12

Cu

rre

nt

(A)

Tcell = 55 oC

Tcell = 75 oC

Tcell = 65 oC

Cell temperature effects on the performance at 0.6 V( T(A/C) = 75 oC/Bypass, pressure(A/C) = 1/1 atm, flow rate(A/C) = 66/277 cm3/min)



Cell Temp.(oC)

Current density (A/cm2)

Anode Water Balance (g/hr)

Cathode Water Balance (g/hr) Overall

Water inat

75oC

Water out

Max. water out

at Cell Temp.

Cross to

Cathode

Water inw/o Hum.

Generation Water out

Max. water out

at Cell

Temp.

Cross from Anode

% errorcross-over

water

55 0.47 1.18 0.67 0.38 0.51 0.00 1.56 2.01 2.69 0.45 13

65 0.59 1.18 0.42 0.54 0.76 0.00 1.97 2.68 4.73 0.71 7.7

75 0.31* 1.18 0.31 1.58 0.87 0.00 1.04* 1.90 9.15 0.86 2.2

Water balance in PEM fuel Cell



T(A/C) (oC)

TCell

(oC)


Flux of water

(g/s-cm2)

Mole H2O

/Moles H+

75/Bypass 55 0.47 1.44*10-5 0.16

75/Bypass 65 0.59 2.14*10-5 0.19

75/Bypass 75 0.31* 2.44*10-5 0.43*

Flux of water







End plate

Current collector

Gasket

MEA

Gasket

Gas diffusion layer (E-Lat)

Graphite flow-channel block

Pressure sensitive film

Bolt holes

Bolts

Schematic of PEM fuel cell with the pressure sensitive film



Gasket Type Diffusion Layer Film Type Torque (in-lbf/bolt)

100 125 150

Incompressible (7 mils)

TORAY (8 mils) Super Low 234 psi 261 psi 302 psi

CARBEL-TORAY

(11 mils)

Low 1065 psi 1247 psi 1270 psi

E-LAT

(20 mils)

Low 1214 psi 1349 psi > 1400 psi

Pressure inside fuel cell as measured by pressure sensitive film.(1 psi = 1 lbf/in

2, 1 mil = 2.54 x10-5 m)



0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4


0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0C

ell

volta

ge

(V

)

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

Po

we

r d

en

sity

(W

/cm

2)

100 in-lb/bolt

100 in-lb/bolt

125 in-lb/bolt

125 in-lb/bolt

150 in-lb/bolt

150 in-lb/bolt

Effect of torque on the cell polarization & power density with an E-LAT (Tcell = 70 oC, T(A/C) = 85/75 oC, P(A/C) = 15/15 psig)



0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1


0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0C

ell

volta

ge

(V

)

-0.1

-0.0

0.1

0.2

0.3

0.4

0.5

Po

we

r d

en

sity

(W

/cm

2)

100 in-lb/bolt

100 in-lb/bolt

125 in-lb/bolt

125 in-lb/bolt

150 in-lb/bolt

150 in-lb/bolt

Effect of torque on the cell polarization & power density with TORAYTM & CARBEL

(Tcell = 70 oC, T(A/C) = 85/75 oC, P(A/C) = 15/15 psig)



0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2


0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0C

ell

volta

ge

(V)

0.0

0.1

0.2

0.3

0.4

0.5

Po

we

r de

nsi

ty (

W/c

m2)

100 in-lb/bolt

100 in-lb/bolt

125 in-lb/bolt

125 in-lb/bolt150 in-lb/bolt

150 in-lb/bolt

Effect of torque on the cell polarization & power density with a TORAYTM

(Tcell = 70 oC, T(A/C) = 85/75 oC, P(A/C) = 15/15 psig)



0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4


-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

Po

we

r d

en

sity

(W

/cm

2)

E-lat

Carbel100-TorayToray

Comparison of power densities for three diffusion layers at torque 125 in-lbf/bolt







0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4


0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Ce

ll vo

ltag

e (

V)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

Po

we

r d

en

sity

(W

/cm

2)

308 psi

T(A/C) = 75/65 oC

802 psi

T(A/C)=65/55 oC

572 psi

T(A/C) = 75/65 oC

572 psi

T(A/C) = 75/65 oC

308 psi

T(A/C) = 75/65 oC

802 psi

T(A/C)=95/85 oC

802 psi

T(A/C)=95/85 oC

802 psi

T(A/C)=65/55 oC

Effect of humidity & compression pressure on the cell polarization & power density at Tcell = 50 oC



0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2


0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0C

ell v

olta

ge (

V)

T(A/C)=75/65 oC

T(A/C)=65/55 oC

T(A/C)=85/75 oC

T(A/C)=95/85 oC

Effect of humidity on the cell polarization forTcell = 50 oC and compression pressure 308 psi.



Example water collection data for the anode side(Tcell = 50 oC, T(A/C) = 75/65 oC & compression pressure = 802 psi )



Hum.temp.

(oC)


Anode water balance (g/min)

Cathode water balance (g/min) Overall

accum. (g/min)

Water in

Water out

Accum. at

anode

Maximum water out at cell temp.

Water in

Gen. Water out

Accum. at

cathode


65/55 0.89 0.0124

0.0208

-0.0084 0.0017 0.0379 0.0499 0.0773 0.0106 0.0324 0.0022

75/65 0.86 0.0227

0.0324

-0.0097 0.0017 0.0682 0.0483 0.0986 0.0179 0.0314 0.0081

85/75 0.78 0.0472

0.0573

-0.0101 0.0017 0.1152 0.0439 0.1402 0.0189 0.0294 0.0088

95/85 0.75* 0.1198

0.1674

-0.0475 0.0015 0.2474 0.0419 0.2412 0.0481 0.0275 0.0005

Water balance in PEM fuel cell(Cell voltage 0.5 V, cell temp. 50 oC, compression pressure 802 psi)

(*Performance degrading at 95/85 oC requires data to be estimated using an average current).



Hum.temp.

(oC)


Anode water balance (g/min)

Cathode water balance (g/min) Overall

accum. (g/min)

Water in

Water out

Accum. at

anode


Water in

Gen. Water out

Accum. at

cathode


65/55 0.87 0.0119

0.0283

-0.0164 0.0015 0.0361 0.0486 0.0568 0.0279 0.0310 0.0115

75/65 0.89 0.0223

0.0394

-0.0171 0.0014 0.0674 0.0497 0.0750 0.0422 0.0309 0.0251

85/75 0.85 0.0504

0.0602

-0.0098 0.0016 0.1242 0.0477 0.1133 0.0586 0.0310 0.0488

95/85 0.82* 0.1329

0.1765

-0.0436 0.0016 0.2743 0.0461 0.2116 0.1088 0.0303 0.0651

Water balance in PEM fuel cell(Cell voltage 0.5 V, cell temp. 50 oC, compression pressure 308 psi)

(*Performance degrading at 95/85 oC requires data to be estimated using an average current).





-

-+

+





Schematic of Air Bleed System

H2 /CO/H2O (in)

H2 /CO2 /H2O (out) O2 /H2O (out)

O/H2O (in)

Check valve

Filter

Flow meter

Air



0 200 400 600 800 1000 1200 1400 1600 1800

Current density (mA/cm2)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0C

ell

volta

ge

(V

)

CARBEL CL

w/o air bleed CARBEL CL

air bleed (5 %)

CARBEL CL

Neat H2

Single Side ELAT

Neat H2

Single Side ELAT

w/o air bleedSingle Side ELAT

air bleed (5 %)

Performance comparison between CARBEL CLTM and Single Side ELATTM GDM for 500 ppm CO.



Performance comparison between CARBEL CLTM and Single Side ELATTM GDM for 3000 ppm CO.

0 200 400 600 800 1000 1200 1400 1600 1800


0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0C

ell

volta

ge

(V

)

CARBEL CL

w/o air bleed CARBEL CL

air bleed (15 %)

CARBEL CL

Neat H2

SSE

Neat H2

SSE

w/o air bleed

SSE

air bleed (15 %)



101 102 103 1042 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3 4 5 6 7 8


0.0

0.1

0.2

0.3

0.4

0.5

An

od

e O

verv

olta

ge

(E

H2 -

EH

2/C

O)

(dashed lines) 3000 ppm CO/H2; (solid lines) 500 ppm CO/H2;

(■) SSE w/ air bleed; (□) SSE w/o air bleed; (●) CARBEL CL w/ air bleed; (○) CARBEL CL w/o air bleed.

Anode overpotentials (calculated by difference) due to CO poisoning for CARBEL CLTM and Single Side ELATTM GDM at different conditions



0 1 2 3 4 5 6 7 8

Time (hr)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8C

ell v

olta

ge (

V)

Neat H2 Neat H2

500 ppm CO/H2 for 5 min.

BaseBase

-0.323

(V/min)

Base Base

0.056

-0.332 -0.417 -0.400 -0.417 -0.400

0.051 0.053 0.053 0.0560.059

Base Base50 ppm CO/H2 (Base)

Transient performance with 50 and 500 ppm CO at 600 mA/cm2 with CARBEL CL GDM.



0 1 2 3 4 5 6 7 8

Time (hr)

0.4

0.5

0.6

0.7

0.8

0.9C

ell v

olta

ge (

V)

Neat H2 Neat H2


BaseBase Base BaseBase Base50 ppm CO/H2 (Base) Base


Air bleeding (5%)

Transient performance with 50 and 500 ppm CO at 600 mA/cm2 during air-bleed with CARBEL CL GDM.



0 1 2 3 4 5

Time (hr)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8C

ell

volta

ge

(V

)

Neat H2 (Base) Neat H2 (Base)

3000 ppm CO/H2 for 5 min.3000 ppm CO/H2 for 5 min.

0.088

(V/min)

- 0.971

(V/min)

0.092 0.099 0.096 0.094 0.098

-1.410 -1.437-1.437-1.413 -1.437

Base Base Base Base Base

Transient performance with neat hydrogen and 3000 ppm CO at 600 mA/cm2 with CARBEL CL GDM.



0 1 2 3 4 5

Time (hr)

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Ce

ll vo

ltag

e (

V)

Neat H2 Neat H2


-0.115

(V/min)

0.341

-0.134 -0.128 -0.125 -0.134 -0.127

0.323 0.357 0.323 0.3340.358


Neat H2 Neat H2 Neat H2 Neat H2 Neat H2

Air bleeding (15 %)

Transient performance with neat hydrogen and 3000 ppm CO at 600 mA/cm2 during air-bleed withCARBEL CL GDM.



0 1 2 3 4 5 6

Time (hr)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8C

ell v

olta

ge (

V)

Neat H2 Neat H2

3000 ppm CO/H2 for 5 min.3000 ppm CO/H2 for 5 min.

-0.729

(V/min)

0.075

-0.738 -0.746 -0.742 -0.752 -0.796

0.069 0.0670.0760.073 0.070

Base50 ppm CO/H2 (Base) Base Base Base Base Base

Transient performance with 50 and 3000 ppm CO at 600 mA/cm2 with Single-Sided ELAT GDM.



0 1 2 3 4 5 6 7 8

Time (hr)

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Ce

ll vo

ltag

e (

V)

Neat H2 Neat H2

3000 ppm CO/H2

for 5 min.

-0.109

(V/min)

Base

0.186

-0.173 -0.174-0.171 -0.168 -0.179

0.196 0.1920.180 0.1810.188

50 ppm CO/H2 (Base) Base Base BaseBase 50 ppm CO/H2 (Base)

Air bleeding (15 %)

3000 ppm CO/H2

for 5 min.

Transient performance with 50 and 3000 ppm CO at 600 mA/cm2 during air-bleed with Single-Sided ELAT GDM.



-Humidification Effect: The results show how the current changed with inlet humidity & cell temperature

-Clamp Torque Effect: Optimal compression pressure obtained. This optimum was explained in terms of changes in the porosity & conductivity.

-Interaction between compression pressure & humidity: The performance at the higher compression pressure is sensitive with changing humidity condition. Water balance data show the water transports during the fuel cell operation.

-CO poisoning on the catalyst: The results show the CO effect on the performance of PEM Fuel cell.

-The experiment data provided in useful to verify mathematical model and their prediction for PEM Fuel cell performance.



Documents

University of South Carolina FCR Laboratory Dept. of Chemical Engineering EXPERIMENT STUDIES