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Aalborg Universitet
Development of a 400 W High Temperature PEM Fuel Cell Power Pack - Modelling and
System Control
Andreasen, Søren Juhl; Bang, Mads; Korsgaard, Anders; Nielsen, Mads Pagh; Kær, Søren
Knudsen
Publication date:
2006
Document Version
Accepted manuscript, peer reviewed version
Link to publication from Aalborg University
Citation for published version (APA):
Andreasen, S. J., Bang, M., Korsgaard, A., Nielsen, M. P., & Kær, S. K. (2006). Development of a 400 W High
Temperature PEM Fuel Cell Power Pack - Modelling and System Control. Poster session presented at Fuel Cell
Seminar 2006 Conference, Honolulu, Hawaii, United States.
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Development of a 400 W High Temperature PEM Fuel Cell Power Pack : Fuel Cell Stack Test
Søren Juhl Andreasen* , Mads Bang, Anders Korsgaard, Mads Pagh Nielsen, Søren Knudsen Kær
Institute of Energy Technology, Aalborg University, Pontoppidanstræde 101, 9220 Aalborg East, Denmark
Motivation
Fuel Cell Stack Test
The use of a liquid reformed hydrocarbon as fuel for fuel cells can reduce fuel storage volume considerably.
The PBI membrane technology used
in high temperature PEM (HTPEM)
fuel cells has great advantages when
using reformate fuel gas compared to
low temperature PEM fuel cells
(LTPEM).
A simple system has been designed consisting of a prototype 30 cell HTPEM fuel cell stack, a pressure reduction
valve and an axial blower. The stack is for initial tests supplied with pure hydrogen and is designed for cathode air
cooling, which simplifies the system significantly.
40
0.3
0.2
0.1
0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
HTPEM, | 150oC, Oair>10, AMEA =45.16cm2
”Simple and reliable
HTPEM fuel cell system
with cathode air cooling”
35
600
Stack Voltage [V]
30
500
25
400
20
300
15
200
10
Figure 3: System diagram of a simple HTPEM fuel cell system
for testing a 30 cell prototype stack.
The experiences obtained operating the system are, that the cathode air cooling efficiently cools the stack, but the
temperature profile of the stack changes with the airflow. Situations can occur at the inlet of the stack, where
temperatures are quite low at high airflows. This results in a fuel cell voltage drop, and hereby a power loss because of
the lower temperature.
Individual Cell Voltage Measurements, i=0,2A/cm2, O | 15
air
0.7
Figure 1: Simulation and measurements of a single HTPEM
fuel cell at different CO concentration levels.
100
5
Current Density [A/cm2]
Inlet cell voltage
”Temperature differences
introduce problems for
cathode air cooled stacks”
0.68
0
0
5
10
15
20
25
30
35
40
0
45
Current [A]
Figure 8: Polarization curve of 38 cell HTPEM fuel cell stack at
approximately 150oC.
The following conclusions were made while experimenting
with the stack, and loading it in different ways:
Intermediate cell voltages
End cell voltage
0.66
Cell Voltage [V]
The PBI membrane technology also
simplifies the PEM fuel cell system
de-sign greatly, which makes it an
ideal choice where reliable systems
are needed. A low air pressure loss
stack has been designed using
cathode air cooling.
700
Stack Electrical Power [W]
Fuel Cell Voltage [V]
0.4
The construction of the HTPEM fuel cell system illustrated in
figure 3, has resulted in a very simple and reliable HTPEM
fuel cell system.
38 Cell HTPEM Stack Polarization and Power Curve
o
HTPEM Fuel Cell Polarization at different CO concentrations, Tcell=180 C, O Air =2.5
1
1000ppm CO Measured
0.9
10000ppm CO Measured
20000ppm CO Measured
0.8
50000ppm CO Measured
1000ppm CO Simulated
0.7
10000ppm CO Simulated
20000ppm CO Simulated
0.6
50000ppm CO Simulated
0.5
Conclusions
• Very stable operation, stable fuel cell voltages, slowly
changing temperatures.
• Fast fuel cell dynamics, the fuel cells can quickly respond
to load steps.
• Long start-up time.
0.64
0.62
0.6
0.58
0.56
0.54
0.52
0.5
Figure 4: Stack temperatures at low load, 0.2 A/cm2. The front
of the stack is severely cooled by the incoming air.
2
5
10
15
20
25
29
Cell number [-]
Figure 5: Stack voltage differences measured in each cell. The
differences is primarily due to the temperature differences.
The design of the gas channels in the bipolar plates offer a very low pressure loss, which makes it possible to use small
Stack Air Flow Characteristics
low power consuming blowers for cathode air supply and cooling.
900
Figure 2: 30 cell HTPEM prototype stack designed at the
Institue of Energy Technology, at Aalborg University.
When using HTPEM fuel cells, no
membrane hydration problems occur,
and the CO tolerance is high. This
makes these types of fuel cells
preferable for reliable, robust fuel cell
systems running on reformate gas.
www.iet.aau.dk
”Low pressure loss
through stack makes it
possible to use small
blowers for air supply”
Stack Differential Pressure [Pa]
Fuel Cell Stack PQ line
800
m OAir=20
700
600
Figure 9: Picture of fuel cell stack in insulated box with axial
blower mounted on the outside.
500
400
300
m OAir=10
200
m OAir=5
100
0
0
=2
Air
mm
OAirO=1
50
100
150
200
250
Stack Air Flow [L/min]
Figure 7: Stack pressure-flow characteristics, with stoichiometries at a constant load of 0.5 A/cm^2.
The general experience of running the HTPEM fuel cell system was positive. he primary drawback being the temperature
gradient in the stack and a long start-up time because the system operates at 120oC-200oC to avoid liquid water. The first
of these problems has been dealt with in the 2nd generation HTPEM fuel cell stack design.
The conclusions and experiences made during these experiments, have given much knowledge for improvement of the
cathode air cooled HTPEM fuel cell stack design, and demonstrates the potential of using HTPEM fuel cells to make simple,
and reliable fuel cell systems. Furthermore, the experi-mental
results have given inputs to the further development and test of
different controllers and control strategies.
*[email protected]