U.S. patent application number 11/825568 was filed with the patent office on 2007-11-22 for temperature zones in a solid oxide fuel cell auxiliary power unit.
This patent application is currently assigned to Delphi Technologies, Inc.. Invention is credited to Michael Thomas Faville, Malcolm James Grieve, Karl Jacob JR. Haltiner, Kevin Richard Keegan.
Application Number | 20070269694 11/825568 |
Document ID | / |
Family ID | 31999014 |
Filed Date | 2007-11-22 |
United States Patent
Application |
20070269694 |
Kind Code |
A1 |
Haltiner; Karl Jacob JR. ;
et al. |
November 22, 2007 |
Temperature zones in a solid oxide fuel cell auxiliary power
unit
Abstract
A method for fuel cell system thermal management includes:
maintaining a first zone at a first selected temperature range,
maintaining a second zone at a second selected temperature range,
and maintaining a third zone at a third selected temperature range.
The second zone is in thermal communication with a first sensor and
comprises a reformer, while the third zone is in thermal
communication with a second sensor and comprises a fuel cell stack.
The second selected temperature range is greater than the first
selected temperature range, while the third selected temperature
range is greater than the second selected temperature range. A
thermal management system for use with an auxiliary power unit
includes a first air control valve in fluid communication with a
process air supply and a fuel reformer zone, the first air control
valve in operable communication with a controller; a second air
control valve in fluid communication with a process air supply and
a hot zone, the second air control valve in electronic
communication with the controller; a reformer zone temperature
sensor in thermal communication with the fuel reformer and in
operable communication with the controller; a hot zone temperature
sensor in thermal communication with the hot zone and in operable
communication with the controller; a first outlet at the reformer
zone; and a second outlet at the hot zone.
Inventors: |
Haltiner; Karl Jacob JR.;
(Fairport, NY) ; Grieve; Malcolm James; (Fairport,
NY) ; Keegan; Kevin Richard; (Hilton, NY) ;
Faville; Michael Thomas; (Geneseo, NY) |
Correspondence
Address: |
DELPHI TECHNOLOGIES, INC.
M/C 480-410-202
PO BOX 5052
TROY
MI
48007
US
|
Assignee: |
Delphi Technologies, Inc.
|
Family ID: |
31999014 |
Appl. No.: |
11/825568 |
Filed: |
July 6, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11347140 |
Feb 3, 2006 |
7279243 |
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11825568 |
Jul 6, 2007 |
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09838356 |
Apr 19, 2001 |
7037613 |
|
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11347140 |
Feb 3, 2006 |
|
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60201568 |
May 1, 2000 |
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60268328 |
Feb 13, 2001 |
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Current U.S.
Class: |
48/197R ;
429/423; 429/442; 429/444; 429/495 |
Current CPC
Class: |
H01M 2250/20 20130101;
B60L 58/30 20190201; Y02T 90/34 20130101; H01M 8/04373 20130101;
Y02B 90/10 20130101; H01M 8/04708 20130101; H01M 8/04731 20130101;
B60L 58/33 20190201; H01M 2008/1293 20130101; Y02T 90/40 20130101;
Y02E 60/525 20130101; H01M 8/0612 20130101; H01M 8/04014 20130101;
Y02E 60/50 20130101; H01M 2250/10 20130101; H01M 8/04783 20130101;
H01M 8/2475 20130101; Y02B 90/14 20130101; Y02T 90/32 20130101;
Y02T 90/16 20130101 |
Class at
Publication: |
429/024 ;
429/013; 180/065.3 |
International
Class: |
H01M 8/04 20060101
H01M008/04; B60K 1/00 20060101 B60K001/00 |
Claims
1.-13. (canceled)
14. A method of controlling temperature at an auxiliary power unit
located in a vehicle comprising: sensing a reformer zone
temperature at a reformer zone; determining whether said reformer
zone temperature is at a first selected temperature range; adding a
process air flow to said reformer zone if said reformer zone
temperature rises above about said first selected temperature
range; sensing a hot zone temperature at a hot zone; determining
whether said hot zone temperature is in a second selected
temperature range; and adding a second process air flow to said hot
zone if said hot zone temperature rises above said second selected
temperature range.
15. The method in claim 14, further comprising reducing said
process air flow to said reformer zone if said reformer zone
temperature falls below said first selected temperature range.
16. The method in claim 14, further comprising increasing said
process air flow to said reformer zone if said reformer zone
temperature increases above said first selected temperature
range.
17. The method in claim 14, further comprising reducing said second
process air flow to said hot zone if said hot zone temperature
falls below said second selected temperature range.
18. The method in claim 14, further comprising increasing said
second process air flow to said hot zone if said hot zone
temperature increases above said second selected temperature
range.
19. The method in claim 14, wherein said adding said process air
flow comprises controlling said process air flow via a first air
control valve.
20. The method in claim 14, wherein adding said second process air
flow comprises controlling said second process flow air via a
second air control valve.
21. The method in claim 14, further comprising moving a reformer
air from said reformer zone to said hot zone.
22. The method in claim 14, further comprising moving a hot air to
a waste energy recovery unit.
23. The method in claim 14, wherein said first selected temperature
range is about 300.degree. C. to about 500.degree. C.
24. The method in claim 14, wherein said second selected
temperature range is about 600.degree. C. to about 800.degree.
C.
25. The method in claim 14, wherein said second selected
temperature range is about 725.degree. C. to about 775.degree.
C.
26-42. (canceled)
43. A method for fuel cell system thermal management, comprising:
maintaining a first zone at a first selected temperature range;
maintaining a second zone at a second selected temperature range,
wherein said second zone is in thermal communication with a first
sensor and comprises a reformer and wherein said second selected
temperature range is greater than said first selected temperature
range; and maintaining a third zone at a third selected temperature
range, wherein said third zone is in thermal communication with a
second sensor and comprises a fuel cell stack and wherein said
third selected temperature range is greater than said second
selected temperature range.
44. The thermal management system in claim 43, wherein said third
zone further comprises a waste energy recovery unit.
45. The thermal management system in claim 43, wherein said first
zone is in fluid communication with said second zone and said
second zone is in fluid communication with said third zone.
46. The thermal management system in claim 43, further comprising a
controller in operable communication with said first sensor and
said second sensor.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application claims the benefit of the dates of
earlier filed provisional applications, having U.S. Provisional
Application No. 60/201,568, filed on May 1, 2000, and U.S.
Provisional Application No. 60/268,328, filed on Feb. 13, 2001,
which are incorporated herein in their entirety.
BACKGROUND
[0002] Alternative transportation fuels have been represented as
enablers to reduce toxic emissions in comparison to those generated
by conventional fuels. At the same time, tighter emission standards
and significant innovation in catalyst formulations and engine
controls has led to dramatic improvements in the low emission
performance and robustness of gasoline and diesel engine systems.
This has reduced the environmental differential between optimized
conventional and alternative fuel vehicle systems. However, many
technical challenges remain to make the conventionally-fueled
internal combustion engine a nearly zero emission system having the
efficiency necessary to make the vehicle commercially viable.
[0003] Alternative fuels cover a wide spectrum of potential
environmental benefits, ranging from incremental toxic and carbon
dioxide (CO.sub.2) emission improvements (reformulated gasoline,
alcohols, etc.) to significant toxic and CO.sub.2 emission
improvements (natural gas, etc.). Hydrogen has the potential to be
a nearly emission free internal combustion engine fuel (including
CO.sub.2 if it comes from a non-fossil source).
[0004] The automotive industry has made very significant progress
in reducing automotive emissions. This has resulted in some added
cost and complexity of engine management systems, yet those costs
are offset by other advantages of computer controls: increased
power density, fuel efficiency, drivability, reliability and
real-time diagnostics.
[0005] Future initiatives to require zero emission vehicles appear
to be taking us into a new regulatory paradigm where asymptotically
smaller environmental benefits come at a very large incremental
cost. Yet, even an "ultra low emission" certified vehicle can emit
high emissions in limited extreme ambient and operating conditions
or with failed or degraded components.
[0006] One approach to addressing the issue of emissions is the
employment of fuel cells, particularly solid oxide fuel cells
(SOFC), in an automobile. A fuel cell is an energy conversion
device that generates electricity and heat by electrochemically
combining a gaseous fuel, such as hydrogen, carbon monoxide, or a
hydrocarbon, and an oxidant, such as air or oxygen, across an
ion-conducting electrolyte. The fuel cell converts chemical energy
into electrical energy. A fuel cell generally consists of two
electrodes positioned on opposite sides of an electrolyte. The
oxidant passes over the oxygen electrode (cathode) while the fuel
passes over the fuel electrode (anode), generating electricity,
water, and heat.
[0007] The fuel gas for the cell can be derived from conventional
liquid fuels, such as gasoline, diesel fuel, methanol, or ethanol.
The device, which converts the liquid fuel to a gaseous fuel
suitable for use in a fuel cell, is known as a reformer.
[0008] The long term successful operation of a fuel cell depends
primarily on maintaining structural and chemical stability of fuel
cell components during steady state conditions, as well as
transient operating conditions such as cold startups and emergency
shut downs. The support systems are required to store and control
the fuel, compress and control the oxidant and provide thermal
energy management.
SUMMARY
[0009] The above discussed and other drawbacks and deficiencies of
the prior art are overcome or alleviated by a thermal management
system. In an exemplary embodiment of the disclosure, a method of
controlling temperature at an auxiliary power unit located in a
vehicle includes: sensing a reformer zone temperature at a reformer
zone; determining whether the reformer temperature is at a first
selected temperature range; and adding a process air flow to the
reformer zone if the reformer zone temperature rises above the
selected temperature range.
[0010] In one embodiment, a method of producing electricity at a
fuel cell in a vehicle includes: adding a fuel and a reactant to a
fuel reformer; producing a reformate at the fuel reformer;
introducing the reformate to a fuel cell stack; and producing
electrical power at the fuel cell stack. A reformer zone
temperature is sensed at a reformer zone and it is determined
whether the reformer zone temperature is at a first selected
temperature range. If the reformer zone temperature rises above the
first selected temperature range a first process air is added to
the reformer zone.
[0011] One embodiment of a method for fuel cell system thermal
management, includes: maintaining a first zone at a first selected
temperature range, maintaining a second zone at a second selected
temperature range, and maintaining a third zone at a third selected
temperature range. The second zone is in thermal communication with
a first sensor and includes a reformer, while the third zone is in
thermal communication with a second sensor and includes a fuel cell
stack. The second selected temperature range is greater than the
first selected temperature range, while the third selected
temperature range is greater than the second selected temperature
range.
[0012] A thermal management system for use with an auxiliary power
unit includes a first air control valve in fluid communication with
a first process air supply and a fuel reformer zone, the first air
control valve in operable communication with a controller; a second
air control valve in fluid communication with a second process air
supply and a hot fuel cell zone, the second air control valve in
operable communication with the controller; a reformer zone
temperature sensor in thermal communication with the fuel reformer
and in operable communication with the controller; a hot zone
temperature sensor in thermal communication with the hot zone and
in electronic communication with the controller; a first outlet at
the reformer zone; and a second outlet at the hot zone.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Referring now to the drawing, which is meant to be exemplary
and not limiting:
[0014] FIG. 1 is a schematic of an exemplary fuel cell system with
a thermal management system.
DESCRIPTION OF A PREFERRED EMBODIMENT
[0015] Application of a SOFC in a transportation vehicle imposes
specific temperature, volume, and mass requirements, as well as
"real world" factors such as fuel infrastructure, government
regulations, and cost to be a successful product. This SOFC power
generation system focuses on the power output necessary to serve as
an auxiliary power unit on-board and not as the prime energy source
of the vehicle. This auxiliary power unit would be carried on-board
the vehicle as the electrical generator to supply the electrical
loads that are on-board the vehicle. The system operates at higher
overall efficiency (i.e., fuel energy input to electrical energy
output) than current electromechanical alternator systems in
current vehicles. The efficient operation of the SOFC system also
permits electrical power to be generated on-board a vehicle even
when the primary internal combustion engine is not operating (which
will be critical to "no-idle" emissions laws being enacted in
global regions).
[0016] Referring to FIG. 1, a fuel cell auxiliary power unit 10 is
schematically depicted. The auxiliary power unit 10 comprises a hot
zone 22, a reformer zone 24 and an outside zone 26. Hot zone 22,
which is an insulated enclosure, includes a fuel cell stack 28 and
may include a waste energy recovery unit 30 and a micro-reformer
31. Hot zone 22 may reach temperatures of about 600.degree. C. to
about 800.degree. C. once fuel cell stack 28 is operating at steady
state, preferably about 725.degree. C. to about 775.degree. C.
Reformer zone 24 is also an insulated enclosure and includes a fuel
reformer 32. Waste energy recovery unit 30 and micro-reformer 31
are shown in hot zone 22, however, they could also be located in
reformer zone 24. Reformer zone 24 may reach temperatures up to
about 500.degree. C. and optimally, should be about 300.degree. C.
to about 500.degree. C. once fuel reformer 32 is operating at
steady state. Outside zone 26 includes a process air supply 34, air
control valves 40 and 46, sensors (not shown), and controller 54
(e.g., an electronic controller). Outside zone 26 temperature is
less than about 120.degree. C.
[0017] Hot zone 22 is separated from reformer zone 24 by a thermal
wall 36 so that the operating temperature of reformer zone 24 can
be kept at a cooler temperature than the operating temperature of
hot zone 22. Additionally, outside zone 26 is separated from both
hot zone 22 and reformer zone 24 by a thermal wall 38 so that the
temperature of outside zone 26 can be kept at cooler temperatures
than the operating temperature of both hot zone 22 and reformer
zone 24.
[0018] Auxiliary power unit 10 operates by providing fuel reformer
32 with a fuel supply 56 and a process air flow 52, which is
generated from process air supply 34. Optionally, fuel supply 56 is
routed through micro-reformer 31 to fuel reformer 32. The process
of reforming hydrocarbon fuels, such as gasoline, is completed to
provide an immediate fuel source for rapid start up of fuel cell
stack 28, as well as protecting fuel cell stack 28 by removing
impurities. Fuel reforming can be used to convert a hydrocarbon
(such as gasoline) or an oxygenated fuel (such as methanol) into
hydrogen and byproducts (e.g., carbon monoxide, carbon dioxide, and
water). Common approaches include steam reforming, partial
oxidation, and dry reforming, and the like, as well as combinations
comprising at least one of the foregoing approaches.
[0019] Fuel reformer 32 produces a reformate 58, which can be
directed through a waste energy recovery unit 30 or directly to
fuel cell stack 28. Process air flow 52 can be provided through
waste energy recovery unit 30 to fuel cell stack 28. Fuel cell
stack 28 uses reformate 58 to create electrical energy 60 and waste
byproducts such as spent/unreacted fuel 62 and spent air 64.
Thermal energy from the flow of spent/unreacted fuel 62 and spent
air 64 can optionally be recovered in a waste energy recovery unit
30, which can recycle the flow of fuel and waste heat to the fuel
reformer and can also discharge a flow of reaction products 66
(e.g., water and carbon dioxide) from auxiliary power unit 10.
Waste energy recovery unit 30 converts unused chemical energy
(reformate 58) and thermal energy (exothermic reaction heat from
the fuel cell stack 28) to input thermal energy for fuel cell stack
28 through the use of an integration of catalytic combustion zones
and/or heat exchangers.
[0020] Ultimately, electrical energy 60 is harnessed from fuel cell
stack 28 for use by a motor vehicle (not shown). Fuel cell stack 28
produces a desired or predetermined amount of electrical power to
the vehicle. Fuel cell stack 28 can be a SOFC stack having a
multilayer ceramic/metal composite structure design to produce
electricity 60. It can comprise one or more multi-cell modules (not
shown), which produce a specific voltage that is a function of the
number of cells in the module.
[0021] The thermal management system provides process air flow 52
for the fuel cell stack 28 and fuel reformer 32, and can be used to
regulate the temperature in both hot zone 22 and reformer zone 24
of auxiliary power unit 10. The thermal management system includes
an air control valve 40 that is in fluid communication with an
inlet 42 of hot zone 22 via a pipe 44, tube, hose or other similar
device that can transport air and the like. Air control valve 40
supplies a process air flow 52 to hot zone 22. Process air flow 52
may be about ambient temperature or slightly above ambient
temperature. As process air flow 52 enters hot zone 22, a hot air
68 enters waste energy recovery unit 30. In the preferred
embodiment, hot air 68 may enter waste energy recovery unit 30 in
an area 70 that is separated from inlet 42. This allows process air
flow 52 to disperse through hot zone 22 before entering waste
energy recovery unit 30.
[0022] The thermal management system also includes an air control
valve 46 that is in fluid communication with an inlet 48 of
reformer zone 24 via a pipe 50, tube, hose or other similar device
that can transport air and the like. Air control valve 46 supplies
process air flow 52 to reformer zone 24. As process air flow 52
enters reformer zone 24, reformer air 72 enters hot zone 22 via a
pipe 74, hose, or other similar device that can transport air and
the like. There does not need to be a valve at pipe 74. Instead,
reformer air 72 moves from reformer zone 24 to hot zone 22 because
as process air flow 52 moves into reformer zone 24, reformer air 72
is then pushed out into hot zone 22. In addition, as process air
flow 52 enters reformer zone 24, the air pressure in reformer zone
24 may be slightly higher than the air pressure in hot zone 22, and
thus, reformer air 72 moves from reformer zone 24 to hot zone
22.
[0023] The thermal management system also includes a hot zone
temperature sensor 80 and a reformer zone temperature sensor 82.
Hot zone temperature sensor 80 is located in hot zone 22 and may be
located in an area away from fuel cell stack 28. It is preferable
that hot zone temperature sensor 80 not be located directly
adjacent fuel cell stack 28 because fuel cell stack 28 emits very
high temperatures. If hot zone temperature sensor 80 is located
directly adjacent to fuel cell stack 28, a false high reading may
occur. Reformer zone temperature sensor 82 is located in reformer
zone 24 and may be located in an area away from fuel reformer 32.
If reformer zone temperature sensor 82 is located directly adjacent
to fuel reformer 32, a false high reading may occur.
[0024] As explained above, hot zone 22 and reformer zone 24 are
insulated enclosures. In an exemplary embodiment, a microporous
insulation 84 is employed, which is a high efficiency insulation.
While a less efficient insulation may be utilized, it is preferred
to use an insulation that is efficient because of the very high
temperature and the limited amount of space that may be utilized
for the auxiliary power unit 10.
[0025] When auxiliary power unit 10 is energized and the system is
cold, e.g., about ambient temperature, various components of
auxiliary power unit 10 should be heated, preferably rapidly, to
bring auxiliary power unit 10 up to operating temperature. Once
auxiliary power unit 10 is operating, hot zone temperature sensor
80 and reformer zone temperature sensor 82 detect the temperature
in hot zone 22 and reformer zone 24, respectively.
[0026] If hot zone temperature sensor 80 detects that the
temperature in hot zone 22 increases above a desired temperature,
e.g., about 800.degree. C., temperature sensor 80, which is in
operable (e.g., electrical) communication with controller 54, sends
a signal to controller 54. Controller 54, which is in electrical
communication with air control valve 40, sends a signal to air
control valve 40 to open. When air control valve 40 opens, process
air flow 52 begins to flow through pipe 44 to inlet 42 and enters
hot zone 22. Process air flow 52 disperses through hot zone 22.
Process air flow 52 is cooler than the temperature in hot zone 22
and therefore, cools the temperature in hot zone 22.
[0027] Once the temperature in hot zone 22 begins to cool, process
air flow 52 is reduced or may even be stopped. By reducing process
air flow 52, the temperature in hot zone 22 begins to rise again
causing process air flow 52 to then increase. Process air flow 52
increases to cool the temperature in hot zone 22 and reduces to
increase the temperature in hot zone 22. As process air flow 52
enters hot zone 22, hot air 68 leaves hot zone 22 by entering waste
energy recovery 30 at area 70 or other suitable entry place. By
having hot air 68 exit hot zone 22, the pressure within hot zone 22
can be controlled.
[0028] In addition, if reformer zone temperature sensor 82 detects
that the temperature in reformer zone 24 is increasing above about
400.degree. C., reformer zone temperature sensor 82, which is also
in electrical communication with controller 54, sends a signal to
controller 54. Controller 54, which is electrical communication
with air control valve 46, sends a signal to air control valve 46
to open. When air control valve 46 opens, process air flow 52
begins to flow through pipe 50 to inlet 48 and enters reformer zone
24. Process air flow 52 disperses through reformer zone 22. Process
air flow 52 is cooler than the temperature in reformer zone 24 and
therefore, cools the temperature in reformer zone 24. Once the
temperature in reformer zone 24 begins to cool, process air flow 52
is reduced or may even be stopped. By reducing process air flow 52,
the temperature in reformer zone 24 begins to rise causing process
air flow 52 to then increase. Process air flow 52 increases to cool
the temperature in reformer zone 24 and reduces to increase the
temperature in reformer zone 24. As process air flow 52 enters
reformer zone 24, reformer air 72 leaves reformer zone 24 by
entering hot zone 22. By having reformer air 72 leave reformer zone
24, the pressure within reformer zone 24 can be controlled. In
addition, reformer air 72 is cooler than the temperature in hot
zone 22 and therefore, assists in cooling the temperature in hot
zone 22.
[0029] One advantage of the thermal management system is that the
temperature at hot zone 22 and reformer zone 24 can be regulated.
If hot zone 22 increases above about 800.degree. C., the fuel cell
stack would run too hot. If the temperature in hot zone 22 falls
below about 600.degree. C., fuel cell stack 28 would run too cold.
Thus, the thermal management system allows for increasing or
decreasing an amount of cooler air that enters hot zone 22 and also
allows for excess hot air 54 to enter waste energy recovery unit
30. In addition, it is desirable to maintain the operating
temperature of reformer zone 24 at about 300.degree. C. to about
500.degree. C. If the temperature in reformer zone 24 reaches
temperatures above about 500.degree. C., the shell of fuel reformer
32 may become too hot and fuel in fuel reformer 32 will combust or
coke before it reaches the reaction catalyst. If the shell becomes
too cold, the fuel will not be adequately vaporized and will not
react properly on the catalyst.
[0030] The thermal management system enables maintenance of
different temperatures in outside zone 26, reformer zone 24 and hot
zone 22. The temperature in reformer zone 24 is typically less than
the temperature in hot zone 22 and the temperature in outside zone
26 is typically less than the temperature in reformer zone 24. By
controlling these temperatures, the fuel cell system (which can
comprise any type of fuel cell stack) operates more efficiently.
Since controller 54 is typically physically disposed within outside
zone 26, it does not require high temperature compatibility.
[0031] While preferred embodiments have been shown and described,
various modifications and substitutions may be made thereto without
departing from the spirit and scope of the invention. Accordingly,
it is to be understood that the fuel reformer has been described by
way of illustration only, and such illustrations and embodiments as
have been disclosed herein are not to be construed as limiting to
the claims.
* * * * *