U.S. patent number RE40,060 [Application Number 11/050,625] was granted by the patent office on 2008-02-12 for fuel cell system.
This patent grant is currently assigned to NuCellSys GmbH. Invention is credited to Dietmar Mirsch, Bernd Scheiterlein.
United States Patent |
RE40,060 |
Mirsch , et al. |
February 12, 2008 |
Fuel cell system
Abstract
A fuel cell system comprises a fuel cell unit and facility for
humidifying process gases to provide a fuel for the fuel cell unit,
wherein water-carrying media conduits of the fuel cell unit are
provided at least in part as heatable media conduits.
Inventors: |
Mirsch; Dietmar
(Kirchheim-Nabern, DE), Scheiterlein; Bernd
(Crailsheim, DE) |
Assignee: |
NuCellSys GmbH
(Kirchheim/Teck-Nabern, DE)
|
Family
ID: |
7635573 |
Appl.
No.: |
11/050,625 |
Filed: |
February 4, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
09812890 |
Mar 21, 2001 |
06596425 |
Jul 22, 2003 |
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Foreign Application Priority Data
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Mar 21, 2000 [DE] |
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100 13 687 |
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Current U.S.
Class: |
429/414; 429/434;
429/442 |
Current CPC
Class: |
H01M
8/04119 (20130101); H01M 8/04156 (20130101); Y02E
60/50 (20130101) |
Current International
Class: |
H01M
8/04 (20060101) |
Field of
Search: |
;429/13,24,26 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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198 32 389 |
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Jul 1998 |
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DE |
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0 629 014 |
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Apr 1997 |
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EP |
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0 913 357 |
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May 1999 |
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EP |
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0 941 963 |
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Sep 1999 |
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EP |
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0 989 621 |
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Mar 2000 |
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EP |
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1 061 600 |
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Dec 2000 |
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EP |
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1 106 571 |
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Jun 2001 |
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EP |
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7326376 |
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Dec 1995 |
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JP |
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WO 93/19005 |
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Sep 1993 |
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WO |
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Primary Examiner: Crepeau; Jonathan
Attorney, Agent or Firm: Crowell & Moring LLP
Claims
What is claimed is:
.[.1. A fuel cell system comprising: a fuel cell unit; a humidifier
unit for humidifying process gases to be fed to the fuel cell unit;
and water-carrying media conduits which provide water to said
humidifier unit; wherein said water carrying media conduits include
a heating component arranged to heat at least a portion
thereof..].
2. The fuel cell system according to claim .[.1.].
.Iadd.12.Iaddend., further comprising a unit for extracting water
from process gases of said fuel cell unit and providing it to said
.[.media carrying conduits.]. .Iadd.at least one media
conduit.Iaddend..
3. The fuel cell system according to claim .[.1.].
.Iadd.12.Iaddend., wherein said heating component is electrically
powered and comprises at least a portion of said .Iadd.at least one
.Iaddend.media .[.conduits.]. .Iadd.conduit.Iaddend..
4. The fuel cell system according to claim .[.1.].
.Iadd.12.Iaddend., wherein the .Iadd.at least one .Iaddend.media
.[.conduits.]. .Iadd.conduit .Iaddend.including said heating
component .[.are.]. .Iadd.is .Iaddend.provided downstream of the
fuel cell unit.
5. The fuel cell system according to claim .[.1.].
.Iadd.12.Iaddend., wherein said .Iadd.at least one .Iaddend.media
.[.conduits.]. .Iadd.conduit .Iaddend.including said heating
component .[.are.]. .Iadd.is .Iaddend.disposed between a water
separator for separating water from cathode off-gas of said fuel
cell and a metering point for feeding media into a cathode air
input.
.[.6. The fuel cell system according to claim 1, further comprising
a drain line for discharging water from the fuel cell unit, said
drain line including a further heating component..].
7. A fuel cell system comprising: a fuel cell unit; a first conduit
for providing process air to a cathode side input of said fuel cell
unit; a humidifier unit disposed in said first conduit for adding
moisture to said process air; a second conduit for providing water
to said humidifier unit; wherein said second conduit comprises a
conduit section having a heating component for warming said
water.Iadd.; the fuel cell system further comprises at least one
temperature sensor; the heating component is activated to heat said
second conduit in dependence on a temperature monitored by said
temperature sensor; and the temperature sensor monitors ambient
temperature.Iaddend..
8. The fuel cell system according to claim 7, further comprising a
unit for extracting water from process gases of said fuel cell unit
and providing it to said second conduit.
9. The fuel cell system according to claim .[.1.].
.Iadd.12.Iaddend., wherein said heating component comprises a
heating sleeve surrounding at least a portion of said media
conduits.
10. The fuel cell system according to claim .[.1.].
.Iadd.12.Iaddend., wherein said heating component comprises a
heating element inside said media conduits.
.[.11. The fuel cell system according to claim 1, further
comprising at least one temperature sensor, wherein said heating
component is activated to heat said at least a portion of said
media conduits in dependence on a temperature monitored by said
sensor..].
12. .[.The.]. .Iadd.A .Iaddend.fuel cell system .[.according to
claim 11, wherein.]. .Iadd.comprising: a fuel cell unit; a
humidifier unit for humidifying process gases to be fed to the fuel
cell unit; and at least one water-carrying media conduit which
provides water to said humidifier unit; wherein, said at least one
water carrying media conduit includes a heating component arranged
to heat at least a portion thereof; the fuel cell system further
comprises at least one temperature sensor; the heating component is
activated to heat said at least a portion of said at least one
media conduit in dependence on a temperature monitored by said
sensor; and .Iaddend. .[.said.]. .Iadd.the .Iaddend.temperature
sensor monitors ambient temperature.
.[.13. The fuel cell system according to claim 11, wherein said
temperature sensor monitors temperature of a region of said fuel
cell system..].
.[.14. The fuel cell system according to claim 13, wherein said
temperature sensor monitors temperature in proximity to said water
carrying media conduits..].
.Iadd.15. Temperature regulation apparatus for a fuel cell system
having at least one fuel cell unit, said apparatus comprising: a
humidifier unit for humidifying process gases; heating means for
heating water fed to said humidifier, for humidifying said process
gases; and means for supplying heated humidified process gases from
said humidifier to said fuel cell unit; wherein, said heating means
heats said water as a function of ambient temperature for said fuel
cell system, as determined by a temperature sensor..Iaddend.
.Iadd.16. The apparatus according to claim 15, further comprising a
unit for extracting water from exhaust gases from said fuel cell
unit and providing it to said media conduit..Iaddend.
.Iadd.17. A method of operating a fuel cell system including at
least one fuel cell, said method comprising: providing a water
supply; humidifying a process gas stream by introducing water from
said water supply into said gas stream; feeding humidified process
gas from said gas stream to said fuel cell; and heating said water
from said water supply prior to introduction of said water into
said gas stream; wherein heating of said water in said heating step
is performed as a function of ambient temperature for said fuel
cell system, as determined by a temperature sensor..Iaddend.
.Iadd.18. The method according to claim 17, wherein said water
supply is provided by a water recovery unit which extracts water
from exhaust gases from said fuel cell unit..Iaddend.
.Iadd.19. The method according to claim 17, wherein said heating
step comprises heating at least a portion of a conduit which
supplies water from said water supply to said humidifier..Iaddend.
Description
BACKGROUND AND SUMMARY OF THE INVENTION
This application claims the priority of German patent document 100
13 687.7, filed Mar. 21, 2000, the disclosure of which is expressly
incorporated by reference herein.
The invention relates to a fuel cell system having a facility for
humidifying process gases to provide fuel for the fuel cell
itself.
To prevent the electrode membrane from drying out it is necessary
in fuel cells, particularly in those comprising proton-conducting
electrolyte membranes (PEM cells), to humidify the process gases
such as air or fuel gas. Water produced in the fuel cell, which is
customarily extracted from the fuel cell off-gas by means of a
water separator, can be used for this purpose, as disclosed, for
example in European patent document EP 0 629 014 B1.
Particularly in mobile fuel cell systems comprising
proton-conducting electrolyte membranes, high requirements are
placed on the control of water balance.
Accordingly, it is an object of the invention to provide a fuel
cell system with an improved supply of process water at low
temperatures.
This and other objects and advantages are achieved by the fuel cell
system according to the invention, in which heatable media conduits
are provided downstream of a fuel cell unit, which media conduits
are at least partially heatable. This structure has the advantages
that process water in the media conduits can be kept liquid
independently of ambient conditions, and that the risk of
blockages, due to freezing water, of media conduits and/or of
valves and pumps disposed in the media conduits is avoided.
Further advantages and refinements of the invention can be gathered
from the further claims and the description.
Other objects, advantages and novel features of the present
invention will become apparent from the following detailed
description of the invention when considered in conjunction with
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic depiction of a preferred arrangement
downstream of a water separator in a fuel cell system according to
the invention;
FIG. 2 is a further schematic depiction of a preferred arrangement
downstream of a water separator; and
FIG. 3 shows a further preferred arrangement of a fuel cell with
water removal.
DETAILED DESCRIPTION OF THE DRAWINGS
The invention is particularly suitable for fuel cell systems in
mobile installations. A particular problem with such installations
is that when the ambient temperature is below freezing, there is a
risk that water present in the system will freeze, and will block
conduits and valves and pumps. The installation cannot be started
up then, and the components may be damaged by the ice as it
forms.
According to the invention, media conduits are provided in the fuel
cell system which are heatable. Particularly preferably, media
conduits conveying liquid process water are at least partially
heatable, at least downstream of a fuel cell.
FIG. 1 depicts a first preferred embodiment of the invention.
Disposed in flow path 1 of cathode off-gas of a fuel cell unit (not
shown) is a water separator 2, which extracts at least part of the
water present in the cathode off-gas. Via a media conduit 3, the
process water is passed to a process air humidification system.
With the aid of a compressor 7, the process air is delivered, via
an air filter 5 and a conduit 6, to the cathode side of a fuel cell
unit (not shown). In the conduit 6, the process water from the
cathode off-gas is admixed to the process air.
The media conduit 3 is provided with a heatable conduit section 4,
or alternatively the entire media conduit 3 can be formed by the
heatable conduit section 4, which is preferably electrically
heatable. Beneficially, the heatable media conduit or the heatable
conduit section 4 is disposed between a water separator 2 for
separating water from cathode off-gas and a metering point for
feeding media into the cathode air.
Advantageously, the heatable conduit section 4 is supplied with
electrical power from a vehicle battery, (e.g., a 12 V battery), or
with electrical power from the fuel cell unit. It can also be
fitted with a control valve or a pump to adjust the amount of water
fed into the process air.
FIG. 2 depicts a further preferred embodiment of the invention,
which largely corresponds to that in FIG. 1, with identical
elements labeled with identical reference symbols. In the
illustrative embodiment shown, humidification in a two-stage
compressor is provided. Via an air filter 5, process air passes
into a conduit 6 and is compressed in a first compressor 8 and
passed on to a second turbo compressor 9. The process water is
introduced via the media conduit 3 or the heated conduit section 4
between the two compressors 8, 9 into the conduit 6.
At the metering point at which the process water is introduced into
the process air conduit 6, a fine nozzle for introducing the
process water is usually provided. The heated conduit section 4
advantageously ensures that no separate heating is required for
this nozzle. The use of heated process water prevents water from
freezing at the nozzle. This applies equally for any valves and/or
pumps for adjusting the amount of the process water which are
disposed in the media conduit 3.
FIG. 3 depicts a further preferred arrangement. A fuel cell unit 10
has an end plate 11 on which a first media feeder 12 for the anode
and a media offtake 14 for the anode gas, and a second media feeder
13 for the cathode and a second media outlet 15 for the cathode
off-gas are provided. (Details of how the media streams are
subdivided in the interior of the fuel cell unit 10 are not part of
the invention, and are not shown.) Also disposed on the end plate
11 are two water discharge lines 16, 17 which are provided to
remove water from the fuel cell unit 10. Beneficially, these water
removal lines 16, 17 are likewise provided with heatable conduit
sections 18, 19. The water removal lines discharge water which
collects in the anode or the cathode of the fuel cell unit 10,
preferably into a holding tank of a water separator.
Expediently, all media conduits which may carry liquid water
should, if possible, be provided with heatable conduit sections.
When running down the fuel cell system it is beneficial to ensure
that the water is flushed from the media conduits, so that as
little water as possible remains in the system. An advantage of the
invention is that even in the event of an emergency shutdown of the
fuel cell system, when removal of the water from the system is not
possible, the system can be started up again even at low external
temperatures at which the water remaining in the system is in the
form of ice.
The heatable conduits according to the invention can be made of
flexible or rigid material, and can be surrounded by a suitable
heating sleeve. Alternatively, they may have a suitable heating
element inside the conduit.
Expediently, temperature monitoring of the system is provided in
order to ensure that, in the event of the temperature dropping
below a critical value (e.g., below the freezing point), the
heatable media conduits are heated in the initial stage of starting
up the fuel cell system, so that frozen water in the media conduits
will be reliably liquefied. One option is to monitor the ambient
temperature; alternatively, temperature monitoring in the
respective temperature-critical regions of the fuel cell system,
especially in or near water-carrying media conduits, can be carried
out by one or more temperature sensors.
Another option is to provide for heating the heatable media
conduits from time to time in the event of prolonged standstill of
the system in a cold environment, if there is the threat of water
freezing, in order to maintain the temperature of water-carrying
media conduits essentially above the freezing point of water.
The foregoing disclosure has been set forth merely to illustrate
the invention and is not intended to be limiting. Since
modifications of the disclosed embodiments incorporating the spirit
and substance of the invention may occur to persons skilled in the
art, the invention should be construed to include everything within
the scope of the appended claims and equivalents thereof.
* * * * *