WO2009068187A1 - Fuel cell system - Google Patents

Fuel cell system Download PDF

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Publication number
WO2009068187A1
WO2009068187A1 PCT/EP2008/009588 EP2008009588W WO2009068187A1 WO 2009068187 A1 WO2009068187 A1 WO 2009068187A1 EP 2008009588 W EP2008009588 W EP 2008009588W WO 2009068187 A1 WO2009068187 A1 WO 2009068187A1
Authority
WO
WIPO (PCT)
Prior art keywords
fuel cell
humidifier
cell system
air
delivery means
Prior art date
Application number
PCT/EP2008/009588
Other languages
French (fr)
Inventor
Hans-Jörg Heidrich
Simon Hollnaicher
Gerald Hornburg
Jochen Sang
Original Assignee
Daimler Ag
Ford Global Technologies, Llc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Daimler Ag, Ford Global Technologies, Llc filed Critical Daimler Ag
Publication of WO2009068187A1 publication Critical patent/WO2009068187A1/en

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
    • H01M8/04089—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants
    • H01M8/04119—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants with simultaneous supply or evacuation of electrolyte; Humidifying or dehumidifying
    • H01M8/04126—Humidifying
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
    • H01M8/04089—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04223—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids during start-up or shut-down; Depolarisation or activation, e.g. purging; Means for short-circuiting defective fuel cells
    • H01M8/04268—Heating of fuel cells during the start-up of the fuel cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • the invention relates to a fuel cell system, in which an air delivery means comprises a first port to which a line is coupled which leads to a humidifier, a line leading from the humidifier to a first port of a fuel cell stack and a bypass line being provided which may be connected in such a way that air may be conveyed directly from the air delivery means to the fuel cell.
  • bypass line branches off from the line between the air delivery means (in particular a compressor) and the humidifier and leads back into the line between the humidifier and the fuel cell stack.
  • the bypass line serves to control the humidity of the air being conducted to the fuel cell stack.
  • the further a valve in the bypass line or to the bypass line is opened, the more air flows through the bypass line and the less air flows through the humidifier. Humidification of the air by the humidifier promotes good operation of the fuel cell stack.
  • the bypass line prevents the air stream from becoming too moist.
  • a valve leading to the bypass line may take the form of a gas limiter valve, regulating valve, throttle valve or directional control valve.
  • bypass line is co nnected (directly) to a further port of the air delivery means and/or (directly) to a further port of the fuel cell system.
  • the humidifier is a gas-to-gas humidifier, as known per se.
  • the air delivery means is a volumetric machine, preferably a compressor, or a continuous-flow machine, in particular a turbocompressor, which may in particular be electrically driven.
  • Fig. 1 is a schematic representation of the structure of a part of the prior art fuel cell system chosen to explain the invention
  • Fig. 2 is a schematic representation of a first variant according to the invention of the part of the fuel cell system shown in Fig. 1 ,
  • Fig. 3 is a schematic representation of a second variant according to the invention of the part of the fuel cell system shown in Fig. 1 and
  • Fig. 4 shows a third variant according to the invention of the part of the fuel cell system shown in Fig. 1.
  • air is fed to a fuel cell stack 10.
  • the air is compressed in a compressor 12, leaves the compressor 12 via a port 14 into the line 16, which leads to a humidifier 18, which humidifies the compressed air and conveys it via a line 20 to a port 22 of the fuel cell stack 10 and thus into the fuel cell stack 10.
  • a bypass line 26 branches off from the line 16 at a junction 24 as far as a junction 28 with the line 20.
  • a control valve 30 is arranged in the bypass line 26. The control valve 30 controls what proportion of the air compressed by the compressor 12 and passing out of the port 14 into the pipe 16 passes through the bypass line 26 and what proportion of the air passes through the humidifier 18.
  • junction 24 is dispensed with, and instead a second port 32 is provided at the compressor 12, to which the bypass line 26 is directly connected.
  • a second port 32 is provided at the compressor 12, to which the bypass line 26 is directly connected.
  • junction 28 is dispensed with, and a second port 34 is provided at the fuel cell stack 10, to which the bypass line 26 leads directly.
  • the two variants are combined, i.e. both junctions 24 and 28 are dispensed with in favor of the respective second ports 32 and 34.
  • junctions 24 and 28 are dispensed with in each embodiment, and indeed both in the embodiment according to Fig. 4, economies of installation space are achieved. It is less complex simply to provide a second port 32 in the compressor 12 or simply to provide a second port 34 at the fuel cell stack 34 than to introduce junctions 24 and 28.
  • a suitable valve may additionally be installed inside the compressor 12 and also inside the fuel cell stack 10, so that the air may exit as desired from one of the ports 14 and 32 of the compressor 12 or enter as desired into one of the ports 22 or 34 of the fuel cell stack. This makes it possible to operate the fuel cell stack with completely dry air, which may be advisable for example in the event of a cold start, since a proportion of air then no longer has necessarily to pass through the humidifier 18.
  • At least one heat exchanger with a further cooling medium is arranged in at least one of the lines 16 and/or 20, in order to adjust the temperature of the air compressed by the air delivery means 10 and simultaneously heated to a range tolerable for the components located downstream, such as humidifier 18 and fuel cell 10.
  • the heat exchanger may preferably take the form of a gas-to-gas heat exchanger, with the fuel cell outlet air as cooling medium.

Abstract

In fuel cell systems, air is compressed in an air delivery means (12) and fed via a humidifier (18) to a fuel cell stack (10). It is known in the prior art to branch a bypass line (26) off from the lines between compressor (12) and humidifier (18) or humidifier (18) and fuel cell stack (10), in order to convey a proportion of the air past the humidifier. According to the invention, the start point or the end point of the bypass line is moved to a second port (32) of the air delivery means (12) or a second port (34) of the fuel cell stack (10). In this way savings may be made with regard to junctions (24 or 28) in the line system, and it is also easier to incorporate valves.

Description

FUEL CELL SYSTEM
The invention relates to a fuel cell system, in which an air delivery means comprises a first port to which a line is coupled which leads to a humidifier, a line leading from the humidifier to a first port of a fuel cell stack and a bypass line being provided which may be connected in such a way that air may be conveyed directly from the air delivery means to the fuel cell.
Such a fuel cell system is known from DE 102 19 626 A1. The bypass line branches off from the line between the air delivery means (in particular a compressor) and the humidifier and leads back into the line between the humidifier and the fuel cell stack. The bypass line serves to control the humidity of the air being conducted to the fuel cell stack. The further a valve in the bypass line or to the bypass line is opened, the more air flows through the bypass line and the less air flows through the humidifier. Humidification of the air by the humidifier promotes good operation of the fuel cell stack. However, the bypass line prevents the air stream from becoming too moist. A valve leading to the bypass line may take the form of a gas limiter valve, regulating valve, throttle valve or directional control valve.
In particular in the case of a cold start, it is disadvantageous for the air in the fuel cell stack to be very moist, because the fuel cell stack has not as yet been sufficiently warmed up and water therein may condense and freeze. When switching off the fuel cell stack, as little moisture as possible should remain in the fuel cell stack. In these two situations as much air as possible is therefore passed through the bypass line. With many types of valve, a residual proportion of air always continues to pass through the humidifier, which is disadvantageous. If a complex directional control valve is used, the latter takes up a relatively large amount of space in the motor vehicle. The embodiment from DE 102 19 626 A1 is already disadvantageous because space is taken up by the junctions between the lines and the bypass line.
It is the object of the invention to provide a fuel cell system according to the preamble of claim 1 which avoids the above-stated disadvantages.
The object is achieved by a fuel cell system as claimed in patent claim 1. Thus, the bypass line is co nnected (directly) to a further port of the air delivery means and/or (directly) to a further port of the fuel cell system.
As a result of the invention, the previous branching of the line between air delivery means and humidifier and/or of the line between humidifier and fuel cell stack is dispensed with. In this way, space savings are achieved. The fuel cell system is markedly more compact than has previously been usual.
By moving the junction directly inside the air delivery means or the fuel cell stack, it is additionally possible to use a significantly more compact valve, in particular indeed a valve by means of which it is possible to switch over between the main line proper and the bypass line, in such a way that either solely the first port (allowing passage of air through the humidifier) or solely the respective further port (allowing passage of air through the bypass line past the humidifier) is opened. The same effect is achieved in the prior art only with a three-way valve, which takes up a very large amount of space. Such an arrangement is significantly easier to construct in the interior of the air delivery means or of the fuel cell stack. A simple example of incorporating valves into an air delivery means, namely a compressor, is explained for example in DE 101 04 606 A1.
It may also be advisable to provide a control valve in the bypass line, so that the proportion of air which passes through the bypass line may be adjusted continuously.
In a preferred application, the humidifier is a gas-to-gas humidifier, as known per se.
In a further preferred application, the air delivery means is a volumetric machine, preferably a compressor, or a continuous-flow machine, in particular a turbocompressor, which may in particular be electrically driven. Preferred embodiments of the invention are described below with reference to the drawings, in which
Fig. 1 is a schematic representation of the structure of a part of the prior art fuel cell system chosen to explain the invention,
Fig. 2 is a schematic representation of a first variant according to the invention of the part of the fuel cell system shown in Fig. 1 ,
Fig. 3 is a schematic representation of a second variant according to the invention of the part of the fuel cell system shown in Fig. 1 and
Fig. 4 shows a third variant according to the invention of the part of the fuel cell system shown in Fig. 1.
In a fuel cell system, air is fed to a fuel cell stack 10. The air is compressed in a compressor 12, leaves the compressor 12 via a port 14 into the line 16, which leads to a humidifier 18, which humidifies the compressed air and conveys it via a line 20 to a port 22 of the fuel cell stack 10 and thus into the fuel cell stack 10. In the prior art a bypass line 26 branches off from the line 16 at a junction 24 as far as a junction 28 with the line 20. A control valve 30 is arranged in the bypass line 26. The control valve 30 controls what proportion of the air compressed by the compressor 12 and passing out of the port 14 into the pipe 16 passes through the bypass line 26 and what proportion of the air passes through the humidifier 18. It is impossible in this case to prevent at least a small proportion of the air from always passing through the humidifier 18. If it is wished, when stopping operation of the fuel cell stack 10 or on cold starting of the fuel cell stack 10, to make the air particularly dry, this small proportion of air passing through the humidifier 18 is disadvantageous. If it were wished to provide special valves at the junctions 24 and 28, the structure would be particularly complex and a lot of space would be occupied. Even in the prior art embodiment shown in Fig. 1 , the junctions 24 and 28 occupy a lot of installation space in the motor vehicle in which the fuel cell system is designed to be operated.
The situation is improved by three different variants of the invention: In the first variant of the invention the junction 24 is dispensed with, and instead a second port 32 is provided at the compressor 12, to which the bypass line 26 is directly connected. In the embodiment according to Fig. 3 the compressor side remains unchanged, in particular the junction 24. Instead, junction 28 is dispensed with, and a second port 34 is provided at the fuel cell stack 10, to which the bypass line 26 leads directly. In the embodiment according to Fig. 4, the two variants are combined, i.e. both junctions 24 and 28 are dispensed with in favor of the respective second ports 32 and 34.
Because at least one of the junctions 24 and 28 is dispensed with in each embodiment, and indeed both in the embodiment according to Fig. 4, economies of installation space are achieved. It is less complex simply to provide a second port 32 in the compressor 12 or simply to provide a second port 34 at the fuel cell stack 34 than to introduce junctions 24 and 28.
A suitable valve may additionally be installed inside the compressor 12 and also inside the fuel cell stack 10, so that the air may exit as desired from one of the ports 14 and 32 of the compressor 12 or enter as desired into one of the ports 22 or 34 of the fuel cell stack. This makes it possible to operate the fuel cell stack with completely dry air, which may be advisable for example in the event of a cold start, since a proportion of air then no longer has necessarily to pass through the humidifier 18.
In a further preferred embodiment, at least one heat exchanger with a further cooling medium (not shown) is arranged in at least one of the lines 16 and/or 20, in order to adjust the temperature of the air compressed by the air delivery means 10 and simultaneously heated to a range tolerable for the components located downstream, such as humidifier 18 and fuel cell 10. The heat exchanger may preferably take the form of a gas-to-gas heat exchanger, with the fuel cell outlet air as cooling medium.
List of reference signs
10 Fuel cell stack
12 Compressor
14, 22,32,34 Port
16, 20 Line
18 Humidifier
24, 28 Junctions
26 Bypass line
30 Control valve

Claims

Patent Claims
1. A fuel cell system, in which an air delivery means (12) comprises a first port (14) to which a line (17) is coupled which leads to a humidifier (18), a line (20) leading from the humidifier (18) to a first port (22) of a fuel cell stack (10) and air being conveyable via a bypass line (26) optionally directly from the air delivery means (12) to the fuel cell (10), characterized in that the bypass line is connected to a further port (32) of the air delivery means (12) and/or to a further port (34) of the fuel cell stack (10).
2. The fuel cell system as claimed in claim 1 , characterized in that a valve is provided in the air delivery means (12) and/or in the fuel cell stack (10), which valve opens up solely the respective first or alternatively solely the respective further port.
3. The fuel cell system as claimed in claim 2, characterized by a control valve (30) in the bypass line (26).
4. The fuel cell system as claimed in one of the preceding claims, characterized in that the humidifier (18) is a gas-to-gas humidifier.
5. The fuel cell system as claimed in one of the preceding claims, characterized in that the air delivery means (12) is a volumetric machine, preferably a compressor.
6. The fuel cell system as claimed in one of claims 1 to 4, characterized in that the air delivery means (12) is a continuous-flow machine, preferably an electrically driven turbocompressor or turbocharger.
7. The fuel cell system as claimed in one of the preceding claims, characterized in that at least one heat exchanger with a further cooling medium is arranged in at least one of the lines (16) and/or (20).
8. The fuel cell system as claimed in claim 7, characterized in that the heat exchanger is a gas-to-gas heat exchanger.
9. The fuel cell system as claimed in claim 8, characterized in that the cooling medium for the gas-to-gas heat exchanger is the fuel cell outlet air.
PCT/EP2008/009588 2007-11-28 2008-11-13 Fuel cell system WO2009068187A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102007057191.9 2007-11-28
DE102007057191A DE102007057191A1 (en) 2007-11-28 2007-11-28 The fuel cell system

Publications (1)

Publication Number Publication Date
WO2009068187A1 true WO2009068187A1 (en) 2009-06-04

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Family Applications (1)

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PCT/EP2008/009588 WO2009068187A1 (en) 2007-11-28 2008-11-13 Fuel cell system

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WO (1) WO2009068187A1 (en)

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06132038A (en) * 1992-10-20 1994-05-13 Fuji Electric Co Ltd Solid highpolymer electrolyte type fuel cell
WO1997016648A1 (en) * 1995-11-02 1997-05-09 Aaf-Mcquay Incorporated Improvements in and relating to single screw compressors
US6106964A (en) * 1997-06-30 2000-08-22 Ballard Power Systems Inc. Solid polymer fuel cell system and method for humidifying and adjusting the temperature of a reactant stream
EP1463135A1 (en) * 2003-03-27 2004-09-29 Nissan Motor Co., Ltd. Fuel cell system
FR2861221A1 (en) * 2003-10-16 2005-04-22 Renault Sa Electricity generating system for motor vehicle, has compressor driven by turbine, where compressor and turbine form turbocompressor for internal combustion engine for supplying air to fuel cell system
US7160638B1 (en) * 1998-05-20 2007-01-09 Volkswagen Ag Fuel cell system and method for generating electrical energy using a fuel cell system
US20070092771A1 (en) * 2005-10-21 2007-04-26 Honda Motor Co., Ltd. Fuel cell system and scavenging method for use in a fuel cell system

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10104606A1 (en) 2001-02-02 2002-08-08 Daimler Chrysler Ag IC engine has compressor communicating with exhaust gas system via connecting line, flow is set by valve arrangement that can adopt one of three settings
US6884534B2 (en) 2001-05-03 2005-04-26 General Motors Corporation Electronic by-pass control of gas around the humidifier to the fuel cell stack

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06132038A (en) * 1992-10-20 1994-05-13 Fuji Electric Co Ltd Solid highpolymer electrolyte type fuel cell
WO1997016648A1 (en) * 1995-11-02 1997-05-09 Aaf-Mcquay Incorporated Improvements in and relating to single screw compressors
US6106964A (en) * 1997-06-30 2000-08-22 Ballard Power Systems Inc. Solid polymer fuel cell system and method for humidifying and adjusting the temperature of a reactant stream
US7160638B1 (en) * 1998-05-20 2007-01-09 Volkswagen Ag Fuel cell system and method for generating electrical energy using a fuel cell system
EP1463135A1 (en) * 2003-03-27 2004-09-29 Nissan Motor Co., Ltd. Fuel cell system
FR2861221A1 (en) * 2003-10-16 2005-04-22 Renault Sa Electricity generating system for motor vehicle, has compressor driven by turbine, where compressor and turbine form turbocompressor for internal combustion engine for supplying air to fuel cell system
US20070092771A1 (en) * 2005-10-21 2007-04-26 Honda Motor Co., Ltd. Fuel cell system and scavenging method for use in a fuel cell system

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