WO2008105762A1 - Gas elimination for fuel cell - Google Patents

Gas elimination for fuel cell Download PDF

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Publication number
WO2008105762A1
WO2008105762A1 PCT/US2007/005087 US2007005087W WO2008105762A1 WO 2008105762 A1 WO2008105762 A1 WO 2008105762A1 US 2007005087 W US2007005087 W US 2007005087W WO 2008105762 A1 WO2008105762 A1 WO 2008105762A1
Authority
WO
WIPO (PCT)
Prior art keywords
coolant
pump
accumulator
fuel cell
gases
Prior art date
Application number
PCT/US2007/005087
Other languages
French (fr)
Inventor
Matthew P. Wilson
John D. Mcgrane
Original Assignee
Utc Power Corporation
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 Utc Power Corporation filed Critical Utc Power Corporation
Priority to PCT/US2007/005087 priority Critical patent/WO2008105762A1/en
Publication of WO2008105762A1 publication Critical patent/WO2008105762A1/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
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0267—Collectors; Separators, e.g. bipolar separators; Interconnectors having heating or cooling means, e.g. heaters or coolant flow channels
    • 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
    • H01M8/04007—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids related to heat exchange
    • H01M8/04029—Heat exchange using liquids
    • 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
    • H01M8/04007—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids related to heat exchange
    • H01M8/04044—Purification of heat exchange media
    • 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

  • This invention relates to a fuel cell and method for removing undesired gases from coolant within the fuel cell.
  • the fuel cell uses a cell stack assembly having porous water transport plates.
  • the fuel cell includes a coolant loop that creates a vacuum at a coolant inlet of the cell stack assembly.
  • a pump downstream from the cell stack assembly circulates coolant from the cell stack assembly to a heat exchanger, which deposits cooled coolant in an accumulator before returning the coolant to the cell stack assembly.
  • the vacuum requirement at the coolant inlet allows gas to be ingested into the coolant. This gas ingestion can cause the pump to fail and/or the heat rejection capability of the heat exchanger to be reduced.
  • a separator which is arranged between the cell stack assembly and the pump, provides its gases to a suction port of an eductor.
  • Some coolant from the pump is diverted to a motive inlet of the eductor, which picks up the gases from the separator to produce a flow of coolant entrained with the gases.
  • the flow is returned to the accumulator.
  • an undesired amount of ingested gas remains within the coolant and can interfere with the operation of the pump and heat exchanger. What is needed is a fuel cell and method that further reduces the ingested gases within the coolant prior to reaching the pump and/or heat exchanger.
  • a fuel cell includes a cell stack assembly.
  • a separator is adapted to separate coolant and gases received from the cell stack assembly.
  • a cooling loop includes at least one of a coolant pump and a heat exchanger for receiving coolant from the separator.
  • a gas removal loop includes an eductor having a motive inlet, a suction port and a diffuser. The suction port is in communication with the separator for receiving the gases.
  • a gas removal pump is in communication with the motive inlet for providing coolant to the motive inlet.
  • the diffuser is adapted to provide a flow of coolant entrained with the gases. The flow bypasses at least one of the coolant pump and the heat exchanger. In this manner, an additional pump is used in another loop to reduce the gases within the coolant prior to reaching the coolant pump and/or heat exchanger, thereby improving their operation.
  • a method of circulating coolant within the fuel cell includes circulating coolant between the cell stack assembly and an accumulator with a first pump, which is a high flow coolant pump in one example.
  • the accumulator includes fluid having coolant.
  • the method includes extracting gases from the coolant and producing a flow having coolant entrained with gases in the gas removal loop. The flow is returned to the accumulator.
  • the method further includes circulating the fluid, which includes the flow, from the accumulator to the eductor with a second pump to bypass the first pump.
  • the second pump is a low flow, self-priming pump in one example.
  • Figure 1 is a schematic view of an example fuel cell adapted to reduce the gases entrained in the coolant prior to reaching the coolant pump and/or heat exchanger within a coolant loop.
  • a fuel cell assembly 10 is shown in Figure 1.
  • a fuel cell 10 includes a cell stack assembly 12 having an anode 14 and cathode 16 separated by a proton exchange membrane 18, in the example shown.
  • the anode 14 receives fuel from a fuel source 20.
  • the cathode 16 receives air 22 supplied by a blower 24.
  • the cell stack assembly 12 includes porous water transport plates 26 used to remove product water and hydrate the anode and cathode 14, 16, as is known in the art.
  • a cooling loop 28 is provided for circulating coolant from the cell stack assembly 12 to a heat exchanger 34.
  • a coolant pump 32 pumps coolant from the cell stack assembly 12 to a separator 30 where the coolant, in one example water W, is separated from gases G.
  • the coolant pump 32 is a high-flow, low head rise pump used in cooling loops. Such pumps are adversely affected by gases, which can prevent the pump from priming.
  • the coolant is then pumped from the separator 30 to the heat exchanger 34 before being deposited into an accumulator 36.
  • the accumulator 36 contains water W, which acts as a reservoir to provide water to the cell stack assembly 12 to maintain balanced fuel cell operation throughout various operating conditions.
  • the accumulator 36 is filled with water W to a fill line F.
  • the coolant is returned from the accumulator 36 to a coolant inlet 42 of the cell stack assembly 12 through a coolant return line 38.
  • a pressure control device 40 is arranged between the accumulator 36 and cell stack assembly 12, in the example shown, to maintain a desired vacuum on the coolant inlet 42.
  • the vacuum at the coolant inlet 42 can contribute to an undesired level of gases within the coolant that can adversely affect the operation of the pump 32 and heat exchanger 34.
  • the fuel cell 10 includes a gas removal loop 44 indicated by double lines in the Figure.
  • the gas removal loop 44 reduces the amount of gases in the coolant prior to reaching the coolant pump 32 and heat exchanger 34 to improve their operation over prior art arrangements.
  • the gas removal loop 44 includes an eductor 48 having a suction port 50, a motive inlet 54, and a diffuser 56.
  • the eductor 48 operates in a known manner.
  • the gas removal loop 44 utilizes a low-flow, high head rise pump, which is not adversely affected by excessive gases within the coolant.
  • a gas removal pump 52 in one example, a self priming pump, provides coolant from the accumulator 36 to the motive inlet 54.
  • a gas line 46 provides the gases G from the separator 30 to the suction port 50.
  • the gases G which includes water vapor, provides a flow from the diffuser 56 that includes the coolant entrained with the gases G.
  • the flow is returned to the accumulator 36 through a water return line 58.
  • the gas removal loop 44 diverts a greater amount of gases G from the cooling loop 28 than prior art systems by bypassing the coolant pump 32 and heat exchanger 34.
  • the gases G can then be expelled from the fuel cell 10 through a vent 64 in the accumulator 36.
  • a demineralizer 60 is arranged between the gas removal pump 52 and the accumulator 36.
  • An orifice 62 is arranged between the gas removal pump 52 and the demineralizer 60. A portion of the flow from an outlet of the gas removal pump 52 is diverted to the demineralizer 60 prior to reaching the eductor 48.
  • the example fuel cell 10 for removing ingested gas from the. coolant is very small compared to prior art arrangements.
  • the gases are provided additional opportunity to be vented from the accumulator 36 by circulating a portion of the coolant in a separate gas removal loop 44, separate from the cooling loop 28. Further, there is very little increase in water volume, which is desirable to avoid freezing and thawing concerns.

Landscapes

  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Fuel Cell (AREA)

Abstract

A fuel cell is provided that includes a cell stack assembly. A separator is adapted to separate coolant and gases received from the cell stack assembly. A cooling loop includes at least one of a coolant pump and a heat exchanger for receiving coolant from the separator. A gas removal loop includes an eductor having a motive inlet, a suction port and a diffuser. The suction port is in communication with the separator for receiving the gases. A gas removal pump is in communication with the motive inlet for providing coolant to the motive inlet. The diffuser is adapted to provide a flow of coolant entrained with the gases. The flow bypasses at least one of the coolant pump and the heat exchanger. An additional pump is used in another loop to reduce the gases within the coolant prior to reaching the coolant pump and/or heat exchanger.

Description

GAS ELIMINATION FOR FUEL CELL
BACKGROUND QF THE INVENTION
This invention was made with government support with the Department of Energy under Contract No.: NAVC0302-AVP00201. The government therefore has certain rights in this invention.
This invention relates to a fuel cell and method for removing undesired gases from coolant within the fuel cell.
One type of fuel cell uses a cell stack assembly having porous water transport plates. The fuel cell includes a coolant loop that creates a vacuum at a coolant inlet of the cell stack assembly. A pump downstream from the cell stack assembly circulates coolant from the cell stack assembly to a heat exchanger, which deposits cooled coolant in an accumulator before returning the coolant to the cell stack assembly. The vacuum requirement at the coolant inlet allows gas to be ingested into the coolant. This gas ingestion can cause the pump to fail and/or the heat rejection capability of the heat exchanger to be reduced.
To minimize the impact of gas ingested into the coolant, a separator, which is arranged between the cell stack assembly and the pump, provides its gases to a suction port of an eductor. Some coolant from the pump is diverted to a motive inlet of the eductor, which picks up the gases from the separator to produce a flow of coolant entrained with the gases. The flow is returned to the accumulator. However, an undesired amount of ingested gas remains within the coolant and can interfere with the operation of the pump and heat exchanger. What is needed is a fuel cell and method that further reduces the ingested gases within the coolant prior to reaching the pump and/or heat exchanger.
SUMMARY OF THE INVENTION
A fuel cell is provided that includes a cell stack assembly. A separator is adapted to separate coolant and gases received from the cell stack assembly. A cooling loop includes at least one of a coolant pump and a heat exchanger for receiving coolant from the separator. A gas removal loop includes an eductor having a motive inlet, a suction port and a diffuser. The suction port is in communication with the separator for receiving the gases. A gas removal pump is in communication with the motive inlet for providing coolant to the motive inlet. The diffuser is adapted to provide a flow of coolant entrained with the gases. The flow bypasses at least one of the coolant pump and the heat exchanger. In this manner, an additional pump is used in another loop to reduce the gases within the coolant prior to reaching the coolant pump and/or heat exchanger, thereby improving their operation.
A method of circulating coolant within the fuel cell includes circulating coolant between the cell stack assembly and an accumulator with a first pump, which is a high flow coolant pump in one example. The accumulator includes fluid having coolant. The method includes extracting gases from the coolant and producing a flow having coolant entrained with gases in the gas removal loop. The flow is returned to the accumulator. The method further includes circulating the fluid, which includes the flow, from the accumulator to the eductor with a second pump to bypass the first pump. The second pump is a low flow, self-priming pump in one example. These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a schematic view of an example fuel cell adapted to reduce the gases entrained in the coolant prior to reaching the coolant pump and/or heat exchanger within a coolant loop. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
A fuel cell assembly 10 is shown in Figure 1. A fuel cell 10 includes a cell stack assembly 12 having an anode 14 and cathode 16 separated by a proton exchange membrane 18, in the example shown. The anode 14 receives fuel from a fuel source 20. The cathode 16 receives air 22 supplied by a blower 24. In one example, the cell stack assembly 12 includes porous water transport plates 26 used to remove product water and hydrate the anode and cathode 14, 16, as is known in the art.
A cooling loop 28 is provided for circulating coolant from the cell stack assembly 12 to a heat exchanger 34. A coolant pump 32 pumps coolant from the cell stack assembly 12 to a separator 30 where the coolant, in one example water W, is separated from gases G. In one example, the coolant pump 32 is a high-flow, low head rise pump used in cooling loops. Such pumps are adversely affected by gases, which can prevent the pump from priming. The coolant is then pumped from the separator 30 to the heat exchanger 34 before being deposited into an accumulator 36. The accumulator 36 contains water W, which acts as a reservoir to provide water to the cell stack assembly 12 to maintain balanced fuel cell operation throughout various operating conditions. The accumulator 36 is filled with water W to a fill line F. The coolant is returned from the accumulator 36 to a coolant inlet 42 of the cell stack assembly 12 through a coolant return line 38. A pressure control device 40 is arranged between the accumulator 36 and cell stack assembly 12, in the example shown, to maintain a desired vacuum on the coolant inlet 42. The vacuum at the coolant inlet 42 can contribute to an undesired level of gases within the coolant that can adversely affect the operation of the pump 32 and heat exchanger 34.
The fuel cell 10 includes a gas removal loop 44 indicated by double lines in the Figure. The gas removal loop 44 reduces the amount of gases in the coolant prior to reaching the coolant pump 32 and heat exchanger 34 to improve their operation over prior art arrangements. The gas removal loop 44 includes an eductor 48 having a suction port 50, a motive inlet 54, and a diffuser 56. The eductor 48 operates in a known manner.
The gas removal loop 44 utilizes a low-flow, high head rise pump, which is not adversely affected by excessive gases within the coolant. A gas removal pump 52, in one example, a self priming pump, provides coolant from the accumulator 36 to the motive inlet 54. A gas line 46 provides the gases G from the separator 30 to the suction port 50. The gases G, which includes water vapor, provides a flow from the diffuser 56 that includes the coolant entrained with the gases G. The flow is returned to the accumulator 36 through a water return line 58. The gas removal loop 44 diverts a greater amount of gases G from the cooling loop 28 than prior art systems by bypassing the coolant pump 32 and heat exchanger 34. The gases G can then be expelled from the fuel cell 10 through a vent 64 in the accumulator 36.
In one example, a demineralizer 60 is arranged between the gas removal pump 52 and the accumulator 36. An orifice 62 is arranged between the gas removal pump 52 and the demineralizer 60. A portion of the flow from an outlet of the gas removal pump 52 is diverted to the demineralizer 60 prior to reaching the eductor 48.
The example fuel cell 10 for removing ingested gas from the. coolant is very small compared to prior art arrangements. The gases are provided additional opportunity to be vented from the accumulator 36 by circulating a portion of the coolant in a separate gas removal loop 44, separate from the cooling loop 28. Further, there is very little increase in water volume, which is desirable to avoid freezing and thawing concerns. Although an example embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.

Claims

1. A fuel cell comprising: a cell stack assembly; a separator for separating coolant and gases received from the cell stack assembly; a cooling loop including at least one of a coolant pump and a heat exchanger for receiving the coolant from the separator; and a gas removal loop including an eductor, a gas removal pump in communication with the eductor for providing a flow of coolant entrained with the gases bypassing the at least one of the coolant pump and the heat exchanger.
2. The fuel cell according to claim 1, comprising an accumulator arranged between the cell stack assembly and the coolant pump, the accumulator adapted to receive coolant from the cooling loop and the flow from the gas removal loop.
3. The fuel cell according to claim 2, wherein the accumulator includes a vent for expelling the gases.
4. The fuel cell according to claim 2, comprising the heat exchanger arranged between the coolant pump and the accumulator.
5. The fuel cell according to claim 1, wherein the separator is arranged between the cell stack assembly and the coolant pump.
6. The fuel cell according to claim 1, wherein the eductor includes a motive inlet, a suction port and a diffuser, the suction port in communication with the separator for receiving the gases, the gas removal pump in communication with the motive inlet for providing coolant thereto, the diffuser for providing the flow.
7. The fuel cell according to claim 6, wherein the gas removal pump includes an outlet interconnected to the motive inlet.
8. The fuel cell according to claim 7, comprising a demineralizer interconnected to the outlet.
9. The fuel cell according to claim 2, wherein the gas removal pump draws coolant from the accumulator for circulation to the motive inlet before returning the coolant to the accumulator.
10. The fuel cell according to claim 9, wherein the gas removal loop includes a demineralizer.
11. The fuel cell according to claim 2, wherein the cooling loop bypasses the eductor, the coolant pump circulates coolant between the cell stack assembly, the heat exchanger, the separator and the accumulator.
12. The fuel cell according to claim 1, comprising a gas line interconnecting the cooling loop and the gas removal loop at the separator and suction port.
13. The fuel cell according to claim 1, wherein the cooling loop and the gas removal loop overlap at the accumulator.
14. A method of circulating coolant within a fuel cell comprising the steps of: circulating coolant between a cell stack assembly and an accumulator with a first pump, the accumulator having fluid including the coolant; extracting gases from the coolant with an eductor and producing a flow including coolant entrained with gases; returning the flow to the accumulator; and circulating the fluid, which includes the flow, from the accumulator to the eductor with a second pump, the flow bypassing the first pump.
15. The method according to claim 14, comprising the step of interconnecting the coolant loop and the gas removal loop by a gas line.
16. The method according to claim 14, comprising the step of interconnecting the cooling loop and the gas removal loop at the accumulator.
17. The method according to claim 14, comprising the step of reducing gases prior to reaching one of the heat exchanger and the coolant pump recirculating a portion of the flow from the accumulator to the eductor and back to the accumulator while bypassing the coolant pump with the gases.
18. The method according to claim 14, comprising the step of venting gases from the second pump prior to reaching the coolant pump.
19. The method according to claim 14, comprising the step of venting the gases from the second pump prior to reaching the heat exchanger.
PCT/US2007/005087 2007-02-26 2007-02-26 Gas elimination for fuel cell WO2008105762A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/US2007/005087 WO2008105762A1 (en) 2007-02-26 2007-02-26 Gas elimination for fuel cell

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US2007/005087 WO2008105762A1 (en) 2007-02-26 2007-02-26 Gas elimination for fuel cell

Publications (1)

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WO2008105762A1 true WO2008105762A1 (en) 2008-09-04

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PCT/US2007/005087 WO2008105762A1 (en) 2007-02-26 2007-02-26 Gas elimination for fuel cell

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6656622B2 (en) * 2000-11-15 2003-12-02 Utc Fuel Cells, Llc Degasified PEM fuel cell system

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6656622B2 (en) * 2000-11-15 2003-12-02 Utc Fuel Cells, Llc Degasified PEM fuel cell system

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