Fuel cell water transport

• US 4,973,530 A
• Filed: 12/21/1989
• Issued: 11/27/1990
• Est. Priority Date: 12/21/1989
• Status: Expired due to Fees

• Current Assignee: United States Department of Energy
• Original Assignee: United States Department of Energy
• Inventors: Hedstrom, James C., Vanderborgh, Nicholas E.
• Primary Examiner(s): Kalafut, Stephen J.
• Application Number:
  US07/454,608
• Time in Patent Office: 341 Days
• Field of Search: 429/13, 429/26, 429/30, 429/34
• US Class Current: 429/414
• CPC Class Codes: H01M 2300/0082 Organic polymers
• CPC Class Codes: H01M 8/04007 related to heat exchange
• CPC Class Codes: H01M 8/04119 with simultaneous supply or evacuation of electrolyte; Humidifying or dehumidifying
• CPC Class Codes: H01M 8/04291 Arrangements for managing water in solid electrolyte fuel cell systems H01M8/04119 takes precedence
• CPC Class Codes: H01M 8/1007 with both reactants being gaseous or vaporised H01M8/12 takes precedence
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

The moisture content and temperature of hydrogen and oxygen gases is regulated throughout traverse of the gases in a fuel cell incorporating a solid polymer membrane. At least one of the gases traverses a first flow field adjacent the solid polymer membrane, where chemical reactions occur to generate an electrical current. A second flow field is located sequential with the first flow field and incorporates a membrane for effective water transport. A control fluid is then circulated adjacent the second membrane on the face opposite the fuel cell gas wherein moisture is either transported from the control fluid to humidify a fuel gas, e.g., hydrogen, or to the control fluid to prevent excess water buildup in the oxidizer gas, e.g., oxygen. Evaporation of water into the control gas and the control gas temperature act to control the fuel cell gas temperatures throughout the traverse of the fuel cell by the gases.

Claims

1. A fuel cell using hydrogen gas as a fuel and oxygen gas as an oxidizer and a solid polymer membrane for proton transport therebetween, comprising:

a first flow field for transporting at least one of said hydrogen and oxygen gases adjacent said proton transport membrane for chemical reactions generating electrical current; and

a second flow field for receiving said at least one of said gases sequential with said first flow field and having a water transport membrane for regulating the humidity of said gas within said first flow field.

2. Apparatus according to claim 1, further including a gas flow channel repeatedly traversing said first and second flow fields, each traverse of said flow channel having a first channel length in said first flow field and a second channel length in said second flow field.

3. Apparatus according to claim 2, wherein said second channel length is effective to humidify said hydrogen gas for moisturizing said proton transport membrane effective to maintain ionic conductivity.

4. Apparatus according to claim 2, where said second channel length is effective to remove excess water from said oxygen gas.

5. Apparatus according to claim I, further including a fluid flow channel for maintaining a fluid flow adjacent said water transport membrane opposite said fuel cell gas effective to evaporate water from said water transport membrane for cooling said fuel cell gas.

6. A method for regulating the moisture content in a gas which chemically reacts adjacent a solid polymer membrane for proton transport in a fuel cell, comprising the steps of:

repeatedly traversing a flow of said gas through a series of flow channels, each flow channel having a first channel length for chemical reactions adjacent said proton transport membrane to generate a current in said fuel cell and a second channel length sequential with said first channel length and adjacent a water transport membrane for regulating the water content of said gas within said first channel length.

7. A method according to claim 6, wherein regulating said gas water content comprises the step of providing a fluid with excess water adjacent said water transport membrane opposite a flow of hydrogen fuel gas to humidify said hydrogen to maintain moisture in said proton transport membrane for ionic conductivity.

8. A method according to claim 6, wherein regulating said gas water content comprises the step of providing a relatively dry gas adjacent said water transport membrane opposite a flow of oxygen for water removal from said oxygen to said relatively dry gas.