Start up of proton exchange membrane fuel cell

• US 6,127,056 A
• Filed: 10/09/1998
• Issued: 10/03/2000
• Est. Priority Date: 10/09/1998
• Status: Expired due to Fees

• Current Assignee: International Fuel Cells LLC (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: International Fuel Cells LLC (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Bonville, Leonard J., Wheeler, Douglas J.
• Primary Examiner(s): KALAFUT, STEPHEN J
• Application Number:
  US09/169,405
• Time in Patent Office: 725 Days
• Field of Search: 429/13, 429/26, 429/32, 429/38
• US Class Current: 429/429
• CPC Class Codes: H01M 2300/0082 Organic polymers
• CPC Class Codes: H01M 8/0258 characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant
• CPC Class Codes: H01M 8/04007 related to heat exchange
• CPC Class Codes: H01M 8/04022 Heating by combustion
• CPC Class Codes: H01M 8/04223 during start-up or shut-down; Depolarisation or activation, e.g. purging; Means for short-circuiting defective fuel cells
• CPC Class Codes: H01M 8/04225 during start-up
• CPC Class Codes: H01M 8/04302 applied during start-up
• CPC Class Codes: H01M 8/241 with solid or matrix-supported electrolytes
• CPC Class Codes: H01M 8/2457 with both reactants being gaseous or vaporised
• CPC Class Codes: H01M 8/2483 characterised by internal manifolds
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

A proton exchange membrane fuel cell has a noble metal or noble metal alloy catalyst 15 disposed in its air inlet manifold 13. During start up, a fuel cell is warmed to operating temperature by introducing a small amount of hydrogen into a flow of air to the air inlet 12 of the fuel cell where they react with the catalyst to produce heat at subflame temperatures. The adiabatic temperature rise of the gas stream is limited to about 150° F. by limiting the hydrogen to about one volume percent of the fuel/oxidant mixture, thereby to be capable of raising the fuel cell temperature, for instance, from -40° C. (-40° F.) to about +45° C. (+113° F.), without flame, explosion or drying out of the membrane.

Claims

1. In a fuel cell having a proton exchange membrane electrolyte and process oxidant channel, fed through an oxidant inlet manifold, in which oxidant is transported to the cathode side of the fuel cell, a method of warming the fuel cell during start up of operation, comprising:

supporting a metal or metal alloy catalyst in said manifold; and

providing a dilute mixture of hydrogen and oxidant to said oxidant inlet manifold at start up, said mixture having a volume percent of hydrogen less than 4%.

2. A method according to claim 1 further comprising:

monitoring the concentration of hydrogen in the mixture and adjusting the concentration to provide an adiabatic temperature rise of the gas stream about +85°

C. (+150°

F.).

3. A method according to claim 1 wherein said mixture is monitored and controlled to maintain about 1% hydrogen by volume.

4. A method according to claim 1 wherein said supporting step comprises:

supporting a noble metal or noble metal alloy catalyst in said manifold.

5. A fuel cell comprising:

a proton exchange membrane electrolyte;

a process oxidant channel for delivery of process oxygen to the cathode side of said fuel cell, said channel including an oxidant inlet manifold;

a supported metal or metal alloy catalyst disposed in said oxidant inlet manifold;

a source of hydrogen;

a source of oxygen;

means operative upon start up of said fuel cell to flow a stream of oxidant from said source of oxidant to said process oxidant channel; and

means operative upon start up of said fuel cell to introduce hydrogen from said source of hydrogen into said oxidant stream, thereby to provide a dilute hydrogen/oxidant mixture, having less than four volume percent of hydrogen, to said supported catalyst, whereby the reaction thereof on said supported catalyst will warm said gas and in turn warm said fuel cell.

6. Apparatus according to claim 5 further comprising means for adjusting the concentration of hydrogen in said dilute hydrogen/oxidant mixture to about one volume percent of the hydrogen/oxidant mixture so as to provide an adiabatic temperature rise of the gas stream of about +85°

C. (+150°

F.).

7. Apparatus according to claim 5 wherein

said catalyst is a noble metal or a noble metal alloy.