摘要:
A fuel cell assembly within an electrochemical fuel cell stack has an anode layer and a cathode layer. A cooling layer is disposed adjacent the fuel cell assembly. Each layer comprises channels for directing a fluid stream from an inlet to a an outlet. The coolant stream channels extend such that, in operation, the coolest region of the cooling layer coincides with the region of the cathode layer having the highest concentration of oxygen (and/or the lowest water content), and the warmest region of the cooling layer coincides with the region of the cathode layer having the lowest concentration of oxygen (and/or the highest water content). The fuel stream channels extend such that, in operation, the fuel stream is directed to a region of the anode layer which coincides with the region of the cathode layer in which the oxidant stream has the lowest concentration of oxygen (and/or the highest water content) and is subsequently directed to a region of the anode layer which coincides with the region of the cathode layer in which the oxidant stream has the highest concentration of oxygen (and/or the lowest water content).
摘要:
A fuel cell assembly within an electrochemical fuel cell stack has a cooling jacket disposed adjacent the cathode layer. The cooling layer comprises a coolant stream inlet, a coolant stream outlet, and at least one channel for directing a coolant stream from the coolant stream inlet to the coolant stream outlet. The coolant stream channels extend such that the coolest region of the cooling layer substantially coincides with the region of the adjacent cathode layer having the highest concentration of oxygen (and also the lowest water content), and the warmest region of the cooling layer substantially coincides with the region of the adjacent cathode layer having the lowest concentration of oxygen (and also the highest water content).
摘要:
An electrochemical fuel cell assembly includes a membrane electrode assembly which comprises an anode, a cathode having a surface thereof exposed to ambient air, and an ion exchange membrane interposed between the anode and the cathode. A seal forms a gas-impermeable barrier around the anode to which a gaseous fuel stream is supplied. The assembly further includes a thermally conductive plate having a plurality of thermally conductive members or fins extending from a major surface of the plate. The thermally conductive members contact portions of the exposed cathode surface. Adjacent thermally conductive members cooperate with the plate and the exposed cathode surface to form air conducting channels. Heat generated exothermically in the membrane electrode assembly is dissipated to the atmosphere through the thermally conductive members.
摘要:
An electrochemical fuel cell stack has a first end plate, a second end plate, and fuel cell assemblies interposed therebetween. Each fuel cell assembly includes a membrane electrode assembly having at least one manifold header opening formed in the assembly for directing at least one of a fluid fuel stream, a fluid oxidant stream and a fluid coolant stream through the assembly. A tie rod extends within the opening and through each of the first and second end plates. Fastening means are disposed at opposite ends of the tie rod. Compressive means are interposed between at least one of the fastening means and at least one of the first and second end plates. In operation, the fastening means and the compressive means urge the first end plate toward the second end plate, thereby applying compressive force to the fuel cell assemblies.
摘要:
An embossed fluid flow field plate for electrochemical cells comprises two sheets of compressible, electrically conductive material. Each sheet has two oppositely facing major surfaces. At least one of the major surfaces has an embossed surface which has a fluid inlet formed therein. The embossed surface has at least one open-faced channel embossed therein extending from the fluid inlet for conducting pressurized fluid introduced at the fluid inlet. A metal sheet is interposed between each of the compressible sheets. The compressible, electrically conductive sheet preferably comprises graphite foil.
摘要:
A method and apparatus selectively oxidizes, within the fuel cell assembly, the carbon monoxide present in a fuel stream fed to the assembly. A quantity of catalyst is contained within at least a portion of a fuel stream passageway within the stack. The carbon monoxide is selectively oxidized by the catalyst to carbon dioxide, and carbon monoxide produced by the reverse water-shift reaction is also oxidized.
摘要:
A method and apparatus is provided for removing water accumulated at the cathode of an electrochemical fuel cell incorporating a solid polymer ion exchange membrane. Liquid water accumulated at the cathode can be removed by maintaining a partial pressure of water vapor in the hydrogen-containing gas supply below the saturation pressure of water vapor therein such that water accumulated at the cathode is drawn by a concentration gradient toward the anode across the membrane and is absorbed as water vapor into the hydrogen-containing gas supply between the inlet and the outlet. In one embodiment, the partial pressure of water vapor in the hydrogen-containing gas supply is maintained below the saturation pressure of water vapor therein by imparting a pressure drop between the inlet and the outlet sufficient to draw water accumulated at the cathode toward the anode. In another embodiment, the partial pressure of water vapor at the inlet of the hydrogen-containing gas supply is maintained at less than the saturation pressure of water vapor therein. Liquid water accumulated at the cathode can also be removed by maintaining a partial pressure of water vapor in the oxygen-containing gas supply below the saturation pressure of water vapor therein such that water accumulated at the cathode is drawn by a concentration gradient and is absorbed as water vapor into the oxygen-containing gas supply between the inlet and the outlet. Liquid water accumulated at the cathode can also be removed by absorbing water vapor into both the hydrogen-containing gas supply and the oxygen-containing gas supply.
摘要:
A laminated fluid flow field assembly for an electrochemical fuel cell comprises a separator layer and a stencil layer. The separator layer is formed of electrically conductive, substantially fluid impermeable sheet material. The stencil layer is formed of electrically conductive sheet material, and has a fluid inlet and at least one opening extending between its major surfaces and in fluid communication with the fluid inlet. The separator layer and the stencil layer are consolidated along one of their major surfaces. In operation, the separator layer and the stencil layer cooperate to form an open-faced channel for conducting pressurized fluid introduced at the fluid inlet.
摘要:
An electrochemical fuel cell is provided for converting a fuel reactant stream and an oxidant reactant stream to a reaction product stream and electrical energy. The fuel cell includes a membrane electrode assembly interposed between two separator layers. The separator layers are formed of thin electrically conductive sheet material which is substantially impermeable to the fuel and oxidant reactant streams. The membrane electrode assembly comprises first and second electrode layers formed of porous electrically conductive sheet material. The electrode layers have a catalyst associated therewith, and an ion exchange membrane is interposed between the first and second electrode layers. The electrode layers include passages, such as the interstitial spaces within the electrode material or grooves formed in the surface of the electrode material, for flowing a reactant stream between an inlet and outlet within the electrode layer. The incorporation of the reactant flow passages within the electrode material permits the use of thin, lightweight separator layers, thus providing higher power-to-volume and power-to-weight ratios than conventional fuel cells having reactant flow passages engraved, milled or molded in the separator plates.
摘要:
An embossed fluid flow field plate for electrochemical cells comprises two sheets of compressible, electrically conductive material. Each sheet has two oppositely facing major surfaces. At least one of the major surfaces has an embossed surface which has a fluid inlet formed therein. The embossed surface has at least one open-faced channel embossed therein extending from the fluid inlet for conducting pressurized fluid introduced at the fluid inlet. A metal sheet is interposed between each of the compressible sheets. The compressible, electrically conductive sheet preferably comprises graphite foil. A method of fabricating an embossed separator plate for use in conjunction with an electrochemical fuel cell comprises (1) providing two sheets of compressible, electrically conductive sheet material, (2) interposing a metal sheet between each of the compressible sheets, and (3) embossing an open-faced channel in at least one of the surfaces of the sheets facing away from the metal sheet.