The invention pertains to an electrochemical cell, and in particular to an electrochemical cell comprising a manifold with positionable ports.
In general, a fuel cell is an electrochemical device that can convent energy stored in fuels such as hydrogen, methanol and the like, into electricity without combustion of the fuel. A fuel cell generally comprises a negative electrode, a positive electrode, and a separator within an appropriate container. Fuel cells operate by utilizing chemical reactions that occur at each electrode. In general, electrons are generated at one electrode and flow through an external circuit to the other electrode to balance the chemical reactions. This flow of electrons creates an over-voltage between the two electrodes that can be used to drive useful work in the external circuit. In commercial embodiments, several “fuel cells” are usually arranged in series, or stacked, in order to create larger over-potentials.
A fuel cell is similar to a battery in that both generally have a positive electrode, a negative electrode and electrolytes. However, a fuel cell is different from a battery in the sense that the fuel in a fuel cell can be replaced without disassembling the cell to keep the cell operating. Additionally, fuel cells have several advantages over other sources of power that make them attractive alternatives to traditional energy sources. Specifically, fuel cells are environmentally friendly, efficient and utilize convenient fuel sources, for example, hydrogen or methanol.
As noted above, the fuel in a fuel cell can be replaced without disassembling the cell. Generally, the fuel in a fuel cell is a fluid such as, for example, hydrogen gas, which is pumped or circulated to the anode, while an oxidizing agent, such as air (oxygen), is delivered to the cathode. Additionally, reaction products are generally removed from the system. The delivery of appropriate reactants to the anode and the cathode, as well as the removal of reaction products, introduce specific fluid flow issues.
Fuel cells have potential uses in a number of commercial applications and industries. For example, fuel cells are being developed that can provide sufficient power to meet the energy demands of a single family home. In addition, prototype cars have been developed that run off of energy derived from fuel cells. Furthermore, fuel cells can be used to power portable electronic devices such as computers, phones, video projection equipment and the like. Fuel cell systems are generally described in U.S. Pat. No. 6,565,998, entitled “Direct methanol fuel cell system with a device for the separation of the methanol and water mixture,” U.S. Pat. No. 6,544,677, entitled “Fuel cell system,” and U.S. Pat. No. 6,475,655, entitled “Fuel cell system with hydrogen gas separation,” all of which are hereby incorporated by reference herein.
In a first embodiment, the invention pertains to an electrochemical cell comprising an anode, a cathode and an electrolyte in contact with the anode and the cathode. In these embodiments, the electrochemical cell can further comprise a flow network comprising a manifold frame having at least one manifold port, the manifold port comprising a port body with a bore that forms a channel through the port body wherein the manifold port can move in at least one dimension relative to the manifold frame.
In a second embodiment, the invention pertains to an electrochemical cell comprising an anode, a cathode and an electrolyte in contact with the anode and the cathode. In these embodiments, the electrochemical cell can further comprise a flow network comprising a manifold structure having a manifold frame and at least one manifold port, the manifold port comprising a port body with a bore that forms an opening through the port body and a protrusion that extends outwardly from the port body, the protrusion engaging a groove on the manifold frame wherein the manifold port can move relative to the manifold frame when the manifold is disengaged from the electrochemical cell.
In a third embodiment, the invention relates to an electrochemical cell comprising an anode, a cathode, and an electrolyte in contact with the anode and the cathode. In these embodiments, the electrochemical cell can further comprise a flow network comprising a manifold frame having a manifold port connected to a flow tube, wherein the flow tube is composed of a composite comprising a polymer and a conductive additive. In some embodiments, the composite can comprise PVDF and carbon powders and/or carbon fibers.
In another aspect, the invention pertains to an electrochemical cell comprising an anode, a cathode and an electrolyte in contact with the anode and the cathode. In these embodiments, the electrochemical cell can further comprise a manifold frame having a manifold port, the manifold port comprising a port body with a bore that forms a channel through the manifold port and a baffle located within the bore to provide a more uniform fluid flow through the opening of the port relative to corresponding flow through an equivalent bore without the baffle.
In a further aspect, the invention pertains to a method of assembling a fuel cell comprising adjusting a manifold port on a manifold structure to engage a corresponding port in fluid communication with a fuel cell stack, wherein the manifold port and the corresponding port define a fluid flow path when engaged, and wherein the manifold port is adjusted by moving the manifold port relative to a manifold frame that supports other manifold elements.
In another embodiment, the invention pertains to a vehicle comprising an electrochemical cell stack and at least one manifold as described herein operably connected to the electrochemical cell stack.
The present invention includes in one embodiment at least one floating port. The floating port design allows for an easily effected plug-in connection between fuel cell components, such as a fuel cell stack and a manifold. This means of connection greatly reduces the number of fasteners required, as compared to the prior art face seal connection. Further, this means of connection greatly reduces the positional tolerance requirements of the ports as compared to the prior art radial seal joints.
The present invention further includes in one embodiment at least one fluid diffuser or baffle disposed in a port. Such baffle (diffuser) acts to provide an even dispersion of fluid to a cell stack through the relatively large oval port. Fluid is typically supplied by a round hose to the port, concentrating the fluid flow toward the center of the port and providing diminished flow at both edges of the port. The baffle provides for even fluid flow across the full-length dimension of the port.
The present invention includes in one embodiment, at least one over molded port connection. The outer body of the port is preferably formed of a metal, preferably stainless steel. The inner portion of the port, that portion in contact with the fluid being transported, is then formed of a material that is impervious to the fluid, preferably a plastic material such as PVDF. The plastic material is preferably injection molded around portions of the metallic body. All surfaces that contact the fluid media are then formed of impervious plastic material, while the metallic body provides the structural strength to withstand a known burst pressure (typically, 414 kpa). Further, the metallic frame may be formed with integral mounting pins for effecting the mating of fuel cell components.
The present invention is a manifold for a fuel cell, including at least one floating manifold port disposable in an oversized opening defined in a manifold frame, the manifold port being shiftable in at least one plane relative to the oversized opening for reducing the positional tolerance requirement of the manifold port, thereby effecting enhanced mating of adjacent fuel cell components. The present invention is further a method of forming a manifold for a fuel cell.
a is an enlarged view of the circled portion of
b is a cross-sectional view of the manifold of
c is an enlarged view of the circled portion of
a is a frontal sectional view of a manifold port with baffle taken along section line A-A of
b is a side sectional view of a manifold port with baffle taken along section line B-B of
c is a top view of a manifold port with baffle.
a is perspective view of manifold channel ports mated to a manifold frame using snap fingers.
b is a sectional view taken along section line A-A of
Electrochemical cells comprise an anode, a cathode, an electrolyte in contact with the anode and the cathode, and a flow network comprising a manifold structure having at least one manifold port adapted to engage a corresponding port on the electrochemical cell such that a fluid flow pathway from the manifold port to the corresponding port of the electrochemical cell can be established. In improved embodiments described herein, the manifold port is connected to a frame of the manifold such that the manifold port can move, or float, in at least one direction when not engaged with the electrochemical cell. In some embodiments, the manifold port can comprise structure that engages with a mated structure on the manifold frame such that the manifold port can move over a limited range in at least one dimension relative to the manifold frame while being supported by the manifold frame. Due to the presence of the moving or floating manifold port, the manifold structure can more easily engage and disengage with other components of the electrochemical cell. Moreover, in embodiments where the manifold comprises a plurality of manifold ports, the floating ability of each port can facilitate easy engagement with a plurality of corresponding ports, and can increase the manufacturing tolerances of the manifolds. In some embodiments, each of the plurality of manifold ports can independently float or move, relative to the other manifold ports, which can facilitate coupling each of the ports to a corresponding port. In some embodiments, one or more baffles can be positioned within the fluid channels defined in the manifold ports to facilitate substantially uniform fluid flow out of manifold ports.
Referring to
As shown in the embodiment of
Manifold frame 102 can further comprise one or more fastening structures 122 positioned, for example, around the periphery of manifold frame 102 to facilitate connecting manifold frame 102 to another electrochemical cell structure such as, for example, a cell stack endplate, a mounting bracket or the like. Upward directed threaded studs 123 are included to help facilitate connecting manifold frame 102 to another electrochemical cell structure. The manifold shown in
Generally, manifold frame 102 provides support for the manifold ports, and connected flow tubes, and also provides structure that can secure the manifold to electrochemical cell components. As shown in
The floating engagement of a manifold port with an opening in a manifold frame is also shown in
Referring to
Turning to
The channel port 408 has a ridge 412 and a spaced apart outward directed lip 414. In assembly, channel port 408 is pressed into the opening 404 from the underside. The snap fingers 410 are forcibly spread by the channel port 408. The channel port 408 need not be perfectly aligned with the opening 404, since the snap fingers 410 may spread varying amounts by an off center channel port 408, thereby providing the desired amount of float. As the channel port 408 is fully inserted into the opening 404, the distal end of the snap fingers engage the ridge 412 and the proximal portion of the snap fingers 404 is supported upon the upper surface of the lip 412.
As shown in
In some embodiments, manifold frame 102 can have a generally rectangular cross-section, although other shapes can be used as appropriate. Manifold frame 102 can be composed of any material suitable for use in electrochemical cell applications including metals, polymers and combinations thereof. Suitable metals include, for example, aluminum and stainless steel. Suitable polymers include, for example, poly(vinylchloride) (PVC), polyurethanes, polycarbonates, polyethylene (PE), ultra high molecular weight polyethylene (UHMWPE), poly(tetrafluoroethylene) (PTFE), polyetheretherketone (PEEK), and blends and copolymers thereof.
Referring to
As described above, manifold 100 can comprise a plurality of manifold ports 110, which facilitate connecting manifold 100 to another electrochemical cell component such that a plurality of fluid flow paths between manifold 100 and another cell component are established. As depicted in
Referring to
The manifold ports 110 of the present disclosure can be comprised of any material suitable for use in electrochemical cell applications. Suitable materials include polymers such as, for example, polyethylene (PE), polypropylene (PP), poly(tetrafluoroethylene) (PTFE), poly(vinylidine diflouride) (PVDF), and blends and copolymers thereof. In addition, in embodiments where the manifold 100 is designed to be used with a hydrogen fuel cell, it can be desirable to reduce potential static build up in the manifold ports 110. In these embodiments, a conductive additive can be added to the polymer to form a composite material that can dissipate static. Suitable conductive materials include, for example, carbon powders, carbon fibers, carbon nanotubes, other carbon particles and combinations thereof. In some embodiments, the conductive additive/polymer composite can have a surface resistivity from about 107 ohms/square to about 109 ohms/square.
Generally, the manifold ports 110 of the present invention can be connected to one or more flow tubes, which can provide fluid flow pathways to each of the manifold ports 110. Referring to
The flow tubes of the present disclosure can be formed from any material suitable for use in electrochemical cell applications. Suitable materials include, for example, polymers, copolymers, block copolymers and blends and copolymers thereof. Suitable polymers include, for example, polyethylene (PE), polypropylene (PP), poly(tetrafluoroethylene) (PTFE), poly(vinylidine diflouride) (PVDF), and blends and copolymers thereof. In addition, in embodiments where the manifold 100 is designed to be used with a hydrogen fuel cell, it can be desirable to reduce potential static build up in the flow tubes. In these embodiments, a conductive additive can be added to the polymer to form a composite material that can dissipate static. Suitable conductive materials include, for example, carbon powders, carbon fibers, carbon nanotubes, and combinations thereof. In some embodiments, the conductive additive/polymer composite can have a surface resistivity from about 107 ohms/square to about 109 ohms/square. In some embodiments, the flow tubes are formed by roto molding a composite comprising PVDF and carbon powder and/or carbon fibers. In these embodiments, in order to obtain a molded tube with a smooth surface, it is desirable to employ a composite material having a substantially spherical shape. In other words, roto molding a composite material comprising elongated particles can produce a molded article with undesirable surface features such as, for example, pits and/or grooves. In some embodiments, the length/diameter ratio of the composite material can be about 1:1, while in other embodiments the length to diameter ratio can be from about 1:1 to about 2:1. In some embodiments, the manifold ports can be injection molded and welded to the roto molded flow tubes to form the flow networks of the present disclosure. Roto molding is generally described in, for example, U.S. Pat. No. 4,629,409, entitled “Rotational molding apparatus having robot to open, close, charge and clean mold,” and U.S. Pat. No. 6,599,459, entitled “Method of rotational molding with moveable insert,” both of which are hereby incorporated by reference.
In some embodiments, during use of manifold 100, manifold ports 110a and 110b can be employed to supply air to the cathodes of an electrochemical cell, while manifold ports 118a and 118b can be employed to deliver hydrogen to the anodes. Additionally, manifold ports 116a and 116 can be used as cathode outlet ports, while manifold ports 112a and 112b can used as anode outlet ports. Manifold ports 120a and 120b can be used to supply coolant to an electrochemical cell stack, while manifold ports 114a and 114b can be used as coolant outlet ports. The flow tubes 152, 154, and 156, described above, can be used to supply appropriate fluids to the manifold ports of manifold 100.
Referring again to
The embodiments above are intended to be illustrative and not limiting. Additional embodiments are within the claims. Although the present invention has been described with reference to particular embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.
The present application claims the benefit of U.S. Provisional Application Ser. No. 60/603,300, filed Aug. 20, 2004, included herein in its entirety by reference.
Number | Date | Country | |
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60603300 | Aug 2004 | US |