Patent Application
20050136317
The present invention relates generally to fuel cells and, more particularly, to molded flow field structures for use in discrete and roll-good fuel cell assemblies.
A typical fuel cell system includes a power section in which one or more fuel cells generate electrical power. A fuel cell is an energy conversion device that converts hydrogen and oxygen into water, producing electricity and heat in the process. Each fuel cell unit may include a proton exchange member at the center, electrodes adjacent each side of the proton exchange members and gas diffusion layers adjacent the catalyst layers. Anode and cathode unipolar or bipolar plates are respectively positioned at the outside of the gas diffusion layers.
The reaction in a single fuel cell typically produces less than one volt. A plurality of the fuel cells may be stacked and electrically connected in series to achieve a desired voltage. Electrical current is collected from the fuel cell stack and used to drive a load. Fuel cells may be used to supply power for a variety of applications, ranging from automobiles to laptop computers.
The efficacy of fuel cells as a well established energy generating technology may largely depend on new manufacturing techniques that provide for higher throughputs at reduced material and fabrication costs.
The present invention is directed to a flow field structure for use in a fuel cell assembly. More particularly, the present invention is directed to a molded multi-part flow field structure preferably having a unipolar or monopolar configuration, it being understood that bipolar configurations are also contemplated. A flow field structure, according to one embodiment, includes a molded flow field plate formed of a conductive material comprising a first polymer. A molded frame is disposed around the flow field plate and formed of a non-conductive material comprising a second polymer. Manifolds are formed in the molded frame, and a molded gasket arrangement is disposed proximate a periphery of the manifolds.
According to another embodiment, a flow field structure for use in a fuel cell assembly includes a molded flow field plate formed of a conductive material comprising a first polymer and a molded frame disposed around the flow field plate and formed of a non-conductive material comprising a second polymer. A molded coupling arrangement extends from the frame. The molded coupling arrangement is configured to couple the unipolar flow field structure with other unipolar flow field structures to define a continuous web of the unipolar flow field structures.
In accordance with a further embodiment, a method of forming a flow field structure for use in a fuel cell assembly involves molding a flow field plate and manifolds in the flow field plate using a conductive material comprising a first polymer. A frame is molded around the flow field plate using a non-conductive material comprising a second polymer. A gasket arrangement is molded proximate a periphery of the manifolds.
According to another embodiment, a method of forming a flow field structure for use in a fuel cell assembly involves molding a flow field plate using a conductive material comprising a first polymer, and molding a frame around the flow field plate using a non-conductive material comprising a second polymer. The method further involves molding a coupling arrangement between the flow field structure and other ones of the flow field structure to define a continuous web of the flow field structures.
The above summary of the present invention is not intended to describe each embodiment or every implementation of the present invention. Advantages and attainments, together with a more complete understanding of the invention, will become apparent and appreciated by referring to the following detailed description and claims taken in conjunction with the accompanying drawings.
While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It is to be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims.
In the following description of the illustrated embodiments, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration, various embodiments in which the invention may be practiced. It is to be understood that the embodiments may be utilized and structural changes may be made without departing from the scope of the present invention.
A molded multi-part flow field structure of the present invention may be incorporated in fuel cell assemblies of varying types, configurations, and technologies. A molded multi-part flow field structure preferably has a unipolar or monopolar configuration. A unipolar flow field structure of the present invention may be employed with one or more other unipolar flow field structure to construct fuel cell assemblies of various configurations. Unipolar flow field structure of the present invention may also be employed with one or more bipolar flow field structure to construct fuel cell assemblies of various configurations. Although a molded multi-part flow field structure of the present invention is generally described herein within the context of unipolar configurations, it is understood that bipolar flow field structure may also be constructed in accordance with the principles of the present invention. Accordingly, various embodiments of fuel cell assemblies that incorporate unipolar, bipolar, and both unipolar and bipolar flow field structures are described below for purposes of illustration, and not of limitation.
A typical fuel cell is depicted in
The fuel cell 10 shown in
The electrolyte membrane 16 permits only the hydrogen ions or protons to pass through the electrolyte membrane 16 to the cathode portion of the fuel cell 10. The electrons cannot pass through the electrolyte membrane 16 and, instead, flow through an external electrical circuit in the form of electric current. This current can power an electric load 17, such as an electric motor, or be directed to an energy storage device, such as a rechargeable battery.
Oxygen flows into the cathode side of the fuel cell 10 via the second fluid transport layer 19. As the oxygen passes over the cathode 18, oxygen, protons, and electrons combine to produce water and heat.
Individual fuel cells, such as that shown in
A number of different fuel cell technologies can be employed to construct UCAs in accordance with the principles of the present invention. For example, a UCA packaging methodology of the present invention can be employed to construct proton exchange membrane (PEM) fuel cell assemblies. PEM fuel cells operate at relatively low temperatures (about 175° F./80° C.), have high power density, can vary their output quickly to meet shifts in power demand, and are well suited for applications where quick startup is required, such as in automobiles for example.
The proton exchange membrane used in a PEM fuel cell is typically a thin plastic sheet that allows hydrogen ions to pass through it. The membrane is typically coated on both sides with highly dispersed metal or metal alloy particles (e.g., platinum or platinum/ruthenium) that are active catalysts. The electrolyte used is typically a solid perfluorinated sulfonic acid polymer. Use of a solid electrolyte is advantageous because it reduces corrosion and management problems.
Hydrogen is fed to the anode side of the fuel cell where the catalyst promotes the hydrogen atoms to release electrons and become hydrogen ions (protons). The electrons travel in the form of an electric current that can be utilized before it returns to the cathode side of the fuel cell where oxygen has been introduced. At the same time, the protons diffuse through the membrane to the cathode, where the hydrogen ions are recombined and reacted with oxygen to produce water.
A membrane electrode assembly (MEA) is the central element of PEM fuel cells, such as hydrogen fuel cells. As discussed above, typical MEAs comprise a polymer electrolyte membrane (PEM) (also known as an ion conductive membrane (ICM)), which functions as a solid electrolyte.
One face of the PEM is in contact with an anode electrode layer and the opposite face is in contact with a cathode electrode layer. Each electrode layer includes electrochemical catalysts, typically including platinum metal. Fluid transport layers (FTLs) facilitate gas transport to and from the anode and cathode electrode materials and conduct electrical current.
In a typical PEM fuel cell, protons are formed at the anode via hydrogen oxidation and transported to the cathode to react with oxygen, allowing electrical current to flow in an external circuit connecting the electrodes. The anode and cathode electrode layers may be applied to the PEM or to the FTL during manufacture, so long as they are disposed between PEM and FTL in the completed MEA.
Any suitable PEM may be used in the practice of the present invention. The PEM typically has a thickness of less than 50 μm, more typically less than 40 μm, more typically less than 30 μm, and most typically about 25 μm. The PEM is typically comprised of a polymer electrolyte that is an acid-functional fluoropolymer, such as Nafion® (DuPont Chemicals, Wilmington Del.) and Flemion® (Asahi Glass Co. Ltd., Tokyo, Japan). The polymer electrolytes useful in the present invention are typically copolymers of tetrafluoroethylene and one or more fluorinated, acid-functional comonomers.
Typically, the polymer electrolyte bears sulfonate functional groups. Most typically, the polymer electrolyte is Nafion®. The polymer electrolyte typically has an acid equivalent weight of 1200 or less, more typically 1100, and most typically about 1000.
Any suitable FTL may be used in the practice of the present invention. Typically, the FTL is comprised of sheet material comprising carbon fibers. The FTL is typically a carbon fiber construction selected from woven and non-woven carbon fiber constructions. Carbon fiber constructions which may be useful in the practice of the present invention may include: Toray Carbon Paper, SpectraCarb Carbon Paper, AFN non-woven carbon cloth, Zoltek Carbon Cloth, and the like. The FTL may be coated or impregnated with various materials, including carbon particle coatings, hydrophilizing treatments, and hydrophobizing treatments such as coating with polytetrafluoroethylene (PTFE).
Any suitable catalyst may be used in the practice of the present invention. Typically, carbon-supported catalyst particles are used. Typical carbon-supported catalyst particles are 50-90% carbon and 10-50% catalyst metal by weight, the catalyst metal typically comprising Pt for the cathode and Pt and Ru in a weight ratio of 2:1 for the anode. The catalyst is typically applied to the PEM or to the FTL in the form of a catalyst ink. The catalyst ink typically comprises polymer electrolyte material, which may or may not be the same polymer electrolyte material which comprises the PEM.
The catalyst ink typically comprises a dispersion of catalyst particles in a dispersion of the polymer electrolyte. The ink typically contains 5-30% solids (i.e. polymer and catalyst) and more typically 10-20% solids. The electrolyte dispersion is typically an aqueous dispersion, which may additionally contain alcohols, polyalcohols, such a glycerin and ethylene glycol, or other solvents such as N-methylpyrrolidone (NMP) and dimethylformamide (DMF). The water, alcohol, and polyalcohol content may be adjusted to alter rheological properties of the ink. The ink typically contains 0-50% alcohol and 0-20% polyalcohol. In addition, the ink may contain 0-2% of a suitable dispersant. The ink is typically made by stirring with heat followed by dilution to a coatable consistency.
The catalyst may be applied to the PEM or the FTL by any suitable means, including both hand and machine methods, including hand brushing, notch bar coating, fluid bearing die coating, wire-wound rod coating, fluid bearing coating, slot-fed knife coating, three-roll coating, or decal transfer. Coating may be achieved in one application or in multiple applications.
Direct methanol fuel cells (DMFC) are similar to PEM cells in that they both use a polymer membrane as the electrolyte. In a DMFC, however, the anode catalyst itself draws the hydrogen from liquid methanol fuel, eliminating the need for a fuel reformer. DMFCs typically operate at a temperature between 120-190° F./49-88° C. A direct methanol fuel cell can be subject to UCA packaging in accordance with the principles of the present invention.
Referring now to
In one configuration, a PEM layer 22 is fabricated to include an anode catalyst coating 30 on one surface and a cathode catalyst coating 32 on the other surface. This structure is often referred to as a catalyst-coated membrane or CCM. According to another configuration, the first and second FTLs 24, 26 are fabricated to include an anode and cathode catalyst coating 30, 32, respectively. In yet another configuration, an anode catalyst coating 30 can be disposed partially on the first FTL 24 and partially on one surface of the PEM 22, and a cathode catalyst coating 32 can be disposed partially on the second FTL 26 and partially on the other surface of the PEM 22.
The FTLs 24, 26 are typically fabricated from a carbon fiber paper or non-woven material or woven cloth. Depending on the product construction, the FTLs 24, 26 can have carbon particle coatings on one side. The FTLs 24, 26, as discussed above, can be fabricated to include or exclude a catalyst coating.
In the particular embodiment shown in
In general terms, and as shown in
The cooling side 45 incorporates a cooling arrangement, such as integral cooling channels. Alternatively, the cooling side 45 may be configured to contact a separate cooling element, such as a cooling block or bladder through which a coolant passes or a heat sink element, for example. Various useful fuel cell cooling approaches are described in commonly owned co-pending U.S. Patent Application entitled “Unitized Fuel Cell Assembly and Cooling Apparatus,” Ser. No. 10/295,518, filed on Nov. 15, 2002, which is incorporated herein by reference. The unipolar flow field plates 40, 42 are preferably constructed in accordance with a multi-part molding methodology as described herein.
Returning to
In one configuration, the edge seal systems 34, 36 include a gasket system formed from an elastomeric material. In other configurations, one, two or more layers of various selected materials can be employed to provide the requisite sealing within UCA 20. Such materials include, for example, TEFLON, fiberglass impregnated with TEFLON, an elastomeric material, UV curable polymeric material, surface texture material, multi-layered composite material, sealants, and silicon material. Other configurations employ an in-situ formed seal system, such as those described in commonly owned co-pending U.S. patent application entitled “Unitized Fuel Cell Assembly,” Ser. No. 10/295,292, filed on Nov. 1, 2002 and previously referenced Ser. No. 10/295,518, filed on Nov. 15, 2002, which are incorporated herein by reference.
In another configuration, a gasket arrangement is incorporated into the flow field plates 40, 42 and formed during a molding process. According to one approach, and as discussed in greater detail below, the flow field plates 40, 42 are molded to include a gasket arrangement for the manifolds provided in the flow field plates 40, 42. The gasket arrangement may be formed during molding of the flow field plates 40, 42 or formed during a subsequent molding process. The gasket arrangement may, for example, include one or more raised molded segments of a molded flow field plate 40 or 42. In another approach, one or more channels may be molded into the flow field plates 40, 42 into which one or more gaskets (e.g., o-rings) may be inserted. Such gaskets may each be a closed-cell foam rubber gasket as disclosed in co-pending application Ser. No. 10/294,098, filed Nov. 14, 2002, which is incorporated herein by reference. In other embodiments, and as further discussed below, a gasket arrangement may be molded into the flow field plates 40, 42 with a contact face having a raised-ridge microstructured sealing pattern.
In certain configurations, the gasket system of a separate edge seal system of the type shown in
Similarly, MEA 25b includes a cathode 62b/membrane 61b/anode 60b layered structure sandwiched between FTLs 66b and 64b. FTL 64b is situated adjacent a flow field end plate 54, which is configured as a unipolar flow field plate. FTL 66b is situated adjacent a second flow field surface 56b of bipolar flow field plate 56. It will be appreciated that N number of MEAs 25 and N-1 bipolar flow field plates 56 can be incorporated into a single UCA 50. It is believed, however, that, in general, a UCA 50 incorporating one or two MEAs 56 (N=1, bipolar plates=0 or N=2, bipolar plates=1) is preferred for more efficient thermal management. As discussed previously, a bipolar plate or plates of a UCA may be constructed according to a multi-part molding methodology of the present invention or may be of a conventional construction.
The UCA configurations shown in
For example, the flow field plate 102 and frame 104 can be formed from the same base resin or different resins. It is believed that, by using dissimilar materials for the flow field plate 102 and frame 104, the materials with the best properties and lowest cost can be used for each functional area of the flow field structure 100. A non-limiting, non-exhaustive listing of suitable materials includes elastomeric materials, thermosetting and thermoplastic materials. The frame preferably is made of epoxy, urethane, acrylate, polyester or polypropylene while the flow field plate is made of these same materials or high temperature resins such as polyetheretherketone (PEEK), polyphenylene sulfide, polyphenylene oxide. Most preferably the frame is made of an elastomer such as a thermoplastic urethane (TPU) and the flow field plate is made of injection moldable grade graphite filled thermoplastic. In one illustrative configuration, the flow field plate 102 may be formed from a thermosetting material that is highly loaded with conductive filler, such as a graphite or other carbonaceous conductive filler. The frame 104 may be formed from a thermoplastic material. In another illustrative configuration, both the flow field plate 102 and the frame are formed from a thermoplastic base material.
The flow field structure 100 may be molded using one or a combination of molding techniques. Moreover, the flow field plate 102 and the frame 104 may be molded in the same molding machine or different molding machines. Further, the flow field plate 102 and the frame 104 may be molded in a common molding machine contemporaneously, such as by molding the flow field plate 102 via a first material shot followed shortly thereafter by molding the frame 104 via a second material shot. The first and second shots may occur in the same molding machine or different machines. Also, the first and second shots may occur in the same molding machine without opening the mold between the first and second shots.
A number of molding techniques may be employed and adapted for use in molding a multi-part flow field structure 100 of the present invention. Such molding techniques include compression molding, injection molding, transfer molding, and compression-injection molding, for example. According to one approach, the flow field plate 102 may be formed using a compression molding technique, while the frame 104 may be formed using an injection molding technique. Preferably, both the flow field plate 102 and the frame 104 may be formed using an injection molding technique.
By way of example, a highly filled material may be compression molded to form the flow field plate 102. Once formed, the flow field plate 102 may be transferred robotically or through manual assistance to an injection mold as an insert. The frame 104 may be injected molded around the flow field plate insert. In another approach, a highly filled material may be injection molded to form the flow field plate 102. A material that is not filled may then be injection molded around the flow field plate 102 to form the frame 104. This may be performed in the same mold or different molds.
In yet another approach, a two-shot method within a common mold is employed. One material is injection molded in a first shot to form one of the flow field plate 102 and frame 104, and a second material is injection molded in a second shot to form the other of the flow field plate 102 and frame 104. The second material shot may be delivered after the first material shot is nearly cured. The mold may or may not be opened between the first and second material shots.
For example, an intra-cell feature of the registration arrangement 108 provides for alignment of at least two components of a given fuel cell assembly or UCA. An inter-cell feature of the registration arrangement 108 provides for alignment of at least one component of a given fuel cell assembly or UCA with at least one component of an adjacent fuel cell assembly or UCA. It is noted that a registration arrangement 108 can include one or more features that provide for both inter-cell and intra-cell registration. Use of a molded registration arrangement advantageously obviates the secondary assembly process of inserting registration posts into corresponding registration apertures during fuel cell component assembly.
For example, and as shown in
It is noted that the presence (or absence) of the protruding registration posts 108b from a flow field structure of an assembled UCA can provide a visually perceivable positioning and polarity identification feature for adding another UCA to a fuel cell stack. The presence of protruding registration posts 108b, for example, is readily discernable from the presence of registration recesses 108a. Depending on the particular identification convention adopted, the anode or cathode plate of each fuel cell assembly may be identified by the presence of registration posts 108b, for example. The other of the anode and cathode plate may be identified by the presence of registration recesses 108a.
In one embodiment, the registration posts 108b and recesses 108a may have the same peripheral shape, such that a contact interface between the registration posts 108b and recesses 108a defines a substantially continuous press-fit interface. According to another embodiment, each of the registration posts 108b has an outer surface differing in shape from a shape of the inner surface of the registration recesses 108a. The inner surface of the registration recesses 108a contacts the outer surface of the registration posts 108b at a plurality of discrete press-fit locations.
In one configuration, the shape of at least one of the inner surface of the registration recesses 108a and the outer surface of the registration posts 108b may, for example, define a convex curved shape. The shape of at least one of the inner surface of the registration recesses 108a and the outer surface of the registration posts 108b may also define a generally curved shape comprising a two or more concave or protruding portions. In another configuration, the shape of at least one of the inner surface of the registration recesses 108a and the outer surface of the registration posts 108b may define a circular or an elliptical shape. For example, the shape of one of the inner surface of the registration recesses 108a and the outer surface of the registration posts 108b may define a circle, and the shape of the other of the inner surface of the registration recesses 108a and the outer surface of the registration posts 108b may define an ellipse.
Other shape relationships are possible. For example, the shape of at least one of the inner surface of the registration recesses 108a and the outer surface of the registration posts 108b may define a polygon. The shape of one of the inner surface of the registration recesses 108a and the outer surface of the registration posts 108b, for example, may define a first polygon, and the shape of the other of the inner surface of the registration recesses 108a and the outer surface of the registration posts 108b may define a second polygon. By way of further example, the shape of one of the inner surface of the registration recesses 108a and the outer surface of the registration posts 108b may define a polygon, and the shape of the other of the inner surface of the registration recesses 108a and the outer surface of the registration posts 108b may define a circle or an ellipse. The shape of the inner surface of the registration recesses 108a may also define a triangle, and the outer surface of the registration posts 108b may define a circle. Other illustrative registration post configurations include those having a tapered shape or a wedge shape. Additional details of useful fuel cell registration arrangements are disclosed in commonly owned co-pending U.S. patent application entitled “Registration Arrangement for Fuel Cell Assemblies,” Ser. No. 10/699,454, filed on Oct. 31, 2003, which is incorporated herein by reference.
With continued reference to
As is shown in
The joint 110 preferably incorporates an engagement arrangement that provides a sound mechanical interface between the frame 104 and flow field plate 102. In the configuration shown in
The gasket arrangement 114 is formed as one or more ridges protruding from a surface of the frame 102. In
According to one approach, the gasket arrangement 114 is formed during molding of the frame 104. In another approach, the gasket arrangement 114 is molded to a previously formed frame 104 in a subsequent molding process. Molding the gasket arrangement 114 in a molding process separate from the frame 104 allows for greater selectivity of materials for the various functional regions of a flow field structure 100. For example, in certain applications, it may be desirable to form the gasket arrangement 114 using the same material as is used to form the frame 104. In other applications, it may be desirable to form the gasket arrangement 114 using a material dissimilar to that used to form the frame 104. For example, the polymeric material used to mold the gasket arrangement 114 to the frame 104 may have a hardness less than that of the frame material. Molding the flow field plate 102, frame 104, and gasket 114 using materials that are optimal for these components provides the opportunity to produce a flow field structure 100 that can be designed for use in a wide range of applications, and further provides the opportunity to more effectively balance performance and cost requirements.
According to one embodiment, the microstructured sealing pattern 116 comprises a raised-ridge microstructured contact pattern. In this configuration, the raised-ridge microstructured contact pattern preferably incorporates a hexagonal pattern, which may include a degenerate hexagonal pattern, for example. The raised-ridge microstructured contact pattern may, in general, comprise ridges that meet at joining points, wherein no more than three ridges meet at any one joining point. The raised-ridge microstructured contact pattern is typically composed of cells so as to localize and prevent spread of any leakage.
By way of non-limiting example, the ridges that comprise the raised-ridge microstructured contact pattern may have an unladen width of less than 1,000 micrometers, more typically less than 600 micrometers, and most typically less than 300 micrometers, and typically have a depth (height) of no more than 250 micrometers, more typically less than 150 micrometers, and most typically less than 100 micrometers. The microstructure sealing pattern 116 shown in
In
The coupling arrangement shown in
The carrier strips 120a, 120b may be formed to incorporate an overmold region 124, an exploded view of which is provided in
Returning to
As was discussed previously, the coupling arrangement 310 includes an overmold region that forms an interlocking arrangement and may also include a living hinge (see, e.g.,
After completion of the first shot and expiration of an appropriate curing duration, the slides 306a, 306b are upwardly displaced to a position coplanar with respect to the upper surface of the flow field plate 102b. The slides 301a, 301b are downwardly displaced so that upper surfaces of the slides 301a, 301b are coplanar with respect to a lower surface of the flow field plate 102b. Downward movement of the slides 301a, 301b permit the spring loaded cores 308a, 308b to move to a downward position as shown in
After completion of the second shot and expiration of an appropriate curing duration, the mold halves 302, 304 separate, and the multi-part molded flow field structure 102b is separated from the mold cavity and moved robotically or through manual assistance into a staging position adjacent the exit of the mold cavity. The slides and cores of the mold 300 are moved to appropriate positions and another multi-part flow field structure is molded in a manner described above. In this manner, a continuous web of molded flow field structures may be produced. This web may be subject to a winding operation to produce a roll-good of flow field structures.
A web of flow field structures produced in accordance with the present invention can be rolled up as a roll-good for future use in a fuel cell assembly operation. Alternatively, and as shown in
In general, an MEA web 320 is transported so that individual MEAs 320a of the MEA web 320 register with a pair of flow field structures 100u′, 100L′ from the first and second flow field plate webs 100u, 100L. After encasing the MEAs 320a between respective pairs of flow field structures 100u′, 100L′, the resulting UCA web 330 may be further processed by a sealing station and/or a winding station. A web 330 of sealed UCAs can subsequently be subject to a singulation process to separate individual UCAs from the UCA web 330.
It is noted that the UCA configurations shown in various Figures and discussed herein are representative of particular arrangements that can be implemented for use in the context of the present invention. These arrangements are provided for illustrative purposes only, and are not intended to represent all possible configurations coming within the scope of the present invention. For example, a molding process for producing flow field structures as described above may dictate use of certain UCA features, such as additional or enhanced sealing features, gasket features, and/or hard and soft stop features. Conversely, such a molding process may provide for elimination of certain UCA features, such as elimination of a separate gasket or sealing feature by substitute use of material molded around the manifolds and/or edge portions of the flow field structures.
A variety of UCA configurations can be implemented with a thermal management capability in accordance with other embodiments of the present invention. By way of example, a given UCA configuration can incorporate an integrated thermal management system. Alternatively, or additionally, a given UCA can be configured to mechanically couple with a separable thermal management structure. Several exemplary UCA thermal management approaches are disclosed in previously incorporated U.S. patent application Ser. Nos. 10/295,518 and 10/295,292.
The fuel cell system 400 includes a fuel processor 404, a power section 406, and a power conditioner 408. The fuel processor 404, which includes a fuel reformer, receives a source fuel, such as natural gas, and processes the source fuel to produce a hydrogen rich fuel. The hydrogen rich fuel is supplied to the power section 406. Within the power section 406, the hydrogen rich fuel is introduced into the stack of UCAs of the fuel cell stack(s) contained in the power section 406. A supply of air is also provided to the power section 406, which provides a source of oxygen for the stack(s) of fuel cells.
The fuel cell stack(s) of the power section 406 produce DC power, useable heat, and clean water. In a regenerative system, some or all of the byproduct heat can be used to produce steam which, in turn, can be used by the fuel processor 404 to perform its various processing functions. The DC power produced by the power section 406 is transmitted to the power conditioner 408, which converts DC power to AC power for subsequent use. It is understood that AC power conversion need not be included in a system that provides DC output power.
The power section 506 of the fuel cell power supply system 500 produces DC power, useable heat, and clean water. The DC power produced by the power section 506 may be transmitted to the power conditioner 508, for conversion to AC power, if desired. The fuel cell power supply system 500 illustrated in
In the implementation illustrated in
In another implementation, illustrated in
The foregoing description of the various embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto.
