Abstract:
A manifold for a fuel cell includes 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. A method of forming a manifold for a fuel cell is further included.

Description:
RELATED APPLICATION  
       [0001]     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. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The invention pertains to an electrochemical cell, and in particular to an electrochemical cell comprising a manifold with positionable ports.  
       BACKGROUND OF THE INVENTION  
       [0003]     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.  
         [0004]     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.  
         [0005]     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.  
         [0006]     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.  
       SUMMARY OF THE INVENTION  
       [0007]     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.  
         [0008]     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.  
         [0009]     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.  
         [0010]     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.  
         [0011]     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.  
         [0012]     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.  
         [0013]     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.  
         [0014]     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.  
         [0015]     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.  
         [0016]     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. 
     
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0017]      FIG. 1  is a top view of a manifold having a plurality of floating or moving manifold ports.  
         [0018]      FIG. 2  is a top perspective view of the manifold of  FIG. 1 .  
         [0019]      FIG. 3  is a bottom perspective view of the manifold of  FIG. 1  rotated 90 degrees to show flow tubes that can be connected to the manifold ports, with a cell stack shown connected to the manifold in dashed lines.  
         [0020]      FIG. 4  is a cross-sectional view of the manifold of  FIG. 1 , the cross-section taken along line c-c of  FIG. 1 .  
         [0021]      FIG. 5   a  is an enlarged view of the circled portion of  FIG. 4  showing a groove located inside an opening in a manifold body engaged with a protrusion on the port located within the opening.  
         [0022]      FIG. 5   b  is a cross-sectional view of the manifold of  FIG. 1 , the cross-section taken along line d-d.  
         [0023]      FIG. 5   c  is an enlarged view of the circled portion of  FIG. 5   b  showing a groove located inside an opening in a manifold body engaged with a protrusion on the port located within the opening.  
         [0024]      FIG. 6  is a cross-section view of an alternate coupling mechanism that facilitates a floating or moving manifold port.  
         [0025]      FIG. 7  is a top view of a port that can be employed in the manifolds of the present disclosure.  
         [0026]      FIG. 8  is a bottom view of the port of  FIG. 7 .  
         [0027]      FIG. 9  is a top perspective photo of a manifold of the present disclosure.  
         [0028]      FIG. 10  is a bottom perspective photo of the manifold of  FIG. 9 .  
         [0029]      FIG. 11  is side photo of the manifold of  FIG. 9 .  
         [0030]      FIG. 12  is a schematic diagram of a cell stack interfaced with a manifold that is connected to a hydrogen source, an oxygen source and a coolant source.  
         [0031]      FIG. 13   a  is a frontal sectional view of a manifold port with baffle taken along section line A-A of  FIG. 13   a.    
         [0032]      FIG. 13   b  is a side sectional view of a manifold port with baffle taken along section line B-B of  FIG. 13   a.    
         [0033]      FIG. 13   c  is a top view of a manifold port with baffle.  
         [0034]      FIG. 14  is a perspective sectional view of an overmolded manifold port with baffle.  
         [0035]      FIG. 15  is a section view of a manifold with pin connectors connecting the port to the manifold frame.  
         [0036]      FIG. 16   a  is perspective view of manifold channel ports mated to a manifold frame using snap fingers.  
         [0037]      FIG. 16   b  is a sectional view taken along section line A-A of  FIG. 16   a  of the manifold channel port mated to the manifold frame using snap fingers.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0038]     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.  
         [0039]     Referring to  FIGS. 1-3 , a manifold  100  is shown comprising manifold frame  102 . Manifold frame  102  can include a top face  104  and an opposed bottom face  106 . Generally, manifold frame  102  can be provided with one or more openings  108   a - l , wherein each opening defines a passage though manifold frame  102 . In some embodiments as depicted in  FIG. 2 , a manifold port  110  can be positioned within each opening  108   a - l , and thus the size and shape of each opening can be guided by the corresponding size and shape of the manifold port  110  (in the description, a manifold port is generically noted by the reference numeral  110 , although other reference numerals are used to denote manifold ports of differing design) adapted to fit into the specific opening  108 . In some embodiments, the plurality of openings  108   a - j  can have substantially the same size and shape, while in other embodiments the plurality of openings  108   a - l  can have different sizes and shapes from each other. Referring to  FIG. 2 , twelve openings  108  are shown with four, openings  108   b, g, j , and  k , having a common size and shape and the other eight, openings  108   a, c, d - f, h, i , and  l , having a common size and shape.  
         [0040]     As shown in the embodiment of  FIGS. 1-3 , manifold  100  can comprise a plurality of manifold ports  110   a ,  110   b ,  112   a ,  112   b ,  114   a ,  114   b ,  116   a ,  116   b ,  118   a ,  118   b ,  120   a  and  120   b , each of the manifold ports  110   a ,  110   b ,  112   a ,  112   b ,  114   a ,  114   b ,  116   a ,  116   b ,  118   a ,  118   b ,  120   a  positioned within a respective one of the openings  108   a - l  in manifold frame  102 . As shown in  FIG. 2 , the openings  121  of each of the manifold ports  110   a ,  110   b ,  112   a ,  112   b ,  114   a ,  114   b ,  116   a ,  116   b ,  118   a ,  118   b ,  120   a  can all be aligned in substantially the same direction (the Z direction in the depiction of  FIG. 2 ) to facilitate quick connection to a cell stack endplate or another electrochemical cell component. Although  FIGS. 1-3  shown an embodiment where twelve manifold ports  110   a ,  110   b ,  112   a ,  112   b ,  114   a ,  114   b ,  116   a ,  116   b ,  118   a ,  118   b ,  120   a  are provided in manifold  100 , one of ordinary skill in the art will recognize that manifolds with different numbers of manifold ports, e.g., greater or smaller than twelve, are contemplated and are within the disclosure. Additionally, the number of manifold ports in a particular manifold can be guided by the corresponding design of the electrochemical cell stack that the manifold is designed connect with. As described below, each manifold port is generally connected to one or more flow pipes  154  to facilitate moving desired fluids through the respective manifold port  110   a ,  110   b ,  112   a ,  112   b ,  114   a ,  114   b ,  116   a ,  116   b ,  118   a ,  118   b ,  120   a.    
         [0041]     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  FIGS. 1-3  is designed to couple to two cell stacks. One of ordinary skill in the art will recognize that the manifold  100  could be adapted to couple to a different number cell stacks with a corresponding change in manifold design.  
         [0042]     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  FIG. 5   a , in some embodiments, each of the plurality of openings  108   a - l  in the manifold frame  102  can have a peripheral groove or channel  124  that extends along edges of the opening  108   a - l . For example, as shown in  FIG. 5   a , which is an enlarged view of the encircled portion of  FIG. 4 , groove  124  can be located within opening  108   f  and can be adapted to engage a corresponding rim or tongue  126  on port  120   a , which permits port  120   a  to move, or float, in at least one dimension (e.g., in the xy plane, as depicted in  FIG. 2 ) while positioned in opening  108   f . The rim  1226  outer margin  123  is spaced apart from the groove  124  inner margin  125 . The height dimension of the rim  124  may be less than the height dimension of the groove  124  such that there is spacing for float in the Z direction as well. This spacing is apparent in  FIG. 5   a . Thus, during engagement of manifold port  120   a  with a corresponding port located on an electrochemical cell component, manifold port  120   a  can move or float at least laterally in the XY directions, which can facilitate easier alignment and connection.  
         [0043]     The floating engagement of a manifold port with an opening in a manifold frame is also shown in  FIGS. 5   b  and  5   c . In some embodiments, each manifold port in a first component can float or move independently of the other manifold ports, which facilitates aligning a plurality of manifold ports with a plurality of corresponding ports in a second component, the second component to be mated to the first component. As noted above, in some embodiments, the manifold ports can float in the x-y axis from about ¼ of an inch to about  1 / 16  of an inch. In some embodiments, the manifold ports, such as manifold port  120   a , can float, or move, in the z-axis. Such movement is typically about 1/32 of an inch or less. Additionally, in some embodiments, the manifold ports  120   a  can float in the x-y axis from about 2 to about 6 times the distance that manifold ports  120   a  can float in the z-axis. However, in other embodiments, two or more manifold ports  120   a  may be connected to a common flow tube  154 . In these embodiments, desired levels of independent manifold port movement can be maintained by employing of a flexible and/or elastomeric flow tube material that will permit the coupled ports to move relative to one another.  
         [0044]     Referring to  FIG. 15 , a third way of generating the float noted above is depicted. In this case the manifold frame  102  of the manifold  100  has an oversized bore  170  defined therein. As noted, the bore is preferably 0.375 inch in diameter. The manifold port  110  has an upward directed pin  172  that is disposable in the bore  170 . As noted, the pin  152  preferably has a diameter of 0.250 inch. Accordingly, the pin  172  is free to float in the XY plane within the oversize bore  170 . It should be noted that in this embodiment, the mating to the manifold port  110  to the frame  102  in the Z direction is preferably relatively snug, as indicated by the dimension noted at  176 , wherein clearance is preferably 0.005-0.010 inch. It should be noted that other dimensions of the bore  170  and the pin  172  could be used as desired, depending on the application, in order to achieve the desired float in both the XY plane and in the Z direction.  
         [0045]     Turning to  FIGS. 16   a  and  16   b , a further means of generating float is depicted. In this case, a peripheral frame  400  supports a frame plate  402 . The frame  400  is disposable in the manifold  100 . An opening  404  is defined in the frame plate  402  for each manifold channel port  408  to be mated to the plate  402 . The opening  404  is surrounded by a plurality of peripheral snap fingers  410 . The snap fingers  410  are formed of a resilient material and are spreadable with the snap fingers  410  snapping back to an original disposition after a spreading influence is removed.  
         [0046]     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 .  
         [0047]     As shown in  FIG. 3 , manifold  100  can comprise ports  121   a ,  121   b  and  121   c , which can be connected to, for example, an anode outlet unit or another electrochemical cell component. In some embodiments, ports  121   a ,  121   b  and  121   c  can be floating ports, having the rim and groove structures discussed above on the port  120   a  and opening to permit the ports to move in at least one dimension prior to engaging a corresponding port.  
         [0048]     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.  
         [0049]     Referring to  FIG. 6 , an alternate coupling mechanism is shown that can permit a manifold port to float or move within an opening in a manifold frame.  FIG. 6  shows a manifold port  200  coupled with a corresponding port  210  on a cell stack endplate  201 . As shown in  FIG. 6 , manifold port  200  can comprise a channel  202  adapted to engage protrusion  204  on a manifold frame, which permits manifold port  200  to move in at least one dimension when not engaged with corresponding port  210 . Additionally, port  200  can comprise slot  206  which can engage a corresponding protrusion  208  located on a cell stack endplate  201 , which can roughly align port  200  with a corresponding port  210  during engagement. As shown in  FIG. 6 , manifold port  200  can be connected to a flow tube  212  to facilitate moving fluids to and from manifold port  200 .  
         [0050]     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  FIGS. 13   a - c  and  14 , generally, each manifold port  110  can comprise a port body  111  and a fluid channel  113  that is defined by and that extends though the port body  111 . One end of the bore can be connected to a flow pipe, while the opposite end of the bore can form an opening adapted to engage with a corresponding port on another fuel cell component. Additionally, an o-ring  115  or the like can be positioned in a groove  119  defined in the port body  111  to facilitate sealing port  110  to a corresponding opening  108 . In general, the o-ring can be composed of, for example, natural rubber, synthetic rubber, and the like and combinations thereof.  
         [0051]     Referring to  FIGS. 7 and 8 , a manifold port  110  shown comprising port body  111  and fluid channel  113  extending through port body  111  such that fluid channel  113  defines a fluid flow pathway through port  110 . In some embodiments, end  134  of port  129  can be adapted to engage with a fluid flow pipe, while opposed end  136  can be adapted to engage a corresponding port on another fuel cell component, such as a corresponding port on a fuel cell stack endplate. In some embodiments, one or more baffles  138 ,  140  ( FIG. 7 ),  142 ,  144  ( FIGS. 8, 13   a - c , and  14 ) can be positioned within fluid channel  113  to alter the flow of fluids though fluid channel  113 . Generally, the baffles  138 ,  140 ,  142 , and  144  are designed to disperse fluid flow across the opening of fluid channel  113  such that a more uniform flow out of end  136  is achieved relative to corresponding flow without the baffle(s)  138 ,  140 ,  142 , and  144  by restricting flow at the center  143  of the port  100  and forcing flow toward the outer edges  145  along the length of the port  110 . See  FIG. 14 . One of ordinary skill in the art will recognize that the geometry and number of the baffle(s) employed in a particular manifold port  110  can be guided by the flow of incoming fluids and the desired flow streams for a particular electrochemical cell design.  
         [0052]     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 10 7  ohms/square to about 10 9  ohms/square.  
         [0053]     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  FIGS. 1-3 , in some embodiments, flow tube  150  can be connected to manifold ports  120   a  and  120   b , while flow tube  152  can be connected to manifold port  116   a . In some embodiments, flow tube  154  can be connected to manifold port  110   a , while flow tube  154  can be connected to manifold port  110   b . Flow tube  156  can be connected to manifold port  116   b , while flow tube  158  can be connected to manifold ports  114   a  and  114   b . Flow tubes  159   a  and  159   b  can be connected to manifold ports  118   a  and  118   b , respectively. Flow tubes  160   a  and  160   b  can be connected to manifold ports  112   a  and  112   b , respectively. One or ordinary skill in the art will recognize that the connection of specific flow tubes to specific manifold ports can be guided by the design and fluid flow requirements of a particular electrochemical cell stack.  
         [0054]     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 10 7  ohms/square to about 10 9  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.  
         [0055]     In some embodiments, during use of manifold  100 , manifold ports  110   a  and  110   b  can be employed to supply air to the cathodes of an electrochemical cell, while manifold ports  118   a  and  118   b  can be employed to deliver hydrogen to the anodes. Additionally, manifold ports  116   a  and  116  can be used as cathode outlet ports, while manifold ports  112   a  and  112   b  can used as anode outlet ports. Manifold ports  120   a  and  120   b  can be used to supply coolant to an electrochemical cell stack, while manifold ports  114   a  and  114   b  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 .  
         [0056]      FIGS. 9-11  depict a typical manifold  100  with various ports, oval and round, and other components identified by function. The oval ports  110  include the following: 
        port  110   a  cathode in stage  1      port  110   b  coolant out stage  1      port  110   c  coolant out stage  2      port  110   d  cathode out stage  2      port  110   e  coolant in stage  2      port  110   f  coolant in stage  1      port  110   g  cathode out stage  1      port  110   h  cathode in stage  2  
 
 Also included are round ports  312 , including the following: 
    port  312   a  anode out stage  1      port  312   b  anode out stage  2      port  312   c  anode in stage  2      port  312   d  anode in stage  1  
 
 Additionally included are hose connections  314  including the following: 
     314   a  cathode out stage  2       314   b  coolant out stage  2       314   c  cathode in stage  2       314   d  cathode exhaust      314   e  cathode in stage  1       314   f  coolant in stage  1       314   g  cathode in stage  2       314   h  anode in stage  1       314   i  anode in stage  2       314   j  coolant in drain      314   k  coolant out drain      314   l  anode out bleed      314   m  anode out stage  2       314   n  anode out drain 
 
 Other components include the following: 
     316  electrical connection      318   a  DP sensor port, anode in stage  2       318   b  DP sensor port, anode in stage  1           
         [0086]     Referring again to  FIG. 14 , the use of overmolding for a manifold port  110  is depicted. The present invention includes in one embodiment, at least one over molded port connection  110 . The outer body  300  of the port  110  is preferably formed of a metal, preferably stainless steel. The inner portion  302  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  300 , as depicted at the interface  304  of the outer body  300  and the inner portion  302 . All surfaces  306  that contact the fluid media are then formed of impervious plastic material, while the metallic body  300  provides the structural strength to withstand a known burst pressure (typically, 414 kpa). Further, the metallic frame  300  may be formed with integral mounting pins  308  for effecting the mating of fuel cell components.  
         [0087]      FIG. 12  shows a schematic diagram of an electrochemical cell system comprising a manifold  250  of the present disclosure interfacing with a cell stack  252 . As shown in  FIG. 12 , the floating ports  254  on manifold  250  can engage corresponding ports  256  on cell stack  252 . Additionally, ports  254  on manifold  250  can be connected to flow tubes, such as flow tubes  152 ,  154 , and  156 , such that manifold  252  can be in fluid communication with, for example, a hydrogen source  258 , an oxygen source  260  and a coolant source  262 . Thus, manifold  250  can direct the flow of fluids from a plurality of fluid sources into appropriate ports  110  of cell stack  252 . Manifold  250  can also direct the flow of fluids of out cell stack  252  as shown in  FIG. 12 . In some embodiments, the electrochemical cell of  FIG. 12  can form part of an automobile or other vehicle.  
         [0088]     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.