WO2006024124A1

WO2006024124A1 - Apparatus for removably attaching an electrochemical cell stack to its operating system

Info

Publication number: WO2006024124A1
Application number: PCT/CA2004/001545
Authority: WO
Inventors: Ricardo Bazzarella; Todd A. Simpson
Original assignee: Hydrogenics Corporation
Priority date: 2004-08-30
Filing date: 2004-08-30
Publication date: 2006-03-09

Abstract

A mounting structure for fuel cell stacks includes a support structure having a position where one or more fuel cell stacks can be removably mounted, and a balance-of-plant for operating the fuel cell stack(s). At least a portion of the balance-of-plant is mounted to the support structure. At least one connection manifold is connected in fluid communication with the balance-of-plant, and is movable relative to the support structure. The connection manifold is configured to sealingly engage the fuel cell stack(s) to define fluid communication paths between process fluid inlets and outlets of the fuel cell stack(s) and corresponding process fluid inlets and outlets on the balance-of-plant.

Description

Apparatus for removably attaching an electrochemical cell stack to its operating system

Field of the invention [0001] The present invention relates to a method and an apparatus for removably attaching an electrochemical cell stack to its operating system.

Background of the invention

[0002] Fuel cells and electrolyzer cells are generally referred to as electrochemical cells. Fuel cells have been proposed as a clean, efficient and environmentally friendly power source having various applications. A conventional proton exchange membrane (PEM) fuel cell is typically comprised of an anode, a cathode, and a selective electrolytic membrane disposed between the two electrodes. A fuel cell generates electricity by bringing a fuel gas (typically hydrogen) and an oxidant gas (typically oxygen) respectively to the anode and the cathode. In reaction, a fuel such as hydrogen is oxidized at the anode to form cations (protons) and electrons by the reaction Hb = 2H+ + 2e-. The proton exchange membrane facilitates the migration of protons from the anode to the cathode while preventing the electrons from passing through the membrane. As a result, the electrons are forced to flow through an external circuit thus providing an electrical current. At the cathode, oxygen reacts with electrons returned from the electrical circuit to form anions. The anions formed at the cathode react with the protons that have crossed the membrane to form liquid water as the reaction by¬ product following O₂ + 2H+ + 2e- = H₂O. [0003] On the other hand, an electrolyzer uses electricity to electrolyze water to generate oxygen from its anode and hydrogen from its cathode. Similar to a fuel cell, a typical solid polymer water electrolyzer (SPWE) or proton exchange membrane (PEM) electrolyzer is also comprised of an anode, a cathode and a proton exchange membrane disposed between the two electrodes. Water is introduced to, for example, the anode of the electrolyzer which is connected to the positive pole of a suitable direct current voltage. Oxygen is produced at the anode by the reaction H₂O = O₂ + 2H+ + 2e-. The protons then migrate from the anode to the cathode through the membrane. On the cathode which is connected to the negative pole of the direct current voltage, the protons conducted through the membrane are reduced to hydrogen following 2H+ + 2e- = hb. [0004] In practice, fuel cells are not operated as single units. Rather, fuel cells are connected in series, either stacked one on top of the other or placed side by side. The series of fuel cells, referred to as a fuel cell stack, is normally enclosed in a housing. The fuel and oxidant are directed through apertures in the housing to the electrodes. The fuel cell is cooled by either the reactants or a cooling medium. The fuel cell stack also comprises current collectors, cell-to-cell seals and insulation while the required piping and instrumentation are provided external to the fuel cell stack. The fuel cell stack, housing and associated hardware constitute a fuel cell module. Likewise, electrolyzer cells are also typically connected in series to form an electrolyzer stack.

[0005] Fuel cell stacks have been used as power sources in various applications, such as fuel cell powered electric vehicles, residential power generators, auxiliary power units, uninterrupted power sources, etc. For fuel cell stacks to be used in power generation applications, many peripheral devices, conditioning devices are needed since fuel cell stacks rely on peripheral preconditioning devices for optimum or even proper operation. Extensive piping and plumbing work is also required for connection between such devices.

[0006] For example, in the situation where the fuel gas of the fuel cell stack is not pure hydrogen, but rather hydrogen containing material (e.g. natural gas), a reformer is usually required in the fuel delivery subsystem for reforming the hydrogen containing material to provide pure hydrogen to the fuel cell stack. Moreover, in the situation where the electrolyte of the fuel cell is a proton exchange membrane, since most of the membranes currently available require a wet surface to facilitate the conduction of protons from the anode to the cathode, and otherwise to maintain the membranes electrically conductive, a humidifier is usually required to humidify the fuel or oxidant gas before it comes into the fuel cell stack. In addition, most conventional fuel cell systems utilize several heat exchangers in gas and coolant delivery subsystems to dissipate the heat generated in the fuel cell reaction, provide coolant to the fuel cell stack, and heat or cool the process gases. In some applications, the process gases or coolant may need to be pressurized before entering the fuel cell stack, and therefore, compressors and pumps may be added to the delivery subsystems. These peripheral devices are usually referred to, collectively, as the "Balance-of-Plant" (BOP), and this term encompasses any peripheral device necessary for the operation of a particular fuel cell stack configuration.

[0007] A common problem that has to be addressed, in connecting the

BOP to a cell stack, is the secure and leak-resistant connection of process fluid streams and electrical or mechanical connections for control equipment, such as fluid conduits and sensors, to the cell stack process fluid inlets and outlets. At a minimum, anode in/out and cathode in/out fluid flow conduit connections must be made to the stack, and a fuel cell also typically has cooling fluid flow conduit connections (thus, coolant is included herein within the meaning of the term "process fluids"). For reasons of manufacturing convenience and/or to optimize fluid flows, ports or apertures on fuel cell stacks are often of non-standard and non-circular shape, requiring some sort of adapter fitting if they are to be connected to standard hoses and the like. Further, a variety of process parameters are measured using different sensors, for example pressure and temperature, and the sensors are advantageously attached to the conduits as close to the desired measurement spot in the system as possible.

[0008] All these fluid flow connections and electrical/mechanical sensor connections generally make it cumbersome and time consuming to disconnect the stack from its balance-of-plant, because each connection must be removed individually. Some attempts have been made to overcome this problem. - A -

[0009] U.S. patent 6,692,859 to Mukerjee et al. discloses a fuel and air supply base manifold for modular solid oxide fuel cells. The manifold has planar surfaces having apertures defined therein for process fluid flow. These apertures mate with process fluid inlets and outlets on a fuel cell stack that can be bolted to the manifold.

[0010] U.S. patent 6,110,612 to Walsh discloses a similar manifold having planar surfaces with process fluid flow apertures that can mate with process fluid inlets and outlets on a fuel cell stack when the stack is bolted to the manifold. [0011] Both the Walsh and Mukerjee et al. manifolds have complex internal structures that may increase the complexity of manufacturing operations. Furthermore, these structures require that the process fluid connection points be located at the position where the fuel cell stack will be supported, thereby limiting design options for both the fuel cell stack and the support structure for the fuel cell stack.

[0012] Therefore, there remains a need for a stack to balance-of-plant connection method that is easy to use, compact and effective, and which will allow a reasonably fast disconnection of the stack should it be desirable or necessary, without limiting the position at which a fuel cell stack can be attached to a support structure.

Summary of the invention

[0013] In one aspect, the present invention is directed towards a mounting structure for fuel cell stacks. The mounting structure comprises a fuel cell stack support structure that has at least one receiving location in which at least one fuel cell stack can be removably mounted, and a balance- of-plant, at least a portion of which is mounted to the fuel cell stack support structure. The mounting structure further comprises at least one connection manifold that is connected in fluid communication with the balance-of-plant. The at least one connection manifold has at least one mating surface configured to matingly and sealingly engage at least one correspondingly configured mating surface on at least one fuel cell stack so as to define fluid communication paths between process fluid inlets and outlets of the at least one fuel cell stack and corresponding process fluid inlets and outlets on the balance-of-plant. The at least one connection manifold is movable relative to the fuel cell stack support structure and the fuel cell stack. [0014] In another aspect, the present invention is directed to a manifold for connection to a fuel cell stack, the manifold comprising: one connector for connection to balance-of-plant for a first process gas flow and a corresponding first aperture in fluid communication with the first connector, for sealing engagement with a corresponding port with a fuel cell stack; a second connector for connection to the balance-of-plant for a second process gas flow and a second aperture in fluid communication with the second connector and for sealing engagement with a corresponding port of a electrochemical cell stack; whereby, in use, to provide for both inflow and outflow of the first and second process gases, a pair of the manifolds at least are connected to the electrochemical cell stack..

[0015] Preferably, the at least one connection manifold comprises two connection manifolds, and still more preferably the at least one connection manifold comprises a first connection manifold connectible in fluid communication with an anode process fluid inlet and a cathode process fluid outlet of the fuel cell stack, and a second connection manifold connectible in fluid communication with a cathode process fluid inlet and an anode process fluid outlet of the fuel cell stack.

[0016] Also preferably, the at least one connection manifold comprises a sensor for sensing a process parameter and which is connected in electrical communication with a control system. Each at least one manifold also preferably comprises a water collection vessel disposed at a lower end thereof and positioned adjacent a process fluid inlet or outlet.

[0017] In a preferred embodiment, the at least one mating surface on the at least one connection manifold is planar. [0018] The at least one manifold may be connected by flexible fluid conduits to the balance of plant, and may additionally or alternatively be movably mounted to the fuel cell stack support structure.

[0019] A further aspect of the present invention provides an electrochemical cell stack, including two groups of spaced apart ports, wherein the electrochemical cell stack is adapted to have at least two process fluids flowing therethrough, with each process fluid having an inlet port in one group of ports and an outlet in the other group of ports, and wherein one manifold is provided for one group of ports and a separate, second manifold is provided for the other group of ports, each manifold including, for each process fluid flow, a connector for connection to balance-of-plant and an aperture in fluid communication with the corresponding connector and adapted for sealing engagement with the electrochemical cell stack.

Brief description of the drawings [0020] Figure 1 is an elevated perspective view of an electrochemical cell system, in accordance with a first embodiment of the present invention, showing an electrochemical cell stack and its balance-of-plant mounted to a bracket;

[0021] Figure 2A is a perspective view of a first connection manifold of an electrochemical cell stack, in accordance with the first embodiment of the present invention, showing a first side thereof having process fluid conduit attachments and sensor attachments;

[0022] Figure 2B is a perspective view of the first connection manifold of Figure 2A, showing a second side thereof having fluid flow apertures and seals to cooperate with anode inlet/outlet apertures of the stack;

[0023] Figure 3A is a perspective view of a second connection manifold of an electrochemical cell stack, in accordance with the first embodiment of the present invention showing a side thereof having process fluid conduit attachments and sensor attachments; [0024] Figure 3B is a perspective view of the second connection manifold of Figure 3A, showing a second side thereof having fluid flow apertures and seals to cooperate with cathode inlet/outlet apertures of the stack; [0025] Figure 4 is an elevated perspective view of an electrochemical cell stack, in accordance with the first embodiment of the present invention, showing the first connection manifold and the second connection manifold attached to the stack;

[0026] Figure 5 is an elevated perspective view of an electrochemical cell system, in accordance with a second embodiment of the present invention, showing an electrochemical cell stack mounted to a bracket and showing a balance-of-plant attached to the bracket, with a stack cover covering the stack;

[0027] Figure 6 is an elevated perspective view of the electrochemical cell system as shown in Figure 5, showing the system with the stack cover removed;

[0028] Figure 7 is an elevated perspective view of the electrochemical cell system as shown in Figure 6, seen from a different angle; and

[0029] Figures 8a and 8b are planar and side views of a further embodiment of the present invention, incorporating common manifolds for two adjacent fuel cell stacks.

Detailed description of the invention

[0030] An electrochemical cell system 10 is shown in Figure 1. A bracket 16 has a receiving location on which an electrochemical cell stack 12 is removably mounted. A balance-of-plant 14 is also mounted on the bracket 16. Although in the embodiment shown, the entire balance-of-plant 14 is mounted on the bracket 16, one skilled in the art will appreciate that a portion of the balance-of-plant 14, rather_.than the entire balance-of-plant 14, may be mounted on the bracket 16, without departing from the scope of the present invention. [0031] A particular embodiment of a mounting structure according to the present invention comprises a first connection manifold 18 and a second connection manifold 20. The cell stack 12 has a first mating surface 22 shaped to receive the first connection manifold 18 and second connection manifold 20, each of which has a second mating surface (not, shown in Figure 1) shaped to mate with (i.e. matingly engage) the first mating surface 22 on the cell stack 12. In the particular embodiment shown, the first mating surface 22 and the second mating surfaces (not shown in Figure 1) are planar; other mating shapes may also be used. While the mating surface 22 is described as a single surface, it will be understood that it can be two separate surfaces, one for each manifold, that need not necessarily be flat and coplanar.

[0032] The first connection manifold 18 is movable relative to the bracket 16, and is removably connected to the anode inlet side (not shown) of the first mating surface 22 of the stack 12, for example using first bolts 24 which cooperate with threaded holes (not shown) in the stack 12. Similarly, second connection manifold 20 is also movable relative to the bracket 16, and is correspondingly removably connected to the cathode inlet side (not shown) of the first mating surface 22 of the stack 12, for example using second bolts 26 which cooperate with threaded holes (not shown) in the stack 12. Although fastening is shown in Figure 1 as being by way of bolts 24 and 26, one skilled in the art will appreciate that any suitable removable fastening method may be used.

[0033] As is shown in Figures 2A and 2B, in a particular embodiment the first connection manifold 18 has a generally planar second mating surface 28 having a plurality of apertures 30a to 30c defined therein. The apertures 30a to 30c are arranged to correspond to the process fluid inlet(s) (not shown) and process fluid outlet(s) (not shown) of the stack 12, so that a sealed fluid communication with the cell stack 12 process fluid inlets and outlets, respectively, is achieved when the first connection manifold 18 is attached to the stack 12. Anode process fluid inlet aperture 30a is connected in fluid communication with the corresponding process fluid outlet of the balance-of- plant 14 by way of anode process fluid inlet connector 32, and process fluid outlet apertures 30b (for coolant) and 30c (for the cathode) are connected in fluid communication with the corresponding process fluid inlet(s) of the balance-of-plant 14 by way of process fluid outlet connectors 34a (for coolant) and 34b (for the cathode). In turn, the anode process fluid inlet connector(s) 32 and the process fluid outlet connector(s) 34a and 34b are connected to process fluid conduits 44 from the balance-of-plant 14 of the system, as shown in Figure 1. Seals 36 are provided for sealing between the mating surfaces of the first connection manifold 18 and the stack 12 so that there is a sealing engagement therebetween. The seals 36 are preferably formed from a resilient material.

[0034] As is shown in Figures 3A and 3B, the second connection manifold 20 has a generally planar second mating surface 40. Apertures 42a, 42b and 42c are defined in the planar second mating surface 40. As with the first connection manifold 18, the apertures 42a, 42b and 42c are arranged to correspond to process fluid inlet apertures (not shown) and process fluid outlet apertures (not shown) of the stack 12, so that a sealed fluid communication with the process fluid inlets and outlets of the cell stack 12, is achieved when the second connection manifold 20 is attached to the stack 12. Similarly to the first connection manifold 18, process fluid inlet apertures 42a (for the cathode) and 42b (for coolant) are connected in fluid communication with the corresponding process fluid outlet(s) of the balance-of-plant 14 by way of process fluid inlet connectors 46a (for the cathode) and 46b (for coolant), and anode process fluid outlet aperture 42c is connectible in fluid communication with the corresponding process fluid inlet of the balance-of- plant 14 by way of process fluid outlet connector 48. In turn, the process fluid inlet connector(s) 46a (for the cathode) and 46b (for coolant) and the process fluid outlet connector 48 are connected to process fluid conduits 50 from the balance-of-plant 14 of the system 10, as shown in Figure 1. Again, seals 38 are provided for sealing between the second connection manifold 20 and the stack 12 so that there is a sealing engagement therebetween, and the seals 38 are preferably formed from a resilient material. [0035] It will be appreciated that while in the embodiment shown in

Figures 2A, 2B, 3A and 3B, the seals 36 and 38 are disposed on the connection manifolds 18, 20, the seals 36 and 38 may also be suitably disposed on the cell stack 12. Alternatively, some seals 36, 38 may be disposed on the cell stack 12 and other seals 36, 38 may be disposed on the connection manifolds 18 and 20. It will also be appreciated that the first connection manifold 18 and the second connection manifold 20 may be secured to one another, or may be combined into a single integral unit, without departing from the scope of the present invention. The particular configuration of the connection manifold(s) will of course depend on the configuration of the cell stack to which the balance-of-plant 14 is to be connected.

[0036] Advantageously, the first connection manifold 18 has at least one sensor 52 attached, for measuring at least one process parameter. The sensor can be a pressure transducer, a temperature sensor or a conductivity sensor, for example. The sensor(s) 52 are connected in electrical communication with a control system (not shown) for the balance-of-plant 14 or to a central regulation system (not shown), for regulating, diagnosing and monitoring the system, if desirable. Similarly, the second connection manifold 20 advantageously has at least one sensor 54, and preferably there is one sensor 52, 54, for each process fluid aperture.

[0037] The first connection manifold 18 further advantageously has a first water collection vessel 56 arranged at a lower end 58 of the first connection manifold 18 adjacent a process fluid inlet or outlet, for collecting excess water by gravity feed from one of the process fluid inlet 32 and/or outlets 34a or 34b. The water collection vessel 56 is preferably formed as an integral part of the first connection manifold 18, for example by forming a cavity inside the manifold 18. A first water purge connection 60 is arranged in fluid communication with the water collection vessel 56, so that collected water can be purged as necessary by opening, for example, a solenoid valve (not shown). [0038] Similarly, the second connection manifold 20 has a second water collection vessel 62 arranged at a lower end 64 of the second connection manifold 20 adjacent a process fluid inlet or outlet, for collecting excess water by gravity feed from one of the process fluid inlets 46a or 46b or outlet 48. As with the first connection manifold 18, the water collection vessel 62 is preferably formed as an integral part of the second connection manifold 20, for example by forming a cavity inside the manifold 20. A second water purge connection 66 is arranged in fluid communication with the water collection vessel 62, so that collected water can be purged as necessary. [0039] While the second mating surfaces 28 and 40 of the connection manifolds 18 and 20, and the first mating surface 22 of the cell stack 12, are shown in the instant embodiment as being planar surfaces, it will be appreciated that any suitable type of correspondingly shaped mating surfaces may be used. For example, the second mating surface(s) 28, 40 on the connection manifold(s) 18, 20 could comprise a curved protrusion, and the first mating surface 22 on the cell stack 12 could comprise a correspondingly- shaped curved channel that receives the curved protrusion to permit a sealing engagement when the cell stack 12 and the connection manifold(s) 18, 20 are pressed together. [0040] The bracket 16 may comprise two or more separate elements, such as a first bracket part permanently secured to the stack 12, and a second bracket part holding the balance of plant 12. The first and second bracket parts could bolted or clamped together, or fastened in any other suitable way, to sealingly connect the stack 12 to the first and second connection manifolds 18 and 20. When desired, the stack 12 could then be removed together with its respective first bracket part. Of course, the second bracket part, which holds the balance of plant 12, can also be removed separately if the jointed bracket concept is used. Because the first and second bracket parts would be movable relative to one another, the connection manifolds 18 and 20 would also be movable relative to the portion of the bracket 16 to which the cell stack 12 would be mounted. [0041] For illustrative purposes, Figure 4 shows a stack 12 having the first connection manifold 18 and the second connection manifold 20 connected thereto. On the first connection manifold 18, the anode process fluid inlet connector 32, process fluid outlet connectors 34b (for the cathode) and 34a (for coolant) and water collection vessel 56 are shown. Similarly, on the second connection manifold 20, the process fluid inlet connectors 46a (for the cathode) and 46b (for coolant), anode process fluid outlet connector 48 and water purge connector 66 are shown. One skilled in the art will recognize, of course, that the first connection manifold 18 and the second connection manifold 20 would be un-fastened from the stack 12 when the stack 12 is removed from the electrochemical cell system 10.

[0042] Now referring to Figures 5 to 7, an electrochemical cell system

100 is shown in combination with a second embodiment of a connection arrangement according to the present invention. Unlike in the first embodiment, in the second embodiment the stack 12 is mounted in a bracket 116 that substantially surrounds the stack 12 on four sides. The balance-of- plant retains the general reference number 14, although it is not collected in an area inside the bracket 16 of the first embodiment, but rather spread out around the bracket 116 of the second embodiment. The equipment comprising the balance-of-plant 14 is preferably fastened to the bracket 116 on all four sides of the bracket 116, excluding the top and bottom sides of the stack 12 (to facilitate removal of the stack 12 from the bracket). Similarly to the first embodiment, the second embodiment comprises a first connection manifold 118 and a second connection manifold 120. The connection manifolds 118 and 120 are advantageously connected to the stack 12 on separate sides of the stack 12, again to facilitate removal of the stack 12 from the bracket 116. A cover 105 is advantageously used to cover and protect the stack 12 (and/or the balance-of-plant 14) when the stack 12 is mounted to the bracket 116. The cover 105 is removably securable to either the stack 12 or the bracket 116. One skilled in the art will recognize, although this is not shown, that a similar cover may be used to protect the stack 12, or the entire fuel cell power module (FCPM, fuel cell stack and balance-of-plant as mounted to the bracket 16), in the first embodiment of the invention.

[0043] As can be seen with both the first embodiment 10 (Figures 1-3) and the second embodiment 100 (Figures 5 to 7) the configuration of the second mating surfaces 28 and 40 of the connection manifolds 18 and 20 (or

118 and 120), in this case generally planar, allows for the installation and removal of the cell stack 12 into and from the bracket 16 (or 116) with a minimum of clearance. Specifically, the clearance need only be enough to permit the first mating surface 22 of the cell stack 12 to slide along the second mating surfaces 28 and 40 (not shown) so that the cell stack 12 can be vertically inserted into and removed from the bracket 16 or 116.

[0044] In both the first and second embodiments, the connection manifolds 18 and 20 or 118 and 120 permit fluid communication paths between multiple process fluid inlets and/or outlets of the cell stack 12 and the corresponding process fluid inlets and/or outlets on the balance-of-plant 14 to be defined simultaneously by attachment of a single manifold 18, 20, 118, 120. Using the first embodiment as an example, connecting the first connection manifold 18 to the cell stack 12 simultaneously defines fluid communication paths between each of the anode process fluid inlet (via aperture 30a, cathode process fluid outlet (via aperture 30c) and coolant outlet (via aperture 30b), and the corresponding process fluid inlets and outlets on the balance-of-plant 14. Similarly, connecting the second connection manifold 18 to the cell stack 12 simultaneously defines fluid communication between each of the cathode process fluid inlet (via aperture 42a), the anode process fluid outlet (via aperture 42c) and the coolant inlet (via aperture 42b), and the corresponding process fluid inlets and outlets on the balance-of-plant 14. This facilitates rapid connection and disconnection of the stack 12 to and from the balance-of-plant 14.

[0045] When the stack 12 is attached to the balance-of-plant 14 using the first connection manifold 18 (or 118) and the second connection manifold

20 (or 120), the stack 12 can be easily removed from the bracket 16 (or 116) by unfastening the connection manifolds 18 and 20 (or 118 and 120), unfastening any connections to any hydrogen recirculation pump (if the stack is a fuel cell stack), unfastening the fastening means (not shown) holding the stack to the bracket 16 or 116, and then lifting the stack 12 vertically out of the bracket 16 116. This leaves all the process fluid conduit connections and all electrical connections to the respective sensors attached to the connection manifolds 18 and 20 (or 118 and 120). To install a new fuel cell stack 12, once the stack 12 has been slid into place within the bracket 16 (or 116), the stack 12 can be refastened to the bracket 16 (or 116) and connected to the hydrogen recirculation pump (not shown). The connection manifolds 18 and 20 (or 118 and 120) can then be fastened to the fuel cell stack 12, moving the connection manifolds 18 and 20 (or 118 and 120) towards the cell stack 12 and compressing them thereagainst so that the seals 36, 38 (not shown in Figure 1) are compressed, thereby sealingly connecting the apertures 30a-3c and 42a-40c in the connection manifolds 18 and 20 to the inlets and outlets in the cell stack 12 and creating a fluid communication path between the fuel cell stack 12 and the balance-of-plant 14.

[0046] As can be seen in both the first and second embodiments, the fact that the connection manifolds 18, 20 and 118, 120 are movable relative to the bracket 16, 116, permits one face of the cell stack 12 to be supported by the bracket 16, 116 while the process fluid connections are made to a different face (or faces) of the cell stack 12. In addition, as seen in Figures 5 to 7, making the connection manifolds 118, 120 movable relative to the bracket 16, 116 permits a configuration in which the connection manifolds 118, 120 are on opposed sides of the bracket.

[0047] The moveable coupling of the connection manifolds 18 and 20 or 118 and 120 can be achieved in any suitable manner. For example, flexible members may be secured between the connection manifolds 18 and 20 or 118 and 120 and the bracket 16 or 116. Alternatively, the fluid conduits connecting the connection manifolds 18 and 20 or 118 and 120 to the balance-of-plant 14 may be flexible so as to permit movement of the connection manifolds 18 and 20 or 118 and 120 relative to the bracket 16 or 116. Alternatively or additionally, the connection manifolds 18 and 20 or 118 and 120 may be movably mounted to the bracket 16 or 116, for example slidably mounted. [0048] Reference will now be made to Figures 8a and 8b, which show views of a further embodiment of the present invention, incorporating, manifolds for two adjacent fuel cell stacks. In effect, each manifold is a Siamese manifold that supplies the necessary fluids to both stacks.

[0049] A bracket is indicated at 136 and manifolds are shown on opposite sides of the bracket 136 at 138 and 140. The bracket 136 has side frames 142 and end frames 143, 144.

[0050] Various items of the balance-of-plant are mounted on the end frames 143, 144 and also on the side frames 142.

[0051] Full details of the bracket 136 are given in the assignee's copending application identified by attorney docket number 9351-452 and a title "Fuel Cell System and Bracket Therefore".

[0052] The pair of fuel cell stacks are indicated at 252, 253. As indicated at 254, the fuel cell stacks 252, 253 each include a group of ports on opposite sides of the stack. As shown, for each side frame 142, there is a group of ports 254 of one fuel cell stack 252 immediately adjacent a group of ports 254 of the other fuel cell stack 253. The side frames 142 include apertures, preferably rectangular apertures, providing access to these groups of ports 254.

[0053] Each manifold 138, 140 is shaped to correspond to the apertures in the side frames 142, so as to connect to the adjacent groups of ports 254, i.e. the manifolds are Siamese manifolds.

[0054] As for the manifolds 18, 20 described above, one of these

Siamese manifolds 138 corresponds to manifold 18 and the other of the Siamese manifolds 140 corresponds to manifold 20. [0055] Thus, manifold 138 includes, apertures in pairs for connection to the groups of ports: two anode process fluid inlet apertures; two process fluid outlet apertures for coolant; and two cathode process fluid outlet apertures. Each pair of the apertures is connected through the manifold 138 to a respective connector for connection to the corresponding inlet or outlet of the balance-of-plant.

[0056] Correspondingly, the second manifold 140 has, again, arranged in pairs for connection to appropriate ports of two adjacent groups of ports: a pair of apertures for a cathode process fluid inlet; a pair of anode process fluid outlet apertures; and a pair of coolant inlet apertures.

[0057] Thus, this arrangement provides a simple and compact manifold arrangement, enabling supply of the three process fluids (anode gas, cathode gas and coolant) to separate fuel cell stacks.

[0058] It is in general to be appreciated that while the various manifold configurations described above have indicated certain arrangements of the various flows, other combinations are possible. For example, there is no reason why the anode and cathode flows need always be in opposite directions. It is possible that a manifold could include inlet apertures for both the anode and cathode flows; another manifold would then be provided with apertures for the outlet flows for both the anode and cathode.

Correspondingly, there is not fixed correspondence between the inlet and outlet apertures for the coolant flow and the inlet and outlet apertures for the anode or cathode flows. For example, where a manifold has a pair of apertures for both the anode and cathode inlet flows, then an aperture for the coolant could be either for the coolant inlet or the coolant outlet, with the other manifold being correspondingly configured.

[0059] The invention recognizes that, in many fuel cell stack configurations, a pair of ports for any one process fluid flow will often be spaced apart, e.g. the pair of ports for an anode gas flow will usually be spaced apart, as will a pair of ports for the cathode flow and a pair of ports for the coolant flow. At the same time, ports are often arranged in groups where the ports are closely associated with one another. In each group of ports, there will then be a single port for an anode flow, a single port for the cathode flow and a single port for the coolant flow.

[0060] A manifold for connection to such a group of ports will then have just a single connection to an anode gas flow, i.e. connection for just one of the inlet or outlet gas flow. Correspondingly, there would be a single connection, to the balance-of-plant, for a cathode gas flow, and where applicable, the coolant flow. The number of apertures for connection to the fuel cell stack would then depend upon the particular configuration. Where the manifold is for connection to a single group of ports in one fuel cell stack, then there would be, correspondingly, a single aperture for each of the three flows. As detailed above in relation to Figures 8a and 8b, where a Siamese configuration is provided, then the apertures for mating and connection to the ports of the fuel cell stacks would be equal to the number of fuel cell stacks to be connected to that manifold. Figures 8a and 8b show an arrangement with two adjacent fuel cell stacks. It is possible that other configurations could provide full connection to a large number of fuel cell stacks.

[0061] Nonetheless, in accordance with the present invention, each manifold would still just handle, for each process fluid, either just the inlet flow or the outlet flow. The second manifold is then provided for handling the other of the inlet and outlet flows.

[0062] The precise amount of movement of the connection manifolds

18, 20 and 118, 120 relative to the bracket 16, 116 that is necessary will depend on the particular configuration; all that is required is that the connection manifolds 18, 20 or 118, 120 be capable of moving into and out of a sealing engagement with the fuel cell stack 12. Thus, in some cases movability on the order of millimeters may be sufficient.

[0063] While reference has been made herein to an exemplary embodiment in which the fuel cell stack 12 is mounted to a bracket 16 or 116, one skilled in the art will recognize that any suitable fuel cell stack support structure may be used to mount the balance-of-plant 14 and fuel cell stack 12. For example, the fuel cell stack support structure may be the chassis of a motor vehicle powered by fuel cells, or a portion of a building.

[0064] It should be understood that various modifications can be made, by those skilled in the art, to the preferred embodiments described and illustrated herein, without departing from the scope of the present invention, as defined by the appended claims. For example, when a coolant fluid is used as one of the process fluids, the manifold is also cooled by the fluid flowing through it. Alternatively, a separate manifold coolant may be used, although this is not shown in the figures. Additionally, depending on the configuration of the fuel cell stack to which they are to be attached, the connection manifolds may connect to different inlets and outlets on the fuel cell stack.

Claims

Claims:

1. A mounting structure for fuel cell stacks, comprising:

a fuel cell stack support structure, the fuel cell stack support structure having at least one receiving location in which at least one fuel cell stack can be removably mounted;

at least one fuel cell stack mounted to the fuel cell stack support structure;

a balance-of-plant, at least a portion of the balance-of-plant being mounted to the fuel cell stack support structure;

at least one connection manifold, the at least one connection manifold being connected in fluid communication with the balance-of-plant, and having at least one mating surface configured to matingly and sealingly engage at least one correspondingly configured mating surface on the least one fuel cell stack so as to define a plurality fluid communication paths between process fluid inlet and outlet parts of the at least one fuel cell stack and corresponding process fluid inlets and outlets of the balance-of-plant, the at least one connection manifold being movable relative to the fuel cell stack support structure and the at least one fuel cell stack.

2. The mounting structure of claim 1 wherein the at least one connection manifold comprises two connection manifolds.

3. The mounting structure of claim 2 wherein each of the two connection manifolds comprise a first connection manifold connectible in fluid communication with a first group of ports of one fuel cell stack, and a second connection manifold connectible in fluid communication with a second group of ports of said one fuel cell stack.

4. The mounting structure of claim 3, wherein each of the first and second groups of ports includes one anode port and one cathode port.

5. The mounting structure of claim 4, wherein each of the first and second groups of ports includes a coolant port.

6. The mounting structure of claim 1 wherein each connection manifold comprises a sensor for sensing a process parameter.

7. The mounting structure of claim 1 wherein each manifold comprises a water collection vessel disposed at a lower end thereof, and in fluid communication with a process fluid inlet or outlet.

8. The mounting structure of claim 1 wherein the at least one mating surface on the at least one connection manifold is generally planar.

9. The mounting structure of claim 1 wherein the at least one manifold is connected by flexible fluid conduits to the balance-of-plant.

10. The mounting structure of claim 3, wherein one of the manifolds includes an anode inlet aperture and a cathode outlet aperture and the other of the manifolds includes an anode outlet aperture and a cathode inlet aperture, and wherein each of the manifolds includes an aperture for a coolant flow.

11. A connection manifold for connection to a fuel cell stack, the manifold comprising:

one connector for connection to balance-of-plant for a first process gas flow and a corresponding first aperture in fluid communication with the first connector, for sealing engagement with a corresponding port with a fuel cell stack;

a second connector for connection to the balance-of-plant for a second process gas flow and a second aperture in fluid communication with the second connector and for sealing engagement with a corresponding port of a electrochemical cell stack; whereby, in use, to provide for both inflow and outflow of the first and second process gases, a pair of the manifolds at least are connected to the electrochemical cell stack.

12. The manifold as claimed in claim 11 , wherein the manifold includes a third connector for connection to the balance-of-plant for a coolant flow and a third aperture in fluid communication with the third connector and for sealing engagement with a corresponding port of the electrochemical cell stack, for the coolant flow.

13. The manifold as claimed in claim 12, wherein the manifold is adapted for connection to a first group of ports of one fuel cell stack and a second group of ports of at least one other fuel cell stack, wherein the first connector is in fluid communication with a pair of first apertures, the second connector is in fluid communication with a pair of second apertures and the third connector is in fluid communication with a pair of third apertures.

14. The manifold of claim 12, wherein the first, second and third apertures are substantially in line with one another and are provided on a common mating surface, and wherein the manifold is formed as an integral body.

15. The manifold as claimed in claim 12, which includes a sensor for each of the flows through the manifold.

16. The manifold as claimed in claim 12 or 15, which includes a water collection vessel provided at a lower end of the manifold and in communication with at least one of the first and second apertures for collection of excess moisture.

17. A manifold, for connection to an electrochemical cell, the manifold comprising:

at least two communication paths for at least two corresponding process fluid flows, each communication path including an aperture for sealing engagement with a port of the electrochemical cell and a connector for providing connection to the balance-of-plant for the respective process fluid flow; and

a water collection vessel provided below and in fluid communication with at least one of the process fluid paths, for collection of excess moisture.

18. The manifold as claimed in claim 17, including at least one sensor for each process fluid path.

19. The manifold as claimed in claim 18, including three process fluid paths, each including a respective aperture, a respective connector and a respective sensor.

20. An electrochemical cell stack, including two groups of spaced apart ports, wherein the electrochemical cell stack is adapted to have at least two process fluids flowing therethrough, with each process fluid having an inlet port in one group of ports and an outlet in the other group of ports, and wherein one manifold is provided for one group of ports and a separate, second manifold is provided for the other group of ports, each manifold including, for each process fluid flow, a connector for connection to balance- of-plant and an aperture in fluid communication with the corresponding connector and adapted for sealing engagement with the electrochemical cell stack.

21. The electrochemical cell stack of claim 20, wherein each group of ports includes a port for an anode gas flow, a port for a cathode flow and a coolant port.

22. The electrochemical cell stack of claim 21 , wherein each group of ports is provided on a substantially planar surface of the electrochemical cell, and each manifold includes a corresponding, planar mating surface including the connection apertures thereof.

23. The electrochemical cell stack as claimed in claim 20, wherein the two groups of ports are provided on the same side of the electrochemical cell stack and adjacent respective opposite edges of that side thereof.

24. The electrochemical cell stack as claimed in claim 20, wherein the group supports are provided on opposite sides of the electrochemical cell stack.