Abstract:
A manifold for a fuel cell system, has a manifold body and a plurality of first ports in the manifold body, for connecting to fuel cell peripherals. A plurality of second ports in the manifold body provide connections to a fuel cell. A plurality of first fluid passages within the manifold provide communication between respective ones of the first ports and respective ones of the second ports, whereby, in use, the fluid passages communicate fluids between the fuel cell stack and fuel cell peripherals. The manifold provides a higher degree of system integration, considerably reduced piping, fittings and associated hardware and hence generally reduces the size and weight of the fuel cell system. Thermal-fluid related system losses are also minimized.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates to a manifold for a fuel cell system, and more particularly relates to a manifold for mounting peripherals and piping to fuel cell stacks.  
         BACKGROUND OF THE INVENTION  
         [0002]    Fuel cells have been proposed as a clean, efficient and environmentally friendly source of power which can be utilized for various applications. A fuel cell is an electrochemical device that produces an electromotive force by bringing the fuel (typically hydrogen) and an oxidant (typically air) into contact with two suitable electrodes and an electrolyte. A fuel, such as hydrogen gas, for example, is introduced at a first electrode, i.e. anode where it reacts electrochemically in the presence of the electrolyte to produce electrons and cations. The electrons are conducted from the anode to a second electrode, i.e. cathode through an electrical circuit connected between the electrodes. Cations pass through the electrolyte to the cathode. Simultaneously, an oxidant, such as oxygen gas or air is introduced to the cathode where the oxidant reacts electrochemically in presence of the electrolyte and catalyst, producing anions and consuming the electrons circulated through the electrical circuit; the cations are consumed at the second electrode. The anions formed at the second electrode or cathode react with the cations to form a reaction product. The anode may alternatively be referred to as a fuel or oxidizing electrode, and the cathode may alternatively be referred to as an oxidant or reducing electrode. The half-cell reactions at the two electrodes are, respectively, as follows:  
           H2 — 2H++2e− 
           ½O 2 +2H++2e−_H 2 O  
           [0003]    The external electrical circuit withdraws electrical current and thus receives elecl:rical power from the fuel cell. The overall fuel cell reaction produces electrical energy as shown by the sum of the separate half-cell reactions written above. Water and heat are typical by-products of the reaction. Accordingly, the use of fuel cells in power generation offers potential environmental benefits compared with power generation from combustion of fossil fuels or by nuclear activity. Some examples of applications are distributed residential power generation and automotive power systems to reduce emission levels.  
           [0004]    In practice, fuel cells are not operated as single units. Rather fuel cells are connected in series, stacked one on top of the other, or placed side-by-side, to form what is usually referred to as a fuel cell stack. The fuel, oxidant and coolant are supplied through respective delivery subsystems to the fuel cell stack. Also within the stack are current collectors, cell-to-cell seals and insulation, with required piping and instrumentation provided externally to the fuel cell stack.  
           [0005]    In conventional fuel cell systems, extensive piping and plumbing work is required since in operation fuel cell systems rely on peripheral preconditioning devices for optimum or even proper operation. 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 the membrane requires 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.  
           [0006]    These peripheral devices require extensive piping and associated hardware, all of which leads to poor system efficiency. This results from significant energy losses occurring in lines or conduits as more power must be made available for supplementary devices such as pumps, fans, saturators etc, and hence the parasitic load is increased. In addition, hoses, pipes, valves, switches and other fittings increase the overall weight and size of the fuel cell system and complicate the commercial application thereof. This complexity poses problems in many applications, such as vehicular applications, where it is desirable that the piping and weight of the fuel cell system be minimized since strict size constraints exist. Furthermore, in vehicular applications, it is desirable for the fuel cell system to have good transient thermo-fluid response characteristics. This requirement makes it even more difficult to apply conventional fuel cell systems to vehicular applications, where relatively long pathways through hoses, valves, etc., can prevent rapid transient response characteristics being obtained.  
           [0007]    Various efforts have been made to simplify the piping of fuel cell systems and hence reduce the size and weight thereof. However, to the applicants&#39; knowledge, there has yet to be disclosed any fuel cell system that solves this fundamental problem.  
         SUMMARY OF THE INVENTION  
         [0008]    In accordance with a first aspect of the present invention, there is provided a manifold for a fuel cell system, comprising: a manifold body; a plurality of first ports in the manifold body, for connecting to fuel cell peripherals; a plurality of second ports in the manifold body, for connecting to a fuel cell; and a plurality of first fluid passages within the manifold providing communication between respective ones of the first ports and respective ones of the second ports, whereby, in use, the fluid passages communicate fluids between the fuel cell stack and fuel cell peripherals.  
           [0009]    Preferably, the manifold body comprises a single plate with the first ports and second ports are provided such that when the fuel cell and fuel cell peripherals are mounted onto the manifold, the first and second ports are adjacent inlets and outlets of fuel cell and fuel cell peripherals.  
           [0010]    More preferably, at least one of the anode inlet port and cathode inlet port has a water separation chamber formed within the manifold body so that water in at least one of the reactant streams of the fuel cell is collected in the water separation chamber.  
           [0011]    More preferably, the manifold body further comprises a plurality of third ports and a plurality of second fluid passages within the manifold body in communication with the third ports and first fluid passages, and wherein said third ports and second fluid passages are adapted to accommodate monitoring devices to monitor fluid condition.  
           [0012]    According to another aspect of the invention, there is provided a fuel cell system comprising a fuel cell, including: at least one fuel cell having a cathode inlet and a cathode outlet for an oxide, an anode inlet and an anode outlet for a fuel, and a coolant inlet and a coolant outlet; a manifold having ports connected to the cathode inlet, the cathode outlet, the anode inlet, the anode outlet, the coolant inlet, and the coolant outlet of the fuel cell stack; a plurality of additional ports including at least a port for an oxidant inlet, a port for a fuel inlet, and inlet and outlet ports for the coolant; and a plurality of peripheral devices connected to the additional ports of the manifold.  
           [0013]    Preferably, the peripheral devices include first enthalpy shifting device, wherein the oxidant inlet is connected by the manifold through the first enthalpy shifting device to the cathode inlet of the fuel cell.  
           [0014]    More preferably, the peripheral devices further include a second enthalpy shifting device, and wherein the fuel inlet is connected by the manifold through the second enthalpy shifting device to the anode inlet of the fuel cell, and wherein the manifold includes a fuel outlet port and a connection between the anode outlet and the fuel outlet port.  
           [0015]    More preferably, the manifold provides a recirculation passage between the cathode outlet of the fuel cell and one of the first and second enthalpy shifting devices.  
           [0016]    More preferably, the fuel cell comprises at least one fuel cell stack disposed between an end plate and the manifold.  
           [0017]    The manifold according to the present invention provides an interface between the fuel cell stack and heat exchangers, pump, fans, compressors, reformers, humidifiers etc, as well as process gases and coolant delivery components. This configuration can provide a higher degree of system integration, and hence offers a number of advantages. First, flow channels embossed into the manifold eliminate the need for bulky hoses and fittings and therefore the size and weight of the fuel cell system is considerably reduced. Moreover, thermodynamic and fluid flow related losses in the system are reduced, thus improving system efficiency, response to transient conditions and system control. In addition, since piping is minimized, control and maintenance of the system is simplified. Utilizing the invention minimizes all of the aforementioned difficulties because the compact nature of the manifold allows fuel cell systems to be developed for applications where strict size and weight constraints exist.  
           [0018]    Fuel cell systems incorporating the present invention are inherently modular, and thus can be easily reproduced in large quantities at dedicated production facilities. Furthermore, the manifold of the present invention can be manufactured using currently available, inexpensive materials, which makes it suitable for manufacturing and mass production. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]    For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made to the accompanying drawings, which show, by way of example, preferred embodiments of the present invention. The features and advantages of the present invention will become more apparent in light of the following detailed description of preferred embodiments thereof.  
         [0020]    [0020]FIG. 1 is a perspective view illustrating a manifold for a fuel cell system according to the present invention;  
         [0021]    [0021]FIG. 2 is a perspective view from another angle illustrating the manifold for a fuel cell system according to the present invention;  
         [0022]    [0022]FIG. 3 is a schematic process flow diagram illustrating an application of the manifold for a fuel cell system according to the present invention;  
         [0023]    [0023]FIG. 4 is a perspective view illustrating the manifold for a fuel cell system in a fuel cell power unit;  
         [0024]    [0024]FIG. 5 is a front elevation view of the manifold for a fuel cell system according to the present invention, in which devices assembled onto the manifold are shown;  
         [0025]    [0025]FIG. 6 is front elevation view of the manifold for a fuel cell system according to the present invention;  
         [0026]    [0026]FIG. 7 is a sectional view of the manifold for a fuel cell system according to the present invention, taken along line A-A in FIG. 6;  
         [0027]    [0027]FIG. 8 is a sectional view of the manifold for a fuel cell system according to the present invention, taken along line B-B in FIG. 6;  
         [0028]    [0028]FIG. 9 is a sectional view of the manifold for a fuel cell system according to the present invention, taken along line C-C in FIG. 6;  
         [0029]    [0029]FIG. 10 is a sectional view of the manifold for a fuel cell system according to the present invention, taken along line D-D in FIG. 6;  
         [0030]    [0030]FIG. 11 is a sectional view of the manifold for a fuel cell system according to the present invention, taken along line E-E in FIG. 6;  
         [0031]    [0031]FIG. 12 is a sectional view of the manifold for a fuel cell system according to the present invention, taken along line F-F in FIG. 6.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0032]    Now referring to FIGS. 1 and 2, in which a manifold  10  according to the present invention is shown, the manifold  10  generally comprises one single plate having a plurality of ports and fluid passages provided on the side faces and internally.  
         [0033]    [0033]FIG. 3 shows a process flow diagram illustrating the application of the manifold  10  of the present invention in a fuel cell system comprising a fuel cell stack  12 . The fuel cell stack  12  typically has three inlets and three outlets, specifically, an anode inlet  103  for fuel gas, typically hydrogen, an anode outlet  104  for the fuel gas, a cathode inlet  101  for oxidant gas, typically oxygen or air, a cathode outlet  102  for oxidant gas, a coolant inlet  105  and a coolant outlet  106 . It should be appreciated that the fuel cells in the fuel cell stack can be any type of fuel cell, such as, proton exchange membrane fuel cells, solid oxide fuel cells, direct methanol fuel cells, etc. The type of the fuel cells will not affect the design of the manifold according to the present invention.  
         [0034]    Now the process flow of the fuel cell system will be described in detail with reference being made to FIGS.  3  to  5 . Fuel, such as hydrogen, supplied from a fuel source, passes through an anode humidifier  90  (an enthalpy shifting device) upstream of the anode inlet  103  for heating and humidifying the anode inlet stream of the fuel cell stack  12 . Then the humidified anode inlet stream flow through an anode inlet water separator  95  in which excess liquid water in the anode inlet stream is separated. Then, the anode inlet stream flows into the fuel cell stack  12  through the anode inlet  103 . In known manner, a number of monitoring devices are provided immediately upstream of the anode inlet  103 , such temperature sensor and pressure transmitter, etc, for monitoring the condition of the anode inlet stream.  
         [0035]    In FIGS. 5 and 6, hydrogen passes through the anode humidifier  90  and flows along a conduit (not shown) that connects the one outlet of humidifier  90  mounted on one side of the manifold  10  to the anode inlet port  1  on the manifold plate. Port  1  is a through hole through the thickness of the manifold  10 , as shown FIG. 7, and in communication with anode inlet  103  of the fuel cell stack on the opposite side of the manifold plate  10 . It is positioned corresponding to the anode inlet  103  of the fuel cell stack  12 . As shown in FIGS. 6, 7,  9  and  11 , an internal passage  201  fluidly connects the anode inlet port  1  and left side (as in FIG. 6) of the manifold  10  and a through hole  202  is provided in fluid communication with passage  201  and extending substantially perpendicular to the plane of FIG. 6. Monitoring devices can be placed in the through hole  202  from both sides (front and rear in FIG. 6) of the manifold  10  to measure parameters of the anode inlet fluid immediately upstream of the anode inlet  103 , providing accurate information of the anode inlet stream. A plug  203  can be provided to close the internal passage  201  in operation, if this is not otherwise required. It is also known that plugs can be provided to close one or both ends of the through hole  202  if necessary, for example, when only one pressure transmitter is inserted from one side of the manifold.  
         [0036]    A water separation chamber  204  is provided internally within the manifold  10  in communication with the anode inlet port  1 . The water separation chamber  204  serves the function of the anode outlet water separator  95  in FIG. 3, and compresses a chamber extending vertically down from anode inlet port  1 . The separation chamber  204  also has a relatively large flow cross-section, as compared to the anode inlet  1 , to promote lower velocities and separation of water from the fuel gas. As noted below, it is usually preferred to insert a water separation device in the chamber  204 . An internal drain passage  206  is provided on the left side (FIG. 6) of the manifold  10  and in communication with the bottom portion of the water separation chamber  204  to discharge separated water out of the manifold  10 . An internal passage  205  is provided above the drain passage  206  and a water level switch can be placed into the passage  205  to monitor the level of the separated water so that the water can be discharged, e.g. by pumping if required, on a regular basis. It is to be understood that a water separation device can be disposed in the water separation chamber  204  to enhance separation of liquid water from the anode inlet stream. The water separation device can be any commonly used device customized to fit into the chamber  204 .  
         [0037]    Fuel (hydrogen) stream flows through the fuel cell stack  12  and leaves the fuel cell stack  12  through the anode outlet  104 . The manifold  10  has an anode outlet port  6  positioned corresponding to the anode outlet  104  of the fuel cell stack  12 . The anode outlet port  6  is not a through hole through the thickness of the manifold  10  as is the anode inlet port  1 . The outlet port  6  is a blind hole starting from the rear side (FIGS. 6 and 8) of the manifold  10 . The fuel exhaust passes into the anode outlet port  6  and leaves the manifold  10  via an internal passage  207  that communicates the anode outlet port  6  with right side (FIG. 6) of the manifold  10 . A monitoring device can be placed in a passage  211  (FIG. 12) that extends from the rear side of the manifold  10  and communicates with the passage  207 , to monitor the condition of fuel exhaust stream. As shown in FIGS. 6 and 8, an internal water drain passage  208  extending from the bottom face of the manifold  10  is in communication with the anode outlet port  6  and another internal water drain passage  210  communicates the drain passage  208  with the right side of the manifold  10 . Liquid water from the anode exhaust stream can be directed out of the manifold  10  via the two drain passages  208  and  210 . It will be appreciated that a plug  209  is used to close the drain line  208  on the bottom face of the manifold  10 .  
         [0038]    As shown in FIG. 3, a portion of the fuel exhaust is recycled to the anode inlet  103  of the fuel cell stack  12 . This can be done by a conduit (not shown) that communicates the passage  207  with the anode inlet port  1  outside of the manifold  10 . Since the manifold  10  is compact, the length of this recycling conduit is short and loss of heat and humidity in the fuel exhaust is thus considerably reduced.  
         [0039]    As shown in FIG. 3, oxidant, such as air, is supplied from ambient by, for example, an air blower  35  or compressor, to pass through an enthalpy shifting device, e.g. an enthalpy wheel  80  for heating and humidifying the cathode inlet stream. Then the cathode inlet stream passes through a cathode inlet water separator  85  immediately upstream of the cathode inlet  101  of the fuel cells stack  12 . In FIG. 6, the air is supplied to an internal passage  330  that extends substantially horizontally from the right side (FIG. 6) of the manifold  10  to a position inside the manifold  10  adjacent an inlet of cathode inlet stream in the enthalpy wheel  80 . A blind hole  331  extending from the front side of the manifold  10  communicates the internal passage  330  with the front face of the manifold  10  and a conduit (not shown) connects the blind hole  331  with the inlet of the enthalpy wheel  80 . Then air flows along the passage  330 , the blind hole  331  and the conduit to an inlet  80   a  of the enthalpy wheel  80  and flows through the enthalpy wheel  80  from the left to the right side. Then, the air stream flows along a conduit (not shown) that connects an outlet  80   b  of the enthalpy wheel  80  to a cathode inlet port  4  of the manifold  10 . The cathode inlet port  4  is a through hole through the thickness of the manifold  10  and positioned corresponding to the anode inlet  101  of the fuel cell stack  12 .  
         [0040]    It will be appreciated that it is preferably to provide ports on manifold  10  adjacent the inlets and outlets of the enthalpy wheel  80  and anode humidifier  90  and other fuel cell peripherals so that the length of the conduits used to connect the ports of the manifold  10  and the fuel cell peripherals is minimized to reduce heat and pressure loss in conduits. Since manifold  10  can be manufactured using materials having good heat insulation property, the heat loss within the manifold  10  can be much lower than that in conduits outside of the manifold  10 .  
         [0041]    As shown in FIGS. 6, 7,  8  and  12 , an internal passage  301  fluidly connects the anode inlet port  1  to the right side (as in FIG. 6) of the manifold  10  and a through hole  302  is provided in fluid communication with passage  301  and extending substantially perpendicularly to the plane of FIG. 6. Monitoring devices can be placed in the through hole  302  from one or both sides (front and rear in FIG. 6) of the manifold  10  to measure parameters of the cathode inlet fluid immediately upstream of the cathode inlet  101 , providing accurate information of the cathode inlet stream. A plug  303  can be provided to close the internal passage  301  in operation. It is also known that plugs can be provided to close one or both ends of the through hole  302  if necessary, for example, when only one pressure transmitter is inserted from one side of the manifold. Corresponding to the water separation chamber  204 , a water separation chamber  304  is provided internally of the manifold  10  in communication with the cathode inlet port  6 . The water separation chamber  304  serves the function of the cathode inlet water separator  85  in FIG. 3. An internal drain passage  306  is provided on the right side (FIG. 6) of the manifold  10  and in communication with the bottom portion of the water separation chamber  304  to discharge separated water out of the manifold  10 . An internal passage  305  is provided above the drain passage  306  and a water level switch can be placed into the passage  305  to monitor the level of the separated water so that the water can be discharged, e.g. by pumping if required, on a regular basis. It is to be understood that a water separation device can be disposed in the water separation chamber  304  to enhance separation of liquid water from the cathode inlet stream as for the chamber  204 . The water separation device can be any commonly used device customized to fit into the chamber  304 .  
         [0042]    As shown in FIG. 3, an oxidant (air) stream flows through the fuel cell stack  12  and leaves the fuel cell stack  12  through the cathode outlet  102 . The cathode exhaust stream is recirculated from the cathode outlet  102  of the fuel cells stack  12  to the anode humidifier  90  and then to the enthalpy wheel  80 . The humidity and heat in the cathode exhaust stream is transferred to the incoming fuel stream in the anode humidifier  90  and the incoming oxidant stream in the enthalpy wheel  80 , respectively. Then the cathode exhaust is discharged to the environment.  
         [0043]    The manifold  10  has a cathode outlet port  3  positioned corresponding to the cathode outlet  102  of the fuel cell stack  12 . The cathode outlet port  3  is not a through hole through the thickness of the manifold  10  as is cathode inlet port  4 . It is a blind hole extending from the rear side (FIG. 6) of the manifold  10 . The oxidant exhaust passes through the cathode outlet port  3  and flows along an internal flow passage  350  extending substantially horizontally from left side of the manifold  10  to a position inside of the manifold  10  from where another internal passage  351  starts to extend upwardly to the top surface of the manifold  10 . A blind hole  352 , extending from the front face of the manifold  10  and extending substantially perpendicular to the plane of FIG. 6, intercepts and communicates with the passage  350 . The blind hole  352  is position such that it is adjacent to the inlet for cathode exhaust on the anode humidifier  90 . A conduit (not shown) connects the blind hole  352  to the said inlet. Therefore, cathode exhaust stream flows from cathode outlet port  3 , along passages  350 ,  351 ,  352  and the conduit (not shown) into the anode humidifier  90 . Then the cathode exhaust flows through the anode humidifier  90  to the enthalpy wheel  80  via a conduit (not shown) connecting an outlet of the anode humidifier  90  to an inlet  80   c  of the enthalpy wheel  80 . The cathode exhaust stream is discharged after it passes through the enthalpy wheel  80  through an outlet  80   d . As shown in FIG. 6, an internal water drain passage  308  extending from the bottom face of the manifold  10  and is in communication with the cathode outlet port  3  and another internal water drain passage  310  communicates the drain passage  308  with the left side of the manifold  10 . Liquid water from the cathode exhaust stream can be directed out of the manifold  10  via the two drain passages  308  and  310  immediately after it comes out of the fuel cell stack  12 . It will be appreciated that a plug  309  is used to close the drain line  208  on the bottom face of the manifold  10 . It will also be understood that monitoring devices, such as a pressure transmitter, a temperature sensor can be placed in a passage  353  in communication with the passage  350  to monitor the condition of cathode exhaust stream. The passage  353  extends from the rear side (FIG. 6) of the manifold  10 , i.e. the side on which the fuel cell stack  12  is mounted as can be best seen in FIG. 11.  
         [0044]    As shown in FIG. 3, a cooling loop  14  is provided for the fuel cell stack  12  in which coolant is continuously circulated to pass through the fuel cell stack  12 , and hence to absorb the heat generated in fuel cell reaction. In FIG. 6, a coolant inlet port  5  and a coolant outlet port  2  are provided corresponding to the coolant inlet  105  and coolant outlet  106  of the fuel cell stack  12 , respectively. Coolant inlet port  5  is a through hole extending through the entire thickness of the manifold  10  while coolant outlet port  2  is a blind hole extending from the rear side (FIG. 6) of the manifold  10 . Coolant is supplied to the coolant inlet port  5  on the front face of the manifold  10  and flows through the coolant inlet port  5  into the coolant inlet  105 . An internal passage  401  fluidly connects the coolant inlet port  5  with right side of the manifold  10 . Monitoring devices can be placed in a through hole  402 , connected to the passage  401 , to monitor the condition of the coolant adjacent the coolant inlet  105 . The through hole  402  extends through the thickness of the manifold  10 . In case a compressor is used, coolant may be directed to cool the compressed air immediately after the air exits from the compressor to prevent the overheating of enthalpy wheel  80 . Therefore, a portion of the coolant is directed along the passage  401  to a heat exchanger for cooling the incoming air. When such cooling is not necessary, such as when incoming air is under ambient pressure, the passage  401  can simply be closed by a plug.  
         [0045]    The coolant flows through the fuel cell stack  12  and leaves the fuel cell stack  12  through the coolant outlet  106 . Then the coolant continues to flow to the coolant outlet port  2  and leaves the manifold  10  via an internal passage  403  that fluidly connects the left side (FIG. 6) of the manifold to the coolant outlet  2 . Then coolant returns to the coolant storage tank  11  as shown in FIG. 3 via, for example a conduit (not shown). A through hole  404  is provided to intercept the passage  403  and monitoring devices can be placed in the through hole  404  to monitor the condition of the coolant adjacent the coolant outlet  106 .  
         [0046]    Preferably, as shown in FIG. 6, an internal water drain passage  250  is provided extending substantially horizontally. Water separated from the drain passages  206  and  306  is directed to the passage  250 . Specifically, the drain passage extends from left side to right side of the manifold  10  and two blind holes  260  and  360  extending from the front face intercept the drain passage  250 . A pair of mounting holes  261  are provided adjacent the blind hole  260  and similarly a pair of mounting holes  362  are provided adjacent the blind hole  360  for respectively mounting on the front face of the manifold  10  a connector  270  (FIG. 5) fluidly communicating with the blind hole  260  and a connector  370  (FIG. 5) fluidly communicating with the blind hole  360  Water separated from drain passage  206  is directed via a conduit (not shown) to the connector and to the drain passage  250  through the blind hole  260 . Likewise, water separated from drain passage  306  is directed via a conduit (not shown) to the other connector and to the drain passage  250  through the blind hole  360 . Then the collected water in drain passage  250  can be directed out of the manifold from either end of the drain passage  250 . It will be appreciated that the other end is closed by, for example, a plug.  
         [0047]    As can be appreciated from the above description, the fuel cell stack  12  is mounted on the rear side (FIG. 6) of the manifold  10 , i.e. below the plane of FIG. 6. The manifold  10  has a plurality of through holes  500  so that securing means, such as bolts can be accommodated in the through holes  500  to secure the fuel cell stack  12  onto the manifold plate  10 . It will also be appreciated from FIG. 6 that mounting holes  501  are provided for mounting the anode humidifier  90  and mounting holes  502  are provided for mounting the enthalpy wheel  80 . Generally, the fuel cell stack  12  has two end plates and clamping means to hold together the stack of individual fuel cells within the fuel cell stack  12 . End plates of the fuel cell stack  12  have various ports for fuel, oxidant and coolant. In the present invention, the fuel cell stack may also have such end plates and when assembled with the manifold plate, one end plate abuts against one side (rear side in FIG. 6) of the manifold  10 . However, it is apparent from the above description that the manifold  10  of the present invention can simply be used as an end plate of the fuel cell stack  12 . In this case, the size of the overall system is further reduced, and seals can be eliminated.  
         [0048]    It is to be understood that although not deliberately described, conventional sealing and clamping devices, such as O-rings are utilized around each connection of conduits, ports and passages. It will be appreciated that the plurality of ports and fluid passages described can be formed by etching or milling while the ports can be formed by boring or drilling. The manifold in the present invention can be manufactured with readily available, cheap materials with adequate heat durability or fluid resistance, including but not limited to polymers, Nylon, etc. Preferably, the material should have light weight. Also, the manifold could be formed by molding, which for at least some of the ducts would eliminate the need for holes or passages closed at one end by a plug.  
         [0049]    It is also possible that other fuel cell peripherals, such as the enthalpy wheel, DC/AC converter, etc can be coupled to the manifold  10 . The arrangement of ports and fluid passages may be varied in accordance with the particular process. The manifold  10  can also be manufactured in L shape, arc shape, triangle shape, etc. Additionally, one or more peripheral components can be mounted to the same face of the manifold or the fuel cell stack. While the invention has been described with one manifold mounted to one fuel cell stack, other combinations are possible. For example, one manifold could be provided for a number of stack assemblies, to enable sharing of peripheral components. On the other hand, one (or more than one) fuel cell stacks could have two or more manifolds; for example, a common stack configuration provides connection ports on both ends, and it may be advantageous to provide a manifold at each end, which manifolds may have different configurations.  
         [0050]    It is to be noted that various fluid passages within the manifold  10  can be provided either internal of the manifold or on the surface thereof in the form of open channels, depending on the configuration of the fuel cell system.  
         [0051]    It should be appreciated that the spirit of the present invention is concerned with a novel structure of the manifold for fuel cell systems and its use as an interface between the fuel cell stack and the peripherals. The type and internal structure of the fuel cell stack does not affect the design of the present invention. In other words, the present invention is applicable to various types of fuel cells, electrolyzers or other electrochemical cells. The position, number, size and pattern of those ports provided on the manifold assembly are not necessarily identical as disclosed herein.  
         [0052]    It is anticipated that those having ordinary skill in this art can make various modification to the embodiment disclosed herein after learning the teaching of the present invention. For example, the shape of the manifold assembly, the number or arrangement of ports might be different, the materials for making the manifold assembly might be different and the manifold assembly might be manufactured using different methods as disclosed herein. However, these modifications should be considered to fall under the protection scope of the invention as defined in the following claims.