Abstract:
A fuel cell system enclosure having an integrated condenser and muffler is disclosed. The fuel cell enclosure includes a stack module having a stack module interior for containing a fuel cell stack, a humidifier provided in fluid communication with the stack module interior, and an integrated condenser/muffler provided in fluid communication with the stack module interior. A method for operating a fuel cell system having one or more fuel cells is also disclosed.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to fuel cells which are suitable for generating electricity for automotive or other applications. More particularly, the present invention relates to a fuel cell system enclosure having an integrated deionized water tank and condenser/muffler which reduces the plumbing requirements and enhances the package and weight efficiency and the thermal and noise insulation of the enclosure.  
       BACKGROUND OF THE INVENTION  
       [0002]     Recently, intensive research has been expended on the development of fuel cell systems to generate energy for automotive and other applications. A fuel cell system produces electricity by harvesting electrons from hydrogen gas. Oxygen is reduced by the electrons and combined with protons to produce water as a by-product. Fuel cell vehicles are highly efficient and environmentally-friendly.  
         [0003]     In a typical conventional fuel cell system, a fuel cell stack is contained in a stack module of a fuel cell enclosure. An air intake conduit distributes air through a humidifier and into the stack module, respectively, to humidify the air and distribute the humidified air into the stack module. The humidified air ensures that the membranes in the fuel cell stack remain sufficiently moist for optimum operation. An air exhaust conduit distributes exhaust air from the stack module and then through a condenser and a muffler, respectively. The condenser removes excess moisture from the exhaust air prior to entry of the exhaust air into the muffler. All or a portion of the recovered moisture is typically distributed from the condenser, through a DI (de-ionized) water tank and back to the humidifier to increase the moisture of the air before it enters the stack module.  
         [0004]     In the conventional fuel cell system, the condenser, the muffler and the DI water tank are separate elements. However, the design requires extra conduit to interconnect the condenser, muffler and DI water tank. Also, thermal and noise insulation of these elements are inefficient. Moreover, the design is inefficient from a packaging and weight distribution standpoint.  
         [0005]     Accordingly, a new and improved fuel cell enclosure is needed in which the condenser and muffler elements or the condenser, muffler and DI water tank elements are integrated into a single component.  
       SUMMARY OF THE INVENTION  
       [0006]     The present invention is generally directed to a novel fuel cell enclosure having an integrated condenser and muffler or an integrated condenser, muffler and DI water tank on the outlet side of a stack module which contains a fuel cell stack. In one embodiment of the invention, an air intake conduit is disposed in fluid communication with a stack module and a humidifier is provided in the air intake module. An air exhaust conduit extends from the stack module, and an integrated condenser/muffler is disposed in fluid communication with the air exhaust conduit. A DI water tank is connected to the integrated condenser/muffler through a connecting conduit. The integrated condenser/muffler imparts enhanced package and weight efficiency, as well as enhanced thermal and noise insulation, to the fuel cell stack.  
         [0007]     In another embodiment of the invention, the stack module includes a triple-walled stack module enclosure that contains a fuel cell stack. The stack module enclosure includes an integrated condenser/muffler and a DI water tank which surrounds the integrated condenser/muffler.  
         [0008]     In still another embodiment of the invention, the stack module includes a double-walled stack module enclosure which defines a stack module that contains a fuel cell stack. The double-walled stack module includes inner and outer walls that define a DI water tank that is adjacent to an integrated condenser/muffler. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     The invention will now be described, by way of example, with reference to the accompanying drawings, in which:  
         [0010]      FIG. 1  is a schematic view of a first embodiment of a fuel cell enclosure according to the present invention; and  
         [0011]      FIG. 2  is a schematic view of a second embodiment of a fuel cell enclosure according to the present invention; and  
         [0012]      FIG. 3  is a schematic view of a third embodiment of a fuel cell enclosure according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0013]     Referring initially to  FIG. 1  of the drawings, an illustrative embodiment of the fuel cell enclosure of the present invention is generally indicated by reference numeral  34 . The fuel cell enclosure  34  includes a stack module  36  which encloses a stack module interior  38 . A fuel cell stack (not shown) is contained in the stack module interior  38 .  
         [0014]     An integrated condenser/muffler  40  at least partially surrounds or encapsulates the stack module  36 . The integrated condenser/muffler  40  includes both a condenser (not shown) and a muffler (not shown). Coolant lines  41  typically distribute a liquid coolant (not shown) into and out of the integrated condenser/muffler  40 . A DI (de-ionized) water tank  44 , which contains a supply of DI (de-ionized) water (not shown), at least partially surrounds or encapsulates the integrated condenser/muffler  40 . An air exhaust conduit  50  establishes communication between the stack module  36  and the integrated condenser/muffler  40 . A water conduit  52  establishes fluid communication between the stack module  36  and the DI water tank  44  and extends through the integrated condenser/muffler  40 . An air discharge conduit  54  extends from the integrated/condenser muffler  40 , through the DI water tank  44 . A distribution conduit  58  establishes communication between the integrated condenser/muffler  40  and the DI water tank  44 .  
         [0015]     An air intake conduit  46  is disposed in fluid communication with the stack module interior  38  of the stack module  36  and extends through the integrated condenser/muffler  40  and DI water tank  44 . A humidifier  48 , which may be conventional, is provided in the air intake conduit  46 . A water return conduit  56  establishes fluid communication between the DI water tank  44  and the humidifier  48 .  
         [0016]     In operation of the fuel cell enclosure  34 , intake air  30   a  is distributed through the air intake conduit  46  and into the humidifier  48 . Moisture from the DI water tank  44  is added to the intake air  30   a , and the resulting humidified air  30   b  flows from the humidifier  48  and into the fuel cell stack (not shown) contained in the stack module interior  38  of the stack module  36 . As it passes through the fuel cell stack, the humidified air  30   b  maintains moisture of the polymer electrolyte membranes in the fuel cell stack, emerging from the stack as exhaust air  30   c.    
         [0017]     The exhaust air  30   c  is distributed from the fuel cell stack and stack module  36 , respectively, and into the integrated condenser/muffler  40  through the air exhaust conduit  50 . In the integrated condenser/muffler  40 , excess moisture is removed from the moisture-rich and oxygen-depleted exhaust air  30   c , forming dried air  30   d . The dried air  30   d  is discharged from the integrated condenser/muffler  40 , through the air discharge conduit  54  and into the atmosphere. The water  27  removed from the exhaust air  30   c  is distributed from the integrated condenser/muffler  40 , through the distribution conduit  58  and into the DI water tank  44 . This water  27  is distributed from the DI water tank  44 , through the water return conduit  56  and into the humidifier  48 . In the humidifier  48 , the water  27  combines with and imparts moisture to the intake air  30   a  and is then distributed into the stack module  36  as humidified air  30   b . Water  27   a  is distributed from the stack module  36 , through the water conduit  52  and directly into the DI water tank  44 .  
         [0018]     It will be appreciated by those skilled in the art that the compact design of the integrated condenser/muffler  40  of the fuel cell enclosure  34  imparts enhanced package and weight efficiency to the design of the fuel cell enclosure  34  as well as enhanced thermal and noise insulation to the fuel cell stack contained in the stack module  36 .  
         [0019]     Referring next to  FIG. 2  of the drawings, still another embodiment of the fuel cell enclosure of the present invention is generally indicated by reference numeral  60 . The fuel cell enclosure  60  includes a stack module  62  having a stack module interior  64  which contains a fuel cell stack (not shown). An integrated condenser/muffler  78  and a DI water tank  80 , which contains a supply of DI (de-ionized) water (not shown), at least partially surround or encapsulate the stack module  62  and are typically positioned in adjacent relationship to each other. Coolant lines  82  typically distribute a liquid coolant (not shown) into and out of the integrated condenser/muffler  78 . An air exhaust conduit  70  establishes fluid communication between the stack module  62  and the integrated condenser/muffler  78 . A water conduit  71  establishes communication between the stack module  62  and the DI water tank  80  to allow the passage of water  27   a  from the stack module  62  directly to the DI water tank  80 . A distribution conduit  72  establishes fluid communication between the integrated condenser/muffler  78  and the DI water tank  80 . An air discharge conduit  74  extends from the integrated condenser/muffler  78 .  
         [0020]     An air intake conduit  66  is disposed in fluid communication with the stack module interior  64  of the stack module  62 . A humidifier  68 , which may be conventional, is provided in the air intake conduit  66 . A water return conduit  76  establishes fluid communication between the DI water tank  80  and the humidifier  68 .  
         [0021]     In operation of the fuel cell enclosure  60 , intake air  30   a  is distributed through the air intake conduit  66  and into the humidifier  68 . Humidified air  30   b  flows from the humidifier  68  and into and through the fuel cell stack (not shown) in the stack module interior  64  of the stack module  62 . Exhaust air  30   c , which contains by-product water from the fuel cell stack, is distributed from the fuel cell stack.  
         [0022]     The exhaust air  30   c  is distributed from the stack module  62 , through the air exhaust conduit  70  and into the integrated condenser/muffler  78 . In the integrated condenser/muffler  78 , water  27  is removed from the moisture-rich and oxygen-depleted exhaust air  30   c  to form dried air  30   d . This dried air  30   d  is discharged from the integrated condenser/muffler  78 , through the air discharge conduit  74  and into the atmosphere. The water  27  is distributed from the integrated condenser/muffler  78 , through the distribution conduit  72  and into the DI water tank  80 .  
         [0023]     The water  27  is distributed from the DI water tank  80 , through the water return conduit  76  and into the humidifier  68 . In the humidifier  68 , the water  27  combines with and imparts moisture to the intake air  30   a  and is then distributed into the stack module  62  as humidified air  30   b , as was heretofore described. Water  27   a  is distributed directly from the stack module  62 , through the water conduit  71  and into the DI water tank  80 .  
         [0024]     Referring next to  FIG. 3  of the drawings, a third embodiment of the present invention is generally indicated by reference numeral  10 . The fuel cell enclosure  10  includes a stack module  12  having a stack module interior  14  which contains a fuel cell stack (not shown).  
         [0025]     An air intake conduit  16  is disposed in fluid communication with one side of the stack module  12 . A humidifier  18 , which may be conventional, is provided in the air intake conduit  16 . An air exhaust conduit  20  extends from the opposite side of the stack module  12 . An integrated condenser/muffler  22 , which includes both a condenser (not shown) and a muffler (not shown), is disposed in fluid communication with the outlet end of the air exhaust conduit  20 . Coolant lines  25  typically distribute a liquid coolant (not shown) into and out of the integrated condenser/muffler  22 .  
         [0026]     An air discharge conduit  24  extends from the integrated condenser/muffler  22 . A DI (de-ionized) water tank  26 , which contains a supply of DI (de-ionized) water  27 , is disposed in fluid communication with the integrated condenser/muffler  22  through a distribution conduit  32 . A water return conduit  28  connects the DI water tank  26  to the humidifier  18 .  
         [0027]     In operation of the fuel cell enclosure  10 , intake air  30   a  is distributed through the air intake conduit  16  and into the humidifier  18 , where moisture, typically from water  27  distributed from the DI water tank  26 , as will be hereinafter described, is added to the intake air  30   a . Humidified air  30   b  flows from the humidifier  18  and into the fuel cell stack (not shown) in the stack module interior  14  of the stack module  12 . As it passes through the fuel cell stack, the humidified air  30   b  maintains the polymer electrolyte membranes at a moisture level which is sufficient to ensure optimum operation of the fuel cell stack. The resulting moisture-rich and oxygen-depleted exhaust air  30   c  is distributed from the stack module  12 , through the air exhaust conduit  20  and into the integrated condenser/muffler  22 .  
         [0028]     As the exhaust air  30   c  passes through the integrated condenser/muffler  22 , the condenser removes excess water  27  from the exhaust air  30   c , forming dried air  30   d . The dried air  30   d  is discharged from the integrated condenser/muffler  22 , through the air discharge conduit  24  and into the atmosphere. The water  27  removed from the exhaust air  30   c  flows from the integrated condenser/muffler  22 , through the distribution conduit  32  and into the DI water tank  26 .  
         [0029]     The water  27  discharged from the condenser/muffler  22  through the distribution conduit  32  collects in the DI water tank  26 . The water  27  is distributed from the DI water tank  26 , through the water return conduit  28  and to the humidifier  18 , respectively. This can be carried out in any of various ways. For example, a pump (not shown) may be provided in the water return conduit  28 , in which case the water  27  can be pumped from the DI water tank  26  to the humidifier  18 . Alternatively, the water  27  can be pushed from the DI water tank  26  to the humidifier  18  using the pressure of the exhaust air  30   c  in the condenser/muffler  22 , in combination with gravity. Still further in the alternative, in the case of a gas-to-gas humidifier  18 , the air discharge conduit  24  may be connected to the humidifier  18  to supply partially-dried air to the humidifier  18 . In that case, the water  27  collected from the condenser/muffler  22  would simply be removed through the distribution conduit  32 . In the humidifier  18 , the water  27  is combined with the intake air  30   a  to impart moisture to the intake air  30   a , and is then distributed into the stack module  12  as humidified air  30   b.    
         [0030]     It will be appreciated by those skilled in the art that the integrated condenser/muffler  22  is characterized by enhanced space, weight and cost efficiency compared to the conventional separate condensers and mufflers.  
         [0031]     While the preferred embodiments of the invention have been described above, it will be recognized and understood that various modifications can be made in the invention and the appended claims are intended to cover all such modifications which may fall within the spirit and scope of the invention.