JP5498835B2 - Fuel cell system - Google Patents

Description

  The present invention includes a fuel cell stack including a power generation cell in which an electrolyte / electrode structure having a pair of electrodes disposed on both sides of an electrolyte and a separator are stacked, and a reactive gas supply that circulates and supplies a reactive gas to the fuel cell stack The present invention relates to a fuel cell system including the apparatus.

  For example, in a polymer electrolyte fuel cell, an electrolyte membrane / electrode structure (an electrolyte / electrode structure) in which an anode electrode and a cathode electrode are disposed on both sides of an electrolyte membrane (electrolyte) made of a polymer ion exchange membrane, respectively. ) (MEA) is provided with a unit cell (power generation cell) sandwiched between separators.

  This type of fuel cell is usually used as a fuel cell stack in which a predetermined number (for example, several tens to several hundreds) of unit cells are stacked in order to obtain a desired power generation when used for in-vehicle use. Yes. In that case, the fuel cell stack generally includes a reaction gas flow channel for flowing a reaction gas along the electrode surface in the plane of the separator, and a reaction communicating with the reaction gas flow channel and penetrating in the stacking direction of the unit cells. A so-called internal manifold having a gas communication hole is employed.

  In a fuel cell stack, an ejector is used to circulate and supply a reaction gas, for example, a fuel gas, which is discharged without being used for the reaction, into a new fuel gas and supply it to the fuel gas passage (reaction gas passage). Has been. This is because the fuel gas can be used efficiently and economically by reusing unused fuel gas.

  For example, in the fuel cell system disclosed in Patent Document 1, hydrogen is supplied from the hydrogen supply source 1 to the hydrogen supply port of the fuel cell 3 through the fuel supply path 2 as shown in FIG. Hydrogen that has not been consumed in the fuel cell 3 is discharged as a hydrogen off-gas to the hydrogen circulation path 4, and an ejector 5 is interposed at the junction of the hydrogen circulation path 4 and the fuel supply path 2.

  The ejector 5 includes a main flow port 5a through which new hydrogen is introduced from the hydrogen supply source 1, a suction unit 5b that is connected to the hydrogen circulation path 4 and that sucks off hydrogen gas discharged from the fuel cell 3, and an air supply path. 2 and a discharge part 5c that discharges a new mixed gas of hydrogen and hydrogen off-gas to the fuel cell 3 side. In the ejector 5, a film 8 made of a fluororesin is formed on the inner wall surfaces of the suction part 5 b, the mixing part 6, and the diffuser part 7.

  As a result, a film 8 is formed on the inner region of the ejector 5 in which the high-humidity hydrogen off-gas flows, that is, on the inner wall surfaces of the suction part 5 b, the mixing part 6 and the diffuser part 7. For this reason, it is said that adhesion of water droplets to the inner wall surface is suppressed.

JP 2006-294347 A

  However, in Patent Document 1 described above, water droplets (water) discharged from the ejector 5 are distributed in the fuel cell 3. For this reason, there is a possibility that water droplets may flow through the fuel gas flow passage extending in the direction of the power generation surface from the fuel gas supply communication hole and block them. As a result, there is a problem that the power generation performance of the fuel cell 3 is lowered and efficient power generation is not performed.

  An object of the present invention is to solve this type of problem, and to provide a fuel cell system capable of preventing condensate from entering a power generation cell with a simple configuration as much as possible. To do.

  The present invention includes a power generation cell in which an electrolyte / electrode structure in which a pair of electrodes are arranged on both sides of an electrolyte and a separator are stacked, and the plurality of power generation cells are stacked in the direction of gravity with the electrode surface being a horizontal plane. And a reaction gas flow channel for flowing the reaction gas along the electrode surface direction, and a reaction gas supply channel for communicating with the reaction gas flow channel and for flowing the reaction gas downward in the direction of gravity along the stacking direction of the separator. A fuel cell stack in which a hole and a reaction gas discharge communication hole are formed, and a circulation pipe that connects an outlet of the reaction gas discharge communication hole and an inlet of the reaction gas supply communication hole outside the fuel cell stack And a reaction gas supply device that circulates and supplies the reaction gas to the reaction gas flow path.

The reaction gas supply device includes an ejector disposed in a vertical pipe portion that constitutes a circulation pipe and extends in a direction of gravity, and a reaction gas flow path in the vertical pipe portion that is positioned below the suction port of the ejector. In order to remove moisture in the reaction gas that is arranged and flows upward in the direction of gravity, the reaction gas circulates around the entire inner peripheral wall surface forming the reactive gas flow passage and continuously from the entire inner peripheral wall surface. A baffle member protruding inward of the flow passage is provided.

  Further, the baffle member preferably has a reduced diameter passage portion communicating with the suction port of the ejector in a state where the opening diameter in the vertical piping portion is reduced.

Furthermore, the fuel cell stack, the bottom side of the baffle member, it is preferable that the gas-liquid separator is arranged.

  The reactive gas is preferably a fuel gas.

  According to the present invention, the vertical pipe portion that constitutes the circulation pipe and extends in the gravity direction has a direction from the outlet of the reaction gas discharge communication hole toward the inlet of the reaction gas supply communication hole, that is, from the lower side to the upper side in the gravity direction. The reaction gas is circulating. For this reason, the reaction gas discharged from the outlet of the reaction gas discharge communication hole is introduced into the introduction port of the ejector after moisture is removed by the baffle member. Therefore, the reaction gas from which moisture has been removed is mixed with new reaction gas from the outlet of the ejector and supplied to the inlet of the reaction gas supply passage.

  Therefore, the reaction gas flowing upward from below along the vertical piping portion that constitutes the circulation piping and extends in the direction of gravity removes moisture (condensed water) by its own weight, and the moisture is further removed by the baffle member. Has been removed. Accordingly, it is possible to prevent the condensed water from entering the power generation cell with a simple configuration as much as possible, and the power generation function can be easily improved.

1 is an explanatory diagram of a schematic configuration of a fuel cell system according to a first embodiment of the present invention. It is a disassembled perspective explanatory drawing of the power generation cell which comprises the said fuel cell system. It is principal part sectional drawing of the said fuel cell system. It is principal part cross-sectional explanatory drawing of the fuel cell system which concerns on the 2nd Embodiment of this invention. It is principal part sectional explanatory drawing of the fuel cell system which concerns on the 3rd Embodiment of this invention. It is principal part sectional explanatory drawing of the fuel cell system which concerns on the 4th Embodiment of this invention. 2 is an explanatory diagram of a fuel cell system disclosed in Patent Document 1. FIG.

  As shown in FIG. 1, the fuel cell system 10 according to the first embodiment of the present invention is configured for in-vehicle use, for example, and includes a fuel cell stack 12.

  In the fuel cell stack 12, a plurality of power generation cells (unit cells) 14 are stacked in the gravity direction (arrow A direction) with the electrode surface as a horizontal plane. At one end (upper end) of the power generation cell 14 in the stacking direction (arrow A direction), a terminal plate 16a, an insulating plate 18a, and an end plate 20a are disposed upward. At the other end (lower end) of the power generation cell 14 in the stacking direction, a terminal plate 16b, an insulating plate 18b, and an end plate 20b are disposed downward.

  Both ends of a plurality of connecting bars 21 are fixed to the end plates 20a and 20b, and a tightening load is applied between the end plates 20a and 20b in the stacking direction. A tightening load may be applied between the end plates 20a and 20b in the stacking direction via a tie rod (not shown), or a tightening load may be applied in the stacking direction via a box-shaped casing.

  As shown in FIG. 2, each power generation cell 14 includes an electrolyte membrane / electrode structure (MEA) 22, and a first metal separator 24 and a second metal separator 26 that sandwich the electrolyte membrane / electrode structure 22. .

  The first metal separator 24 and the second metal separator 26 are made of, for example, a steel plate, a stainless steel plate, an aluminum plate, a plated steel plate, or a vertically long metal plate having a surface treated for anticorrosion on the metal surface. The first and second metal separators 24 and 26 have a rectangular planar shape, and are formed into a concavo-convex shape by pressing a metal thin plate into a corrugated plate shape. Instead of the first metal separator 24 and the second metal separator 26, for example, a carbon separator (not shown) may be used.

  One end edge of the power generation cell 14 in the direction of arrow B (horizontal direction) communicates with each other in the direction of arrow A, and an oxidant gas supply communication hole (reactive gas) for supplying an oxidant gas, for example, an oxygen-containing gas. A supply communication hole) 28a, a cooling medium supply communication hole 30a for supplying a cooling medium, and a fuel gas discharge communication hole (reactive gas discharge communication hole) 32b for discharging a fuel gas, for example, a hydrogen-containing gas. .

  The other end edge of the power generation cell 14 in the direction of arrow B communicates with each other in the direction of arrow A, discharges a fuel gas supply communication hole (reaction gas supply communication hole) 32a for supplying fuel gas, and discharges the cooling medium. A cooling medium discharge communication hole 30b for the purpose and an oxidant gas discharge communication hole (reactive gas discharge communication hole) 28b for discharging the oxidant gas are provided.

  The oxidant gas supply communication hole 28a, the oxidant gas discharge communication hole 28b, the cooling medium supply communication hole 30a, the cooling medium discharge communication hole 30b, the fuel gas supply communication hole 32a, and the fuel gas discharge communication hole 32b are respectively oxidant gas, The flow direction of the cooling medium and the fuel gas is set below the gravity direction.

  On the surface 24a of the first metal separator 24 on the electrolyte membrane / electrode structure 22 side, for example, an oxidant gas flow path 36 extending in the arrow B direction (electrode surface direction) is provided. The oxidant gas flow path 36 communicates with the oxidant gas supply communication hole 28a and the oxidant gas discharge communication hole 28b. A cooling medium flow path 38 is formed on the surface 24 b opposite to the surface 24 a of the first metal separator 24. The cooling medium flow path 38 communicates with the cooling medium supply communication hole 30a and the cooling medium discharge communication hole 30b.

  The surface 26a of the second metal separator 26 on the electrolyte membrane / electrode structure 22 side communicates with the fuel gas supply communication hole 32a and the fuel gas discharge communication hole 32b and extends in the direction of arrow B (electrode surface direction). A fuel gas flow path 40 is formed. The cooling medium flow communicating with the cooling medium supply communication hole 30a and the cooling medium discharge communication hole 30b is overlapped with the surface 24b of the first metal separator 24 on the surface 26b opposite to the surface 26a of the second metal separator 26. A path 38 is formed.

  In the first metal separator 24, the first seal member 42 is integrally injection-molded on the metal thin plate, and in the second metal separator 26, the second seal member 44 is integrally injection-molded on the metal thin plate.

  The first and second sealing members 42 and 44 are, for example, EPDM, NBR, fluorine rubber, silicone rubber, fluorosilicone rubber, butyl rubber, natural rubber, styrene rubber, chloroprene, acrylic rubber, or other sealing materials, cushion materials, Alternatively, a packing material is used.

  The electrolyte membrane / electrode structure 22 includes, for example, a solid polymer electrolyte membrane (electrolyte) 52 in which a perfluorosulfonic acid thin film is impregnated with water, a cathode side electrode 54 and an anode sandwiching the solid polymer electrolyte membrane 52 Side electrode 56.

  The cathode side electrode 54 and the anode side electrode 56 are formed by uniformly applying a gas diffusion layer made of carbon paper or the like and porous carbon particles carrying a platinum alloy on the surface thereof to the surface of the gas diffusion layer. An electrode catalyst layer. The electrode catalyst layers are formed on both surfaces of the solid polymer electrolyte membrane 52.

  As shown in FIG. 1, the fuel cell system 10 includes an air supply device 60 for supplying air, which is an oxidant gas, to the fuel cell stack 12, a cooling medium supply device 62 for supplying a cooling medium, And a hydrogen supply device (reactive gas supply device) 64 for supplying hydrogen gas as fuel gas.

  The air supply device 60 includes an air pump 66, and an air supply path 68 to which the air pump 66 is connected communicates with the oxidant gas supply communication hole 28 a of the fuel cell stack 12 via a humidifier 70.

  The air supply device 60 includes an air discharge path 72 that communicates with the oxidant gas discharge communication hole 28 b of the fuel cell stack 12, and the air discharge path 72 extends outside the vehicle via a humidifier 70. The humidifier 70 humidifies the new air by exchanging water between the used humidified air discharged to the air discharge path 72 and the new air introduced to the air supply path 68. .

  The cooling medium supply device 62 includes a radiator 74. A cooling medium circulation path 76 is connected to the radiator 74, and both ends of the cooling medium circulation path 76 are connected to the cooling medium supply communication hole 30 a and the cooling medium discharge communication hole 30 b of the fuel cell stack 12. A refrigerant pump 78 is interposed in the cooling medium circulation path 76.

  The hydrogen supply device 64 includes a hydrogen tank 80 that stores high-pressure hydrogen, and the hydrogen tank 80 is disposed in the hydrogen supply path 82. The hydrogen supply path 82 communicates with the fuel gas supply communication hole 32a of the fuel cell stack 12, and a pressure reducing valve 84 and an ejector 86 are provided.

  The hydrogen supply device 64 includes a hydrogen circulation path (circulation piping) 88 that communicates with the fuel gas discharge communication hole 32 b of the fuel cell stack 12, and the hydrogen circulation path 88 is interposed with a gas-liquid separator 90 and an ejector 86. Communicate with. The ejector 86 is disposed in a vertical piping section 88a that forms a hydrogen circulation path 88 and extends in the direction of gravity.

  As shown in FIG. 3, the ejector 86 is arranged such that the inlet 92a faces downward and the outlet 92b faces upward. The ejector 86 has a nozzle portion 94 and a diffuser portion 96 upward from the introduction port 92 a, and the suction port 100 communicates with the nozzle portion 94 via a suction chamber 98.

  The suction port 100 communicates with the vertical piping portion 88a of the hydrogen circulation path 88, and the vertical piping portion 88a has a hydrogen gas flow passage (reaction) in order to remove moisture in the hydrogen gas flowing upward in the gravity direction. A baffle plate (baffle member) 104 projecting into the (gas flow passage) 102 is disposed. The baffle plate 104 has a substantially conical shape whose diameter is reduced downward, and is disposed in the vicinity of the suction port 100.

  The operation of the fuel cell system 10 configured as described above will be described below.

  First, as shown in FIG. 1, in the air supply device 60, the compressed air led to the air supply path 68 is humidified by the humidifier 70 under the driving action of the air pump 66, and then oxidized in the fuel cell stack 12. It is supplied to the agent gas supply communication hole 28a.

  In the hydrogen supply device 64, the high-pressure hydrogen stored in the hydrogen tank 80 is depressurized via the pressure reducing valve 84 and sent to the hydrogen supply path 82. The fuel gas (hydrogen gas) is ejected from the nozzle portion 94 of the ejector 86, and used fuel gas, which will be described later, is sucked and supplied to the fuel gas supply communication hole 32a of the fuel cell stack 12.

  On the other hand, in the cooling medium supply device 62, the cooling medium is supplied from the cooling medium circulation path 76 to the cooling medium supply communication hole 30 a of the fuel cell stack 12 under the action of the refrigerant pump 78.

  Therefore, as shown in FIG. 2, the oxidant gas is introduced into the oxidant gas flow path 36 of the first metal separator 24 from the oxidant gas supply communication hole 28 a. The oxidant gas is supplied to the cathode side electrode 54 constituting the electrolyte membrane / electrode structure 22 while moving in the arrow B direction along the oxidant gas flow path 36.

  On the other hand, the fuel gas is introduced into the fuel gas flow path 40 of the second metal separator 26 from the fuel gas supply communication hole 32a. The fuel gas is supplied to the anode-side electrode 56 constituting the electrolyte membrane / electrode structure 22 while moving in the arrow B direction along the fuel gas flow path 40.

  Therefore, in the electrolyte membrane / electrode structure 22, the oxidant gas supplied to the cathode side electrode 54 and the fuel gas supplied to the anode side electrode 56 are consumed by an electrochemical reaction in the electrode catalyst layer, thereby generating power. Is done.

  Next, the oxidant gas consumed by being supplied to the cathode side electrode 54 moves downward in the gravity direction along the oxidant gas discharge communication hole 28b, and is discharged to the air discharge path 72 (see FIG. 1). The oxidant gas is humidified with a new oxidant gas by the humidifier 70 and then discharged outside the vehicle.

  On the other hand, the fuel gas consumed by being supplied to the anode side electrode 56 moves downward in the direction of gravity along the fuel gas discharge communication hole 32 b and is discharged to the hydrogen circulation path 88. As shown in FIG. 3, the fuel gas is sucked into the suction chamber 98 from the suction port 100 under the suction action of the ejector 86. Therefore, the fuel gas is mixed with new fuel gas, introduced into the hydrogen supply path 82, and supplied to the fuel cell stack 12 as the fuel gas (see FIG. 1).

  Further, the cooling medium (pure water, ethylene glycol, oil, etc.) supplied to the cooling medium supply communication hole 30a is a cooling medium flow path 38 between the first and second metal separators 24 and 26 as shown in FIG. Circulated in the direction of arrow B. The cooling medium is discharged to the cooling medium discharge communication hole 30b after the electrolyte membrane / electrode structure 22 is cooled. As shown in FIG. 1, the cooling medium is returned to the cooling medium circulation path 76, cooled by the radiator 74, and then circulated and supplied to the fuel cell stack 12.

In this case, in the first embodiment, the vertical pipe portion 88a extending in the direction of gravity and constitute the hydrogen circulation path 88, together with the ejector 86 is arranged, located under side of the suction port 100 of the ejector 86 The baffle plate 104 is provided in the vertical piping portion 88a (see FIG. 3).

  Accordingly, the fuel gas discharged to the fuel gas discharge communication hole 32b of the fuel cell stack 12 flows from the lower side to the upper side in the direction of gravity along the vertical pipe portion 88a and is blown to the baffle plate 104. For this reason, the condensed water (condensed water) that moves vertically along with the fuel gas is blocked by the baffle plate 104 and cannot move to the suction port 100 side. As a result, the dew condensation water flows downward in the vertical pipe portion 88 a by its own weight and is captured by the gas-liquid separator 90.

  The fuel gas that has passed through the baffle plate 104 is sucked from the suction port 100 after the condensed water is removed, mixed with new fuel gas in the diffuser unit 96, and then the fuel gas in the fuel cell stack 12 through the hydrogen supply path 82. It is supplied to the supply communication hole 32a.

  Accordingly, it is possible to prevent the condensed water from entering the fuel cell stack 12 with a simple configuration as much as possible, prevent the fuel gas flow paths 40 from being blocked, and generate power. It is possible to obtain an effect that the improvement of the above can be easily achieved.

  FIG. 4 is an explanatory cross-sectional view of a main part of a fuel cell system 120 according to the second embodiment of the present invention.

  Note that the same components as those of the fuel cell system 10 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. The detailed description of the third and subsequent embodiments described below is also omitted.

In the fuel cell system 120, the vertical pipe section 88a located under side of the suction port 100 of the ejector 86, baffle plate (baffle member) 122 is provided. The baffle plate 122 is configured in a ring shape, and has a function of removing moisture in the fuel gas flowing in the upward direction of gravity.

  Therefore, in the second embodiment, with the simple configuration, it is possible to prevent the condensed water from entering the power generation cell 14 as much as possible, and the power generation performance is improved. The same effect as that of the first embodiment can be obtained.

  FIG. 5 is an explanatory cross-sectional view of a main part of a fuel cell system 130 according to the third embodiment of the present invention.

In the fuel cell system 130, located under side of the suction port 100 of the ejector 86, baffle member 132 is provided. The baffle member 132 has a reduced diameter passage portion 134 that communicates with the suction port 100 in a state where the opening diameter D1 of the vertical pipe portion 88a is reduced to the opening diameter D2 (D1> D2).

  FIG. 6 is an explanatory cross-sectional view of a main part of a fuel cell system 140 according to the fourth embodiment of the present invention.

In the fuel cell system 140, located under side of the suction port 100 of the ejector 86, baffle member 142 is provided. The baffle member 142 has an inclined surface (tapered surface) 144 at the end (lower end) in the vertically downward direction, and the opening diameter D1 of the vertical pipe portion 88a is reduced to the opening diameter D3 (D1> D3). In the state, it has a reduced diameter passage portion 146 extending to the suction port 100.

  In the third and fourth embodiments, the baffle members 132 and 142 are respectively provided with the reduced diameter passage portions 134 and 146 extending to the suction port 100. Therefore, moisture is removed from the fuel gas via the baffle members 132 and 142, and the fuel gas introduced into the reduced diameter passage portions 134 and 146 and having a high flow rate is sent to the suction port 100 of the ejector 86. it can.

  Thereby, the suction effect from the suction port 100 by the ejector 86 is increased, and there is an advantage that the flow rate of the fuel gas sucked from the vertical pipe portion 88a is efficiently increased.

DESCRIPTION OF SYMBOLS 10, 120, 130, 140 ... Fuel cell system 12 ... Fuel cell stack 14 ... Power generation cell 20a, 20b ... End plate 21 ... Connection bar 22 ... Electrolyte membrane and electrode structure 24, 26 ... Metal separator 28a ... Oxidant gas supply Communication hole 28b ... Oxidant gas discharge communication hole 30a ... Cooling medium supply communication hole 30b ... Cooling medium discharge communication hole 32a ... Fuel gas supply communication hole 32b ... Fuel gas discharge communication hole 36 ... Oxidant gas flow path 38 ... Cooling medium flow Path 40 ... Fuel gas flow path 52 ... Solid polymer electrolyte membrane 54 ... Cathode side electrode 56 ... Anode side electrode 60 ... Air supply device 62 ... Cooling medium supply device 64 ... Hydrogen supply device 86 ... Ejector 88 ... Hydrogen circulation path 88a ... Vertical piping part 90 ... Gas-liquid separator 92a ... Inlet port 92b ... Outlet port 94 ... Nozzle part 96 ... Diffuser part 98 ... Suction chamber 1 0 ... suction port 102 ... hydrogen gas passages 104,122 ... baffles 132, 142 ... baffle members 134,146 ... reduced-diameter passage portion 144 ... inclined surface

Claims (4)

A power generation cell in which an electrolyte / electrode structure having a pair of electrodes disposed on both sides of an electrolyte and a separator are stacked, and the plurality of power generation cells are stacked in the direction of gravity with the electrode surface as a horizontal plane, and a reactive gas A reaction gas flow path that circulates along the electrode surface direction, a reaction gas supply communication hole that communicates with the reaction gas flow path, and that circulates the reaction gas downward in the direction of gravity along the stacking direction of the separator. A fuel cell stack in which a discharge communication hole is formed;
A reaction gas supply comprising a circulation pipe for connecting the outlet of the reaction gas discharge communication hole and the inlet of the reaction gas supply communication hole outside the fuel cell stack, and supplying the reaction gas to the reaction gas flow path Equipment,
A fuel cell system comprising:
The reactive gas supply device includes an ejector disposed in a vertical piping portion that constitutes the circulation piping and extends in the direction of gravity.
The reaction gas flow path is formed in order to remove moisture in the reaction gas that is located below the intake port of the ejector and is disposed in the reaction gas flow path in the vertical pipe portion and flows upward in the gravity direction. A baffle member that circulates over the entire circumference of the inner circumferential wall surface and continuously protrudes from the entire circumference of the inner circumferential wall surface ;
A fuel cell system comprising: In claim 1 Symbol placement of the fuel cell system, wherein the baffle member is in a state of being contracted the aperture diameter in the vertical pipe portion, and characterized in that it has a reduced diameter passage portion communicating with the suction port of the ejector Fuel cell system. 3. The fuel cell system according to claim 1, wherein a gas-liquid separator is disposed below the baffle member. A fuel cell system according to any one of claims 1 to 3 fuel cell system, wherein the reaction gas is a fuel gas.

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