JP5584710B2 - Fuel cell - Google Patents

Description

  In the present invention, an electrolyte membrane / electrode structure provided with a pair of electrodes on both sides of an electrolyte membrane and a separator are laminated, and a reaction gas flow path for supplying a reaction gas is formed along the electrode surface. The present invention relates to a fuel cell provided with an inlet buffer section communicating with an inlet side of a gas flow path and an outlet buffer section communicating with an outlet side of the reaction gas flow path.

  For example, in a polymer electrolyte fuel cell, an electrolyte membrane / electrode structure (MEA) in which an anode side electrode and a cathode side electrode are disposed on both sides of an electrolyte membrane made of a polymer ion exchange membrane is sandwiched by separators. A unit cell is provided. This type of fuel cell is normally used as a fuel cell stack by stacking a predetermined number of unit cells.

  In the above fuel cell, a fuel gas channel (reaction gas channel) for flowing fuel gas to the anode side electrode and an oxidant gas channel for flowing oxidant gas to the cathode side electrode in the plane of the separator (Reactive gas flow path) is provided. Furthermore, a cooling medium flow path for flowing a cooling medium is provided along the surface direction of the separator for each power generation cell or for each of the plurality of power generation cells.

  This type of fuel cell has a so-called internal structure in which a reaction gas inlet communication hole, a reaction gas outlet communication hole, a cooling medium inlet communication hole, and a cooling medium outlet communication hole penetrating in the stacking direction of the separator are provided in the fuel cell. A manifold may be configured.

  At this time, generally, an inlet buffer portion is provided between the reactive gas inlet communication hole and the reactive gas flow path in order to uniformly distribute and supply the reactive gas to the reactive gas flow path. . On the other hand, an outlet buffer section is provided between the reaction gas flow path and the reaction gas outlet communication hole in order to allow the reaction gas to uniformly join the reaction gas outlet communication hole.

  For example, in Patent Document 1, as shown in FIG. 10, the gas flow path 2 of the separator 1 has a flow path width formed wider than the inlet and outlet passage widths to the inlet manifold 3a and the outlet manifold 3b. A main flow path portion 2a having a rib 4a that divides a flow path into a plurality of parts, and a rib 4b that is arranged between an inlet or outlet to the inlet manifold 3a or the outlet manifold 3b and the main flow path section 2a and divides the flow path into a plurality of times. 4c and a flow distribution section 2b and a merge section 2c provided with gaps 5a and 5b for redistribution or recombination between the ends of the ribs 4b and 4c and the rib 4a of the main flow path section 2a. doing.

  And in the longitudinal direction position of the separator 1 where the gaps 5a and 5b for redistribution or recombination exist, ribs 4b and 4c that divide the flow path from the main flow path part 2a or the distribution part 2b or the merge part 2c are provided. There are at least one extended rib.

JP 2006-172924 A

  In the above-mentioned patent document 1, since the flow distribution section 2b and the merge section 2c are configured to be equivalent, the flow distribution section 2b and the merge section 2c have the same flow path resistance. Here, when the gas flow path 2 is a fuel gas flow path for supplying pure hydrogen to the anode side electrode in particular, hydrogen is consumed in the fuel gas flow path by power generation, and the fuel gas flow path is connected to the inlet side of the fuel gas flow path. The flow rate is decreasing at the outlet side.

  At that time, in Patent Document 1 described above, the pressure loss in the flow distribution section 2b is larger than the pressure loss in the merge section 2c, and hydrogen preferentially flows into the flow path adjacent to the inlet manifold 3a. On the other hand, hydrogen shortage occurs in the flow path away from the inlet manifold 3a. Thereby, there is a problem that the power generation performance is deteriorated and the electrode is deteriorated.

  The present invention solves this kind of problem, and the reaction gas can be uniformly distributed to the reaction gas flow path communicating with the inlet buffer portion and the outlet buffer portion, and the power generation performance is excellent with a simple configuration. It is an object of the present invention to provide a fuel cell that can be maintained in the above manner.

  In the present invention, an electrolyte membrane / electrode structure provided with a pair of electrodes on both sides of an electrolyte membrane and a separator are laminated, and a reaction gas flow path for supplying a reaction gas is formed along the electrode surface. The present invention relates to a fuel cell in which an inlet buffer portion communicating with an inlet side of a gas flow channel and an outlet buffer portion communicating with an outlet side of the reaction gas flow channel are provided.

In this fuel cell, the reaction gas channel has a plurality of linear channel grooves formed between the plurality of linear projections, and the inlet buffer unit and the outlet buffer unit have a plurality of groove parts via the projections. And a part of the protrusions of the inlet buffer part and the outlet buffer part is provided continuously with a part of the linear protrusion part of the reaction gas flow path, and a groove width of the inlet buffer part Is set to be wider than the groove width of the outlet buffer portion.

  According to the present invention, the pressure loss of the inlet buffer portion is set smaller than the pressure loss of the outlet buffer portion. For this reason, when the reaction gas is consumed in the reaction gas channel by power generation, the pressure loss of the inlet buffer unit and the pressure loss of the outlet buffer unit become equal, and the reaction gas is evenly distributed to the reaction gas channel. be able to. This makes it possible to maintain a desired power generation performance with a simple configuration.

It is an exploded perspective view showing a fuel cell that are related to the present invention. It is front explanatory drawing of the 1st separator which comprises the said fuel cell. It is the III-III sectional view taken on the line of the 2nd separator which comprises the said fuel cell in FIG. FIG. 7 is an explanatory diagram showing changes in the flow rate of fuel gas from the inlet side to the outlet side of the flow channel in the conventional example and the fuel cell . It is an exploded perspective view showing a fuel cell that are related to the present invention. FIG. 6 is a cross-sectional view of the second separator constituting the fuel cell, taken along line VI-VI in FIG. 5. It is an exploded perspective view showing a fuel cell that are related to the present invention. It is the VIII-VIII sectional view taken on the line of the 2nd separator which comprises the said fuel cell in FIG. It is a front view showing a second separator of a fuel cell according to the implementation embodiments of the present invention. 6 is a front explanatory view of a fuel cell separator of Patent Document 1. FIG.

Figure 1 is an exploded perspective view showing a fuel cell 10 that relate to the present invention.

  In the fuel cell 10, the electrolyte membrane / electrode structure 14 is sandwiched between a first separator (cathode side separator) 16 and a second separator (anode side separator) 18. The first and second separators 16 and 18 are made of, for example, a carbon separator, but are made of a steel plate, a stainless steel plate, an aluminum plate, a plated steel plate, or a metal separator whose surface has been subjected to anticorrosion treatment. It may be configured.

  An oxidant gas (reactive gas), for example, an oxygen-containing gas is supplied to one edge of the fuel cell 10 in the direction of arrow B (horizontal direction in FIG. 1) in communication with the direction of arrow A, which is the stacking direction. An oxidant gas inlet communication hole 20a for supplying a cooling medium, a cooling medium inlet communication hole 22a for supplying a cooling medium, and a fuel gas outlet communication hole 24b for discharging a fuel gas (reactive gas), for example, a hydrogen-containing gas. Are arranged in the direction of arrow C (vertical direction).

  The other end edge of the fuel cell 10 in the direction of arrow B communicates with each other in the direction of arrow A, the fuel gas inlet communication hole 24a for supplying fuel gas, and the cooling medium outlet communication hole for discharging the cooling medium. 22b and an oxidant gas outlet communication hole 20b for discharging the oxidant gas are arranged in the direction of arrow C.

  The electrolyte membrane / electrode structure 14 includes, for example, a solid polymer electrolyte membrane 26 in which a perfluorosulfonic acid thin film is impregnated with water, and a cathode side electrode 28 and an anode side electrode 30 that sandwich the solid polymer electrolyte membrane 26. With. The anode side electrode 30 has a smaller surface area than the cathode side electrode 28.

  The cathode side electrode 28 and the anode side electrode 30 are uniformly coated with a gas diffusion layer (not shown) made of carbon paper or the like and porous carbon particles carrying a platinum alloy on the surface thereof. And an electrode catalyst layer (not shown) formed. The electrode catalyst layers are formed on both surfaces of the solid polymer electrolyte membrane 26.

  An oxidant gas flow path (reaction gas flow path) 32 is provided on the surface 16 a of the first separator 16 facing the electrolyte membrane / electrode structure 14. As shown in FIG. 2, the oxidant gas channel 32 has a plurality of linear channel grooves 32 b formed between a plurality of linear protrusions 32 a extending in the arrow B direction.

  An inlet buffer section 34 communicates with the inlet side of the oxidant gas flow path 32, and an outlet buffer section 36 communicates with the outlet side of the oxidant gas flow path 32. The inlet buffer part 34 has a plurality of embosses 34a, while the outlet buffer part 36 has a plurality of embosses 36a.

  As shown in FIG. 1, a cooling medium flow path 38 is provided on the surface 16 b opposite to the surface 16 a of the first separator 16. The cooling medium channel 38 has a plurality of linear channel grooves 38b formed between a plurality of linear projections 38a extending in the direction of arrow B. An inlet buffer unit 40 and an outlet buffer unit 42 communicate with the cooling medium flow path 38. The inlet buffer unit 40 has a plurality of embosses 40a, while the outlet buffer unit 42 has a plurality of embosses 42a.

  A fuel gas channel (reactive gas channel) 44 is provided on the surface 18 a of the second separator 18 facing the electrolyte membrane / electrode structure 14. The fuel gas channel 44 has a plurality of linear channel grooves 44b formed between a plurality of linear protrusions 44a extending in the arrow B direction.

  An inlet buffer unit 46 communicates with the inlet side of the fuel gas channel 44, and an outlet buffer unit 48 communicates with the outlet side of the fuel gas channel 44. The inlet buffer unit 46 has a plurality of embosses 46a, while the outlet buffer unit 48 has a plurality of embosses 48a.

  In the second separator 18, a plurality of supply holes 49a are formed in the vicinity of the fuel gas inlet communication hole 24a, and a plurality of discharge holes 49b are formed in the vicinity of the fuel gas outlet communication hole 24b. The supply hole portion 49a communicates with the fuel gas inlet communication hole 24a on the surface 18b side, and communicates with the inlet buffer portion 46 on the surface 18a side. Similarly, the discharge hole portion 49b communicates with the fuel gas outlet communication hole 24b on the surface 18b side, and communicates with the outlet buffer portion 48 on the surface 18a side.

On the fuel gas flow path 44 side, the pressure loss of the inlet buffer unit 46 is set smaller than the pressure loss of the outlet buffer unit 48 . As shown in FIG. 3, the depth H1 of the inlet buffer 46 is set to be greater than the depth H2 of the outlet buffer 48 (H1> H2).

In order to equalize the pressure loss of the inlet buffer unit 46 and the pressure loss of the outlet buffer unit 48 when the fuel gas inlet flow rate Q1 and the fuel gas outlet flow rate Q2, the respective depths H1 and H2 are: It is set from the relationship of ^{H1 / H2 = 3 √Q1 / Q2} .

  On the oxidant gas channel 32 side, the pressure loss of the inlet buffer unit 34 is set to be smaller than the pressure loss of the outlet buffer unit 36, as necessary, as with the fuel gas channel 44 side.

  As shown in FIGS. 1 and 2, seal members 50 and 52 such as gaskets are provided on the outer peripheral edge portions of the surfaces 16 a and 16 b of the first separator 16. As shown in FIG. 1, a seal member 54 such as a gasket is provided on the outer peripheral edge portion of the surface 18 a of the second separator 18.

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

  First, as shown in FIG. 1, an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas inlet communication hole 20a, and a fuel gas such as a hydrogen-containing gas is supplied to the fuel gas inlet communication hole 24a. Further, a cooling medium such as pure water, ethylene glycol, or oil is supplied to the cooling medium inlet communication hole 22a.

  Therefore, the oxidant gas is introduced into the inlet buffer portion 34 of the first separator 16 from the oxidant gas inlet communication hole 20a as shown in FIG. The oxidant gas is distributed and supplied from the inlet buffer 34 to the plurality of flow channel grooves 32b that constitute the oxidant gas flow channel 32. The oxidant gas moves in the direction of arrow B along each flow channel 32b and is supplied to the cathode side electrode 28 of the electrolyte membrane / electrode structure 14.

  On the other hand, as shown in FIG. 1, the fuel gas moves from the fuel gas inlet communication hole 24 a to the surface 18 a side through the supply hole portion 49 a on the surface 18 b side of the second separator 18 and is introduced into the inlet buffer portion 46. The The fuel gas is distributed and supplied from the inlet buffer unit 46 to the plurality of flow channel grooves 44 b constituting the fuel gas flow channel 44. The fuel gas moves in the direction of arrow B along each flow channel 44b and is supplied to the anode electrode 30 of the electrolyte membrane / electrode structure 14.

  Therefore, in each electrolyte membrane / electrode structure 14, the oxidant gas supplied to the cathode side electrode 28 and the fuel gas supplied to the anode side electrode 30 are consumed by an electrochemical reaction in the electrode catalyst layer, Power generation is performed.

  As shown in FIG. 2, the oxidant gas flowing along each flow channel 32b joins at the outlet buffer 36 and is then discharged to the oxidant gas outlet communication hole 20b. Further, as shown in FIG. 1, the fuel gas flowing along each flow channel groove 44b joins at the outlet buffer portion 48, and then is discharged to the fuel gas outlet communication hole 24b through the discharge hole portion 49b.

  The cooling medium is introduced into the inlet buffer 40 formed between the first separator 16 and the second separator 18 from the cooling medium inlet communication hole 22a. The cooling medium is supplied from the inlet buffer unit 40 to a plurality of flow path grooves 38 b that constitute the cooling medium flow path 38. This cooling medium moves in the direction of arrow B along each flow path groove 38b, cools the power generation surface of the electrolyte membrane / electrode structure 14, and then merges at the outlet buffer section 42 to the cooling medium outlet communication hole 22b. Discharged.

  In this case, particularly in the fuel gas passage 44, the fuel gas supplied to the fuel gas passage 44 is consumed by the power generation reaction. For this reason, the fuel gas has an outlet flow rate Q2 that decreases with respect to the inlet flow rate Q1 (Q1> Q2), and the flow path resistance of the outlet buffer 48 decreases.

Therefore, in the fuel cell 10 , the pressure loss of the inlet buffer unit 46 is set to be smaller than the pressure loss of the outlet buffer unit 48. Specifically, as shown in FIG. 3, the depth H1 of the inlet buffer section 46 is set to be greater than the depth H2 of the outlet buffer section 48 (H1> H2).

  Thereby, when fuel gas is consumed in the fuel gas flow path 44 by power generation, the pressure loss of the inlet buffer unit 46 and the pressure loss of the outlet buffer unit 48 become equal. Therefore, the fuel gas can be evenly distributed to the fuel gas flow path 44, and the desired power generation performance can be satisfactorily maintained with a simple configuration.

FIG. 4 shows the change in the fuel gas flow rate (hydrogen flow rate) from the inlet side to the outlet side of the channel groove 44b in the fuel cell 10 and the conventional example in which the pressure loss of the inlet buffer portion and the outlet buffer portion is the same. It is shown. Thereby, in the conventional example, the fuel gas flow rate decreases as it goes to the outlet side of the flow channel groove 44b, whereas in the fuel cell 10 , the fuel gas flow rate is made uniform over the entire flow channel groove 44b.

  In the oxidant gas flow channel 32 as well, the pressure loss of the inlet buffer unit 34 is set to be smaller than the pressure loss of the outlet buffer unit 36 as necessary. For this reason, the effect similar to said fuel gas flow path 44 is acquired.

Figure 5 is an exploded perspective view showing a fuel cell 60 that relate to the present invention. Note that the fuel cell 10 the same components as are designated by the same reference numerals, and detailed description thereof will be omitted.

  In the fuel cell 60, the electrolyte membrane / electrode structure 14 is sandwiched between a first separator 16 and a second separator (anode separator) 62. The second separator 62 includes an inlet buffer portion 66 that communicates with the inlet side of the fuel gas passage 44 and an outlet buffer portion 48 that communicates with the outlet side of the fuel gas passage 44.

  As shown in FIGS. 5 and 6, the inlet buffer 66 is provided with a deep groove region 66a having a large depth H1 at least in part. The deep groove region 66a is configured to be narrower, that is, substantially triangular, as the distance from the fuel gas inlet communication hole 24a increases. The other part of the inlet buffer 66 is set to a depth H2 (H1> H2) equivalent to that of the outlet buffer 48.

In the fuel cell 60 configured as described above, the deep buffer region 66 a is provided in at least a part of the inlet buffer 66, so that the pressure loss of the inlet buffer 66 is set smaller than the pressure loss of the outlet buffer 48. . Therefore, when fuel gas is consumed in the fuel gas flow path 44 by power generation, the pressure loss of the inlet buffer portion 66 and the pressure loss of the outlet buffer portion 48 become equal, and the same effect as the fuel cell 10 described above can be obtained. .

Figure 7 is an exploded perspective view showing a fuel cell 70 that relate to the present invention.

  In the fuel cell 70, the electrolyte membrane / electrode structure 14 is sandwiched between a first separator 16 and a second separator (anode separator) 72. The second separator 72 includes an inlet buffer portion 46 that communicates with the inlet side of the fuel gas passage 44 and an outlet buffer portion 74 that communicates with the outlet side of the fuel gas passage 44.

  As shown in FIGS. 7 and 8, the outlet buffer unit 74 is provided with a shallow groove region 74a having a small depth H2 at least partially. The shallow groove region 74a is configured to be narrower, that is, substantially triangular, as the distance from the fuel gas outlet communication hole 24b increases. The other part of the outlet buffer part 74 is set to a depth H1 (H1> H2) equivalent to the inlet buffer part 46.

In the fuel cell 70 configured as described above, by providing the shallow groove region 74 a in at least a part of the outlet buffer portion 74, the pressure loss of the inlet buffer portion 46 is set smaller than the pressure loss of the outlet buffer portion 74. Yes. Therefore, when the fuel gas is consumed by the fuel gas flow passage 44 by the power generation, the effect is obtained that the pressure loss of the pressure drop and the outlet buffer 74 of the inlet buffer 46 equally ing.

Figure 9 is a front view showing a second separator (anode side separator) 80 of a fuel cell according to the implementation embodiments of the present invention.

  The second separator 80 includes an inlet buffer portion 82 that communicates with the inlet side of the fuel gas passage 44 and an outlet buffer portion 84 that communicates with the outlet side of the fuel gas passage 44.

  The inlet buffer portion 82 has a plurality of groove portions 82b through bent and linear projection portions 82a. The outlet buffer portion 84 has a plurality of groove portions 84b via linear and substantially triangular projection portions 84a that are similarly bent. By setting the groove part width S1 of the groove part 82b to be wider (S1> S2) than the groove part width S2 of the groove part 84b, the pressure loss of the inlet buffer part 82 is set smaller than the pressure loss of the outlet buffer part 84.

In this embodiment configured as described above, the groove portion 82b of the inlet buffer portion 82 is set to be wider than the groove portion 84b of the outlet buffer portion 84, so that the pressure loss of the inlet buffer portion 82 is reduced by the outlet buffer portion. The pressure loss is set to be smaller than 84. Therefore, when the fuel gas is consumed by the fuel gas flow passage 44 by the power generation, the effect is obtained that the pressure loss of the pressure drop and the outlet buffer 84 of the inlet buffer 82 is equally ing.

DESCRIPTION OF SYMBOLS 10, 60, 70 ... Fuel cell 14 ... Electrolyte membrane electrode assembly 16, 18, 62, 72, 80 ... Separator 20a ... Oxidant gas inlet communication hole 20b ... Oxidant gas outlet communication hole 22a ... Cooling medium inlet communication hole 22b ... Cooling medium outlet communication hole 24a ... Fuel gas inlet communication hole 24b ... Fuel gas outlet communication hole 26 ... Solid polymer electrolyte membrane 28 ... Cathode side electrode 30 ... Anode side electrode 32 ... Oxidant gas flow path 32a, 38a, 44a ... Linear protrusions 32b, 38b, 44b ... Linear flow channel 34, 40, 46, 66, 82 ... Inlet buffer part 36, 42, 48, 74, 84 ... Outlet buffer part
66a ... deep groove region 74a ... shallow groove region 82b, 84b ... groove portion

Claims (1)

An electrolyte membrane / electrode structure provided with a pair of electrodes on both sides of the electrolyte membrane and a separator are stacked to form a reaction gas channel for supplying a reaction gas along the electrode surface. A fuel cell provided with an inlet buffer portion communicating with an inlet side and an outlet buffer portion communicating with an outlet side of the reaction gas flow path,
The reaction gas channel has a plurality of linear channel grooves formed between a plurality of linear protrusions,
The inlet buffer portion and the outlet buffer portion have a plurality of grooves via protrusions ,
A part of the protrusions of the inlet buffer part and the outlet buffer part is provided continuously with a part of the linear protrusion part of the reaction gas flow path,
The fuel cell according to claim 1, wherein the groove width of the inlet buffer portion is set wider than the groove width of the outlet buffer portion.

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