JP6071680B2 - Operation method of fuel cell stack - Google Patents

Description

The present invention, the first separator, a first electrolyte electrode assembly, the second separator, to a method of operating a fuel cell stack to provide a plurality of power generating units being laminated in this order of the second electrolyte electrode assembly and the third separator .

  For example, in a polymer electrolyte fuel cell, an electrolyte membrane / electrode structure (MEA) provided with an anode electrode on one side and a cathode electrode on the other side of an electrolyte membrane made of a polymer ion exchange membrane is provided as a pair. It is pinched by the separator. A plurality of fuel cells are usually stacked to form a fuel cell stack, and the fuel cell stack is mounted on, for example, a fuel cell electric vehicle.

  In the fuel cell described above, a fuel gas flow path is provided in the surface of one separator so as to flow the fuel gas so as to face the anode electrode, and oxidation is performed in the surface of the other separator so as to face the cathode electrode. An oxidant gas flow path for flowing the agent gas is provided. Furthermore, between the separators, a cooling medium flow path for flowing the cooling medium is provided along the surface direction of the separator.

  By the way, the fuel cell stack may adopt a so-called thinning cooling structure in which a cooling medium flow path is formed between a predetermined number of power generation cells (unit cells). For example, as disclosed in Patent Document 1 shown in FIG. 9, the fuel cell having this type of thinning cooling structure includes a first separator 1, a first cell 2, a second separator 3, a second cell 4, and a first cell. Three separators 5 are stacked.

  In the first cell 2, the fuel electrode 2b and the air electrode 2c are disposed on both surfaces of the solid polymer electrolyte membrane 2a. The second cell 4 is configured in the same manner as the first cell 2. A first fuel gas passage 6 a is formed between the first separator 1 and the first cell 2, and a first oxidant gas passage 7 a is formed between the second separator 3 and the first cell 2. Has been. A second fuel gas passage 6b is formed between the second separator 3 and the second cell 4, and a second oxidant gas passage 7b is formed between the third separator 5 and the second cell 4. Is formed. A cooling water passage 8 is formed between the first separator 1 and the third separator 5 adjacent to each other.

JP 2002-289223 A

  In the fuel cell, the cooling water passage 8 is provided adjacent to the first fuel gas passage 6a, and the cooling water passage 8 is provided adjacent to the second oxidant gas passage 7b. On the other hand, the second fuel gas passage 6 b and the first oxidant gas passage 7 a are provided adjacent to each other and are separated from the cooling water passage 8.

  For this reason, the first fuel gas passage 6a is likely to be cooler than the second fuel gas passage 6b, and the second oxidant gas passage 7b is likely to be cooler than the first oxidant gas passage 7a. Accordingly, water or gas humidified water generated during power generation of the fuel cell often condenses in the first fuel gas passage 6a and the second oxidant gas passage 7b having a low temperature.

  Thereby, in the first fuel gas passage 6a and the second oxidant gas passage 7b, there is a problem that the flow of the fuel gas and the oxidant gas is hindered by the generated water, and stable power generation is not performed. In particular, in the second oxidant gas passage 7b where water is generated, a larger amount of condensed water is likely to be present than in the first fuel gas passage 6a, and the above-described problem is remarkable.

In the fuel cell having this type of thinning cooling structure, the present invention satisfactorily suppresses the generation water from staying in the fuel gas flow channel and the oxidant gas flow channel that are relatively close to the cooling medium flow channel, and to provide a stable method of operating a fuel cell stack capable of reliably performing power generation.

In the fuel cell stack operating method according to the present invention , the fuel cell stack has a first electrolyte / electrode structure and a second electrolyte / electrode structure in which electrodes are disposed on both sides of the electrolyte, and the first separator, A plurality of power generation units are provided in the order of the first electrolyte / electrode structure, the second separator, the second electrolyte / electrode structure, and the third separator.

  A first fuel gas flow path is formed between the first separator and the first electrolyte / electrode structure along the power generation surface. The first fuel gas flow path is formed between the first electrolyte / electrode structure and the second separator. A first oxidant gas flow path for flowing an oxidant gas along the power generation surface is formed between the second separator and the second electrolyte / electrode structure along the power generation surface. A second fuel gas flow path for flowing the fuel gas is formed, and a second oxidant gas for flowing the oxidant gas along the power generation surface between the second electrolyte / electrode structure and the third separator. A flow path is formed. And the cooling medium flow path through which a cooling medium flows is formed between each electric power generation unit.

  In this fuel cell stack operation method, the fuel gas flow rate ratio G1 is obtained by dividing the flow rate of the fuel gas supplied to the first fuel gas flow path by the flow rate of the fuel gas supplied to the second fuel gas flow path. And an oxidant gas flow rate ratio G2 obtained by dividing the flow rate of the oxidant gas supplied to the second oxidant gas flow channel by the flow rate of the oxidant gas supplied to the first oxidant gas flow channel is 1. The relationship of <G1 <G2 is set and the power generation operation is performed.

  According to the present invention, the fuel gas flow rate ratio G1 and the oxidant gas flow rate ratio G2 are set to satisfy the relationship 1 <G1 <G2. Therefore, more fuel gas is supplied to the first fuel gas channel close to the cooling medium channel than to the second fuel gas channel spaced from the cooling medium channel, and the first fuel gas channel It is possible to prevent the generated water from staying in the tank.

  Similarly, more oxidant gas is supplied to the second oxidant gas flow channel adjacent to the cooling medium flow channel than the first oxidant gas flow channel separated from the cooling medium flow channel, and the second oxidation gas flow channel is supplied. It is possible to prevent the generated water from staying in the agent gas flow path.

  In addition, since the second oxidant gas flow path in which the generated water is more likely to stay than the first fuel gas flow path is set to an oxidant gas flow rate ratio G2 larger than the fuel gas flow rate ratio G1, the second oxidant The discharge of the generated water from the gas flow path is more reliably performed, and the retention of the generated water is satisfactorily suppressed. Thereby, it is possible to satisfactorily prevent the generated water from staying in the first fuel gas flow channel and the second oxidant gas flow channel that are relatively close to the cooling medium flow channel, thereby ensuring stable power generation. It becomes possible to do.

It is a principal part disassembled perspective explanatory drawing of the electric power generation unit which comprises the fuel cell stack which concerns on the 1st Embodiment of this invention. FIG. 2 is a sectional view of the fuel cell stack taken along line II-II in FIG. 1. It is front explanatory drawing of the 1st separator which comprises the said electric power generation unit. It is explanatory drawing of one surface of the 2nd separator which comprises the said electric power generation unit. It is explanatory drawing of the other surface of the said 2nd separator. It is front explanatory drawing of the 3rd separator which comprises the said electric power generation unit. It is a principal part disassembled perspective explanatory drawing of the electric power generation unit which comprises the fuel cell stack concerning the 2nd Embodiment of this invention. It is principal part cross-sectional explanatory drawing of the fuel cell stack concerning the 3rd Embodiment of this invention. It is explanatory drawing of the fuel cell which has the thinning | cooling cooling structure currently disclosed by patent document 1. FIG.

  As shown in FIGS. 1 and 2, the fuel cell stack 10 according to the first embodiment of the present invention moves a plurality of power generation units 12 along the horizontal direction (arrow A direction) or the gravity direction (arrow C direction). Laminate each other.

  Each power generation unit 12 includes a first separator 14, a first electrolyte membrane / electrode structure (electrolyte / electrode structure) (MEA) 16 a, a second separator 18, a second electrolyte membrane / electrode structure 16 b, and a third separator 20. Is provided.

  The 1st separator 14, the 2nd separator 18, and the 3rd separator 20 are comprised, for example with the steel plate, the stainless steel plate, the aluminum plate, the plating treatment steel plate, or the metal plate which gave the surface treatment for anticorrosion to the metal surface. The 1st separator 14, the 2nd separator 18, and the 3rd separator 20 have cross-sectional uneven | corrugated shape by pressing a metal thin plate into a waveform. In addition, you may comprise the 1st separator 14, the 2nd separator 18, and the 3rd separator 20 with a carbon separator, for example.

  The first electrolyte membrane / electrode structure 16a and the second electrolyte membrane / electrode structure 16b include, for example, a solid polymer electrolyte membrane 22 in which a perfluorosulfonic acid thin film is impregnated with water, and the solid polymer electrolyte membrane 22. An anode electrode 24 and a cathode electrode 26 are provided. The solid polymer electrolyte membrane 22 has a larger planar dimension than the planar dimension of the anode electrode 24 and the cathode electrode 26.

  In the first electrolyte membrane / electrode structure 16a and the second electrolyte membrane / electrode structure 16b, the anode electrode 24 and the cathode electrode 26 may be set to the same planar dimensions as the solid polymer electrolyte membrane 22, One of the anode electrode 24 and the cathode electrode 26 may constitute a so-called step MEA having a smaller planar dimension than the solid polymer electrolyte membrane 22.

  The anode electrode 24 and the cathode electrode 26 are formed by uniformly applying 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 to the surface of the gas diffusion layer. And an electrode catalyst layer (not shown) to be formed. The electrode catalyst layers are formed on both surfaces of the solid polymer electrolyte membrane 22, for example.

  As shown in FIG. 1, an oxidation for supplying an oxidant gas, for example, an oxygen-containing gas, communicates with each other in the arrow A direction at one end edge in the long side direction (arrow B direction) of the power generation unit 12. An agent gas inlet communication hole 30a and a fuel gas outlet communication hole 32b for discharging a fuel gas, for example, a hydrogen-containing gas, are provided with a cooling medium inlet communication hole 34a for supplying a cooling medium interposed therebetween.

  The other end edge in the long side direction (arrow B direction) of the power generation unit 12 communicates with each other in the arrow A direction, and discharges the fuel gas inlet communication hole 32a for supplying fuel gas and the oxidant gas. An oxidant gas outlet communication hole 30b is provided to sandwich the cooling medium outlet communication hole 34b for discharging the cooling medium.

  As shown in FIGS. 1 and 3, the surface 14a of the first separator 14 facing the first electrolyte membrane / electrode structure 16a is connected to the fuel gas inlet communication hole 32a and the fuel gas outlet communication hole 32b. A fuel gas flow path 36 is provided. The first fuel gas channel 36 has, for example, a plurality of linear grooves extending in the arrow B direction. The first fuel gas passage 36 may have a curved portion or a bent portion, and may be a wave-like passage or a serpentine passage. The same applies to other fuel gas passages and oxidant gas passages described below.

  The first fuel gas flow path 36 and the fuel gas inlet communication hole 32a communicate with each other via a first inlet communication path (so-called bridge portion) 40a formed between the plurality of convex portions 38a. The passage number Na1 of the first inlet communication passage 40a is set to, for example, five, and each first inlet communication passage 40a has a width dimension h1 along the width direction (arrow C direction) intersecting the gas flow direction. Set to

  The first fuel gas flow path 36 and the fuel gas outlet communication hole 32b communicate with each other via a first outlet communication path (so-called bridge portion) 40b formed between the plurality of convex portions 38b. The number of passages Na1 of the first outlet communication passages 40b is set to 5, for example, and each first outlet communication passage 40b is set to the width dimension h1. The first inlet communication path 40a and the first outlet communication path 40b may have different numbers of paths and cross-sectional areas. The same applies hereinafter.

  The convex portions 38 a and 38 b may be formed integrally with a first seal member 60 described later, or a separate body may be joined to the first seal member 60. In addition, each convex-shaped part demonstrated below is comprised similarly.

  A part of the cooling medium flow path 44 that connects the cooling medium inlet communication hole 34 a and the cooling medium outlet communication hole 34 b is formed on the surface 14 b of the first separator 14.

  As shown in FIG. 4, the surface 18a of the second separator 18 facing the first electrolyte membrane / electrode structure 16a is connected to the oxidant gas inlet communication hole 30a and the oxidant gas outlet communication hole 30b. An agent gas channel 46 is formed. The first oxidizing gas channel 46 has a plurality of grooves extending in the direction of arrow B.

  The first oxidant gas flow path 46 and the oxidant gas inlet communication hole 30a communicate with each other via a first inlet communication path (so-called bridge portion) 50a formed between the plurality of convex portions 48a. The number of passages Nc1 of the first inlet communication passages 50a is set to, for example, four, and each first inlet communication passage 50a is set to the width dimension h2.

  The first oxidant gas flow path 46 and the oxidant gas outlet communication hole 30b communicate with each other via a first outlet communication path (so-called bridge portion) 50b formed between the plurality of convex portions 48b. The number of passages Nc1 of the first outlet communication passages 50b is set to, for example, four, and each first outlet communication passage 50b is set to the width dimension h2.

  As shown in FIGS. 1 and 5, the second separator 18 has a second surface 18b that faces the second electrolyte membrane / electrode structure 16b, and the fuel gas inlet communication hole 32a and the fuel gas outlet communication hole 32b communicate with each other. A fuel gas channel 52 is provided. The second fuel gas flow path 52 has, for example, a plurality of grooves extending in the direction of arrow B.

  The second fuel gas flow path 52 and the fuel gas inlet communication hole 32a communicate with each other via a second inlet communication path (so-called bridge portion) 56a formed between the plurality of convex portions 54a. The number of passages Na2 of the second inlet communication passages 56a is set to, for example, four, and each second inlet communication passage 56a is set to the width dimension h1.

  The first fuel gas flow path 36 and the fuel gas outlet communication hole 32b communicate with each other via a second outlet communication path (so-called bridge portion) 56b formed between the plurality of convex portions 54b. The number of passages Na2 of the second outlet communication passages 56b is set to, for example, four, and each second outlet communication passage 56b is set to the width dimension h1. The number of passages of the second outlet communication passage 56b may be set to be the same as the number of passages of the first outlet communication passage 40b.

  As shown in FIGS. 3 and 5, the passage number Na1 of the first inlet communication passage 40a and the passage number Na2 of the second inlet communication passage 56a are set to a relationship of Na1 / Na2 = 1.25. Similarly, the passage number Na1 of the first outlet communication passage 40b and the passage number Na2 of the second outlet communication passage 56b are set to have a relationship of Na1 / Na2 = 1.25. Thereby, a fuel gas flow rate ratio G1 (> 1) is set by dividing the flow rate of the fuel gas supplied to the first fuel gas flow channel 36 by the flow rate of the fuel gas supplied to the second fuel gas flow channel 52. The In the first embodiment, the first fuel gas channel 36 and the second fuel gas channel 52 are set to have the same number of channels or ± 1 and the channel length and the channel cross-sectional area are equal.

  As shown in FIG. 6, the surface 20a of the third separator 20 facing the second electrolyte membrane / electrode structure 16b is connected to the oxidant gas inlet communication hole 30a and the oxidant gas outlet communication hole 30b. An agent gas flow path 58 is formed. The second oxidizing gas channel 58 has a plurality of grooves extending in the direction of arrow C.

  The second oxidant gas flow path 58 and the oxidant gas inlet communication hole 30a communicate with each other via a second inlet communication path (so-called bridge portion) 62a formed between the plurality of convex portions 60a. The number of passages Nc2 of the second inlet communication passages 62a is set to, for example, six, and each second inlet communication passage 62a is set to the width dimension h2.

  The second oxidant gas flow path 58 and the oxidant gas outlet communication hole 30b communicate with each other via a second outlet communication path (so-called bridge portion) 62b formed between the plurality of convex portions 60b. The number Nc2 of passages of the second outlet communication passages 62b is set to, for example, six, and each second outlet communication passage 62b is set to the width dimension h2. The number of passages of the second outlet communication passage 62b may be set to be the same as the number of passages of the first outlet communication passage 50b.

  As shown in FIGS. 4 and 6, the passage number Nc2 of the second inlet communication passage 62a and the passage number Nc1 of the first inlet communication passage 50a are set to a relationship of Nc2 / Nc1 = 1.5. Similarly, the passage number Nc2 of the second outlet communication passage 62b and the passage number Nc1 of the first outlet communication passage 50b are set to a relationship of Nc2 / Nc1 = 1.5. Thereby, the flow rate of the fuel gas supplied to the second oxidant gas flow path 58 is divided by the flow rate of the oxidant gas supplied to the first oxidant gas flow path 46, and the oxidant gas flow rate ratio G2 (> 1). ) Is set. The fuel gas flow rate ratio G1 and the oxidant gas flow rate ratio G2 are set to satisfy the relationship 1 <G1 <G2.

  A part of the cooling medium flow path 44 is formed on the surface 20 b of the third separator 20. The surface 14b of the first separator 14 and the surface 20b of the third separator 20 overlap each other, whereby the cooling medium flow path 44 is formed.

  As shown in FIGS. 1 to 3, the first seal member 60 is integrally formed on the surfaces 14 a and 14 b of the first separator 14 around the outer peripheral edge of the first separator 14. As shown in FIGS. 1, 2, 4, and 5, the second seal member 62 is integrally formed on the surfaces 18 a and 18 b of the second separator 18 around the outer peripheral edge of the second separator 18. Is done. A third seal member 64 is integrally formed on the surfaces 20a and 20b of the third separator 20 around the outer peripheral edge of the third separator 20 (see FIGS. 1, 2 and 6).

  When the power generation units 12 are stacked on each other, a cooling medium flow path 44 is formed between the first separator 14 constituting one power generation unit 12 and the third separator 20 constituting the other power generation unit 12. Formed (see FIG. 1 and FIG. 2).

  The operation of the fuel cell stack 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 30a, and a fuel gas such as a hydrogen-containing gas is supplied to the fuel gas inlet communication hole 32a. Further, a cooling medium such as pure water, ethylene glycol, or oil is supplied to the cooling medium inlet communication hole 34a.

  For this reason, the oxidant gas is introduced from the oxidant gas inlet communication hole 30 a into the first oxidant gas flow path 46 of the second separator 18 and the second oxidant gas flow path 58 of the third separator 20. The oxidant gas moves in the direction of arrow B (horizontal direction) along the first oxidant gas flow path 46 and is supplied to the cathode electrode 26 of the first electrolyte membrane / electrode structure 16a. Similarly, the oxidant gas moves in the direction of arrow B along the second oxidant gas flow path 58 and is supplied to the cathode electrode 26 of the second electrolyte membrane / electrode structure 16b.

  On the other hand, the fuel gas is introduced into the first fuel gas channel 36 of the first separator 14 and the second fuel gas channel 52 of the second separator 18 from the fuel gas inlet communication hole 32a. The fuel gas moves in the direction of arrow B along the first fuel gas flow path 36 and is supplied to the anode electrode 24 of the first electrolyte membrane / electrode structure 16a. Similarly, the fuel gas moves in the direction of arrow B along the second fuel gas channel 52 and is supplied to the cathode electrode 26 of the second electrolyte membrane / electrode structure 16b.

  Thus, in the first electrolyte membrane / electrode structure 16a and the second electrolyte membrane / electrode structure 16b, the oxidant gas supplied to the cathode electrode 26 and the fuel gas supplied to the anode electrode 24 are converted into an electrode catalyst. Electricity is generated by being consumed by electrochemical reaction in the layer.

  Subsequently, the oxidant gas consumed by being supplied to the cathode electrodes 26 of the first electrolyte membrane / electrode structure 16a and the second electrolyte membrane / electrode structure 16b is moved along the arrow A along the oxidant gas outlet communication hole 30b. Discharged in the direction.

  The fuel gas supplied to and consumed by the anode electrodes 24 of the first electrolyte membrane / electrode structure 16a and the second electrolyte membrane / electrode structure 16b is discharged to the fuel gas outlet communication hole 32b.

  On the other hand, the cooling medium supplied to the cooling medium inlet communication hole 34 a is the cooling formed between the first separator 14 constituting one power generation unit 12 and the third separator 20 constituting the other power generation unit 12. It is introduced into the medium flow path 44. This cooling medium flows in the direction of arrow B, cools the first electrolyte membrane / electrode structure 16a and the second electrolyte membrane / electrode structure 16b, and then is discharged to the cooling medium outlet communication hole 34b.

  In this case, in the first embodiment, as shown in FIGS. 3 and 5, the passage number Na1 of the first inlet communication passage 40a is set to be larger than the passage number Na2 of the second inlet communication passage 56a. . That is, a fuel gas flow rate ratio G1 (> 1) is set by dividing the flow rate of the fuel gas supplied to the first fuel gas flow channel 36 by the flow rate of the fuel gas supplied to the second fuel gas flow channel 52. Yes.

  Therefore, as shown in FIG. 2, more fuel gas is contained in the first fuel gas passage 36 adjacent to the cooling medium passage 44 than in the second fuel gas passage 52 spaced from the cooling medium passage 44. Have been supplied. As a result, it is possible to reliably suppress a large amount of generated water from staying in the first fuel gas channel 36 as compared to the second fuel gas channel 52.

  On the other hand, as shown in FIGS. 4 and 6, the passage number Nc1 of the first inlet communication passage 50a is set to be smaller than the passage number Nc2 of the second inlet communication passage 62a. That is, an oxidant gas flow rate ratio G2 (> 1) obtained by dividing the flow rate of the oxidant gas supplied to the second oxidant gas flow channel 58 by the flow rate of the oxidant gas supplied to the first oxidant gas flow channel 46. ) Is set.

  For this reason, as shown in FIG. 2, the second oxidant gas flow path 58 adjacent to the cooling medium flow path 44 has more in the second oxidant gas flow path 46 than the first oxidant gas flow path 46 separated from the cooling medium flow path 44. Oxidant gas is supplied. Therefore, it is possible to reliably suppress a large amount of generated water from staying in the second oxidant gas flow path 58 as compared with the first oxidant gas flow path 46.

  Moreover, the fuel gas flow rate ratio G1 and the oxidant gas flow rate ratio G2 are set to have a relationship of G1 <G2. Thereby, the second oxidant gas flow path 58 in which the generated water is more likely to stay than the first fuel gas flow path 36 is more reliably discharged of the generated water from the second oxidant gas flow path 58, The retention of the generated water is suppressed satisfactorily. For this reason, it is possible to satisfactorily suppress the generation water from being retained in the first fuel gas flow path 36 and the second oxidant gas flow path 58 that are relatively close to the cooling medium flow path 44, respectively. An effect is obtained that power generation can be performed reliably.

  In the first embodiment, for example, as shown in FIGS. 3 and 5, the first inlet communication passage 40a and the second inlet communication passage 56a are set to the same width dimension (passage width) h1. In addition, the number of passages Na1 and the number of passages Na2 are different from each other. Instead, the first inlet communication passage 40a and the second inlet communication passage 56a may have the same number of passages, and the width dimension or the passage depth may be set to different values.

  The second inlet communication passage 56a uses a plurality of convex portions 38a identical to the first inlet communication passage 40a, and closes one groove portion between the convex portions 38a to provide the four second inlet passages. You may comprise the communicating path 56a. On the other hand, the oxidant gas side can be configured similarly to the fuel gas side described above.

  Furthermore, the reactive gas flow path may be provided with a reactive gas rectifying buffer located outside the power generation region. At this time, in the reaction gas flow channel on the side close to the cooling medium flow channel 44, the area ratio and flow rate ratio of the buffer portion are set with respect to the reaction gas flow channel on the side separated from the cooling medium flow channel 44. Can do. Thereby, the staying state of the generated water in each reaction gas channel is made uniform, and it becomes possible to suppress a decrease in power generation performance.

  FIG. 7 is an exploded perspective view of a main part of the power generation unit 72 constituting the fuel cell stack 70 according to the second embodiment of the present invention. The same components as those of the fuel cell stack 10 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. Similarly, in the third embodiment described below, detailed description thereof is omitted.

  The power generation unit 72 includes a first separator 74, a first electrolyte membrane / electrode structure 16 a, a second separator 76, a second electrolyte membrane / electrode structure 16 b, and a third separator 78.

  A first fuel gas flow path 36a is provided on the surface 74a side of the first separator 74 facing the first electrolyte membrane / electrode structure 16a. The first fuel gas flow path 36a and the fuel gas inlet communication hole 32a communicate with each other via an inlet communication path (so-called bridge portion) 82a formed between the plurality of convex portions 80a. The first fuel gas flow path 36a and the fuel gas outlet communication hole 32b communicate with each other via an outlet communication path (so-called bridge portion) 82b formed between the plurality of convex portions 80b.

  A second fuel gas passage 52a is provided on the surface 76b side of the second separator 76 facing the second electrolyte membrane / electrode structure 16b. The second fuel gas flow path 52a and the fuel gas inlet communication hole 32a communicate with each other via an inlet communication path 82a formed between the plurality of convex portions 80a. The second fuel gas flow path 52a and the fuel gas outlet communication hole 32b communicate with each other via an outlet communication passage 82b formed between the plurality of convex portions 80b.

  The number of channel grooves Na3 of the first fuel gas channel 36a is set to be larger than the number of channel grooves Na4 of the second fuel gas channel 52a, for example, Na3 = Na4 + 1. Therefore, a fuel gas flow rate ratio G1 (> 1) is set by dividing the flow rate of the fuel gas supplied to the first fuel gas flow channel 36a by the flow rate of the fuel gas supplied to the second fuel gas flow channel 52a. The

  A first oxidant gas flow path 46a is provided on a surface 76a of the second separator 76 facing the first electrolyte membrane / electrode structure 16a. The first oxidant gas flow path 46a and the oxidant gas inlet communication hole 30a communicate with each other via an inlet communication path (so-called bridge portion) 86a formed between the plurality of convex portions 84a. The first oxidant gas passage 46a and the oxidant gas outlet communication hole 30b communicate with each other via an outlet communication path (so-called bridge portion) 86b formed between the plurality of convex portions 84b.

  On the surface 78a side of the third separator 78 facing the second electrolyte membrane / electrode structure 16b, a second oxidizing gas channel 58a is provided. The second oxidant gas flow path 58a and the oxidant gas inlet communication hole 30a communicate with each other via an inlet communication path 86a formed between the plurality of convex portions 84a. The second oxidant gas flow path 58a and the oxidant gas outlet communication hole 30b communicate with each other via an outlet communication path 86b formed between the plurality of convex portions 84b.

  The channel groove number Nc3 of the first oxidant gas channel 46a is set to a smaller number than the channel groove number Nc4 of the second oxidant gas channel 58a, for example, Nc3 = Nc4-3. Therefore, the oxidant gas flow rate ratio G2 (> 1) obtained by dividing the flow rate of the oxidant gas supplied to the first oxidant gas flow channel 46a by the flow rate of the oxidant gas supplied to the second oxidant gas flow channel 58a. ) Is set. Further, the fuel gas flow rate ratio G1 and the oxidant gas flow rate ratio G2 are set to have a relationship of 1 <G1 <G2.

  In the second embodiment configured as described above, the number of flow channel grooves Na3 of the first fuel gas flow channel 36a is set to be larger than the number of flow channel grooves Na4 of the second fuel gas flow channel 52a. The fuel gas flow ratio G1 (> 1) is set. Similarly, the number of channel grooves Nc3 of the first oxidant gas channel 46a is set to be smaller than the number of channel grooves Nc4 of the second oxidant gas channel 58a, so that the oxidant gas flow ratio G2 ( > 1) is set. Further, the fuel gas flow rate ratio G1 and the oxidant gas flow rate ratio G2 are set to satisfy the relationship 1 <G1 <G2.

  As a result, the flow rates of the first fuel gas flow path 36a and the second oxidant gas flow path 58a, in which the generated water tends to stay, are increased, and the stay of the generated water can be suppressed. Moreover, the first fuel gas flow path 36a and the second oxidant gas flow path 58a can satisfactorily suppress the retention of the generated water, and can stably perform power generation. The same effect as the first embodiment is obtained.

  FIG. 8 is an explanatory cross-sectional view of a main part of the fuel cell stack 100 according to the third embodiment of the present invention.

  The power generation unit 102 constituting the fuel cell stack 100 includes a first separator 104, a first electrolyte membrane / electrode structure 16a, a second separator 106, a second electrolyte membrane / electrode structure 16b, and a third separator 108.

  A first fuel gas flow path 36b is provided on the surface 104a side of the first separator 104 facing the first electrolyte membrane / electrode structure 16a. The first fuel gas channel 36b and the fuel gas inlet communication hole, and the first fuel gas channel 36b and the fuel gas outlet communication hole are, for example, the same inlet communication channel (not shown) as in the second embodiment. And it communicates via an exit communicating path.

  A second fuel gas channel 52b is provided on the surface 106b side of the second separator 106 facing the second electrolyte membrane / electrode structure 16b. The second fuel gas channel 52b and the fuel gas inlet communication hole, and the second fuel gas channel 52b and the fuel gas outlet communication hole are, for example, the same inlet communication channel (not shown) as in the second embodiment. And it communicates via an exit communicating path.

  A first oxidant gas flow path 46b is provided on the surface 106a of the second separator 106 facing the first electrolyte membrane / electrode structure 16a. The first oxidant gas flow path 46b and the oxidant gas inlet communication hole, and the first oxidant gas flow path 46b and the oxidant gas outlet communication hole are, for example, the same inlet communication path as in the second embodiment ( (Not shown) and the outlet communication passage.

  A second oxidant gas flow path 58b is provided on the surface 108a side of the third separator 108 facing the second electrolyte membrane / electrode structure 16b. The second oxidant gas flow path 58b and the oxidant gas inlet communication hole, and the second oxidant gas flow path 58b and the oxidant gas outlet communication hole are, for example, the same inlet communication path as in the second embodiment ( (Not shown) and the outlet communication passage.

  The second separator 106 is set to a flow path height lower than the flow path height of the first separator 104 and the third separator 108. The first separator 104 has a flow path height D1 in the stacking direction (arrow A direction), the third separator 108 has a flow path height D2 in the stacking direction, while the second separator 106 has the stacking direction. It has a channel height D3 in the direction. The relationship of channel height D1≈channel height D2> channel height D3 is set, and more preferably, the relationship of channel height D2> channel height D1> channel height D3 is set. For this reason, the fuel gas flow rate ratio G1 and the oxidant gas flow rate ratio G2 are set to satisfy the relationship 1 <G1 <G2. What is necessary is just to adjust the pressure loss between communicating holes so that it may be set to said relationship.

  In the third embodiment configured as described above, the flow rates of the first fuel gas flow path 36b and the second oxidant gas flow path 58b in which the generated water is likely to stay are increased to suppress the retention of the generated water. Can do. In addition, the first fuel gas flow path 36b and the second oxidant gas flow path 58b can satisfactorily suppress the retention of the generated water, and stable power generation can be reliably performed. The same effects as those of the first and second embodiments are obtained.

10, 70, 100 ... Fuel cell stacks 12, 72, 102 ... Power generation units 14, 18, 20, 74, 76, 78, 104, 106, 108 ... Separator 16a, 16b ... Electrolyte membrane / electrode structure 22 ... Solid height Molecular electrolyte membrane 24 ... Anode electrode 26 ... Cathode electrode 30a ... Oxidant gas inlet communication hole 30b ... Oxidant gas outlet communication hole 32a ... Fuel gas inlet communication hole 32b ... Fuel gas outlet communication hole 34a ... Cooling medium inlet communication hole 34b ... Cooling medium outlet communication holes 36, 36a, 36b, 52, 52a, 52b ... fuel gas flow paths 38a, 38b, 48a, 48b, 54a, 54b, 60a, 60b, 80a, 80b, 84a, 84b ... convex portions 40a, 50a, 56a, 62a, 82a, 86a ... Inlet communication passages 40b, 50b, 56b, 62b, 82b, 86b ... Outlet communication Passage 44: Cooling medium flow path 46, 46a, 46b, 58, 58a, 58b ... Oxidant gas flow path

Claims (1)

A first separator / electrode structure and a second electrolyte / electrode structure having electrodes disposed on both sides of the electrolyte, the first separator, the first electrolyte / electrode structure, the second separator, and the second electrolyte A plurality of power generation units stacked in the order of an electrode structure and a third separator are provided, and a first fuel gas flows between the first separator and the first electrolyte / electrode structure along the power generation surface. A fuel gas flow path is formed, and a first oxidant gas flow path for flowing an oxidant gas along the power generation surface is formed between the first electrolyte / electrode structure and the second separator, Between the second separator and the second electrolyte / electrode structure, there is formed a second fuel gas flow path for flowing the fuel gas along the power generation surface, and the second electrolyte / electrode structure and the second 3 separators along the power generation surface Together with the second oxidant gas passage for flowing a serial oxidant gas is formed, between each of the power generation unit, a method of operating a fuel cell stack cooling medium flow path is formed to flow a cooling medium,
A fuel gas flow ratio G1 obtained by dividing a flow rate of the fuel gas supplied to the first fuel gas flow path by a flow rate of the fuel gas supplied to the second fuel gas flow path, and the second oxidant gas An oxidant gas flow rate ratio G2 obtained by dividing the flow rate of the oxidant gas supplied to the flow path by the flow rate of the oxidant gas supplied to the first oxidant gas flow path satisfies 1 <G1 <G2. An operation method of a fuel cell stack, characterized in that the power generation operation is set in the relationship.

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