Fuel cell stack

Abstract

Fuel cell stack (10), comprising: a plurality of stacked power generation cells (100); and a dummy cell (200) which, of the two end portions of the power generation cells, is arranged at the end portion on an upstream side in a direction in which a reaction gas supplied to the fuel cell stack (10) flows, and which does not generate power, wherein: the fuel cell stack (10) has a reaction gas supply manifold (410, 420) passing through the power generation cells (100) and the dummy cell (200); the power generation cell (100) has a plurality of first introduction flow paths (110, 120a to 120e) arranged along a gravity direction for supplying the reaction gas from the reaction gas supply manifold (410, 420) to a power generation reaction; the dummy cell (200) has a plurality of second introduction flow paths (220a to 220e) arranged along the direction of gravity for supplying the reaction gas from the reaction gas supply manifold (410, 420) to a central region (250); and the fuel cell stack (10) has at least one of: a first configuration in which a flow path width (W6) of the second introduction flow path (220a) at a lowermost end of the second introduction flow paths in the direction of gravity is narrower than an average flow path width of the second introduction flow paths; and a second configuration in which a flow path width (W11) of the first introduction flow path (120a) at a lowermost end of the first introduction flow paths in the direction of gravity is larger than an average flow path width of the first introduction flow paths.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention

[0001] The invention relates to a fuel cell stack. 2. Description of the state of the art

[0002] A fuel cell stack in which a plurality of power generation cells are stacked, and dummy cells that do not generate power are arranged on both sides in the stacking direction of the power generation cells, has been described (see, for example, JP 2015-069737 A). Other fuel cell stacks are the subject of US 2004 / 0 265 667 A1 and JP 2000-149977 A. BACKGROUND OF THE INVENTION

[0003] When liquid water flows into a feed manifold for reactant gas to be supplied to a fuel cell, the liquid water flows toward the bottom of the feed manifold in the direction of gravity. In this case, the liquid water may overflow the dummy cell and intensively penetrate a specific power generation cell, causing problems such as the inability to supply the reactant gas and the inability of the power generation cell to generate sufficient power.

[0004] One aspect of the invention relates to a fuel cell stack comprising: a plurality of stacked power generation cells; and a dummy cell that, of both end portions of the power generation cells, is arranged at the end portion on an upstream side in a direction in which a reactant gas supplied to the fuel cell stack flows, and that does not generate power. The fuel cell stack has a reactant gas supply manifold that passes through the power generation cells and the dummy cell. The power generation cell has a plurality of first introduction flow paths arranged along a gravity direction for supplying the reactant gas from the reactant gas supply manifold to a power generation reaction. The dummy cell has a plurality of second introduction flow paths arranged along the gravity direction for supplying the reactant gas from the reactant gas supply manifold to a central region.The fuel cell stack has at least one of: a first configuration in which a flow path width of the second introduction flow path at a lowest end of the second introduction flow paths in the gravity direction is narrower than an average flow path width of the second introduction flow paths; and a second configuration in which a flow path width of the first introduction flow path at a lowest end of the first introduction flow paths in the gravity direction is larger than an average flow path width of the first introduction flow paths.

[0005] When liquid water enters the reactant gas supply manifold, the liquid water flows along the lower surface of the reactant gas supply manifold, which is located at the bottom in the gravity direction. When the reactant gas introduction flow path is clogged by the liquid water, the liquid water flows into the power generation cell or the dummy cell due to the pressure difference between the upstream and downstream sides of the reactant gas introduction flow path. According to the invention, when the first configuration is adopted, the flow path width of the second introduction flow path at the lowest end of the second introduction flow paths in the gravity direction is narrower than the average flow path width of the second introduction flow paths.Therefore, the liquid water moves more easily toward the center region of the dummy cell, and the amount of liquid water moving toward the power generation cell is reduced by the amount of liquid water moving toward the center region of the dummy cell. Therefore, the amount of liquid water moving toward the power generation region of the power generation cell, or more specifically, one or more specific power generation cells adjacent to the dummy cell, is reduced.

[0006] Furthermore, when the second configuration is adopted, the flow path width of the first introduction flow path at the lowest end of the first introduction flow paths in the gravity direction is larger than the average flow path width of the first introduction flow paths. Therefore, when the same amount of liquid water moves from the dummy cells, it is more difficult for the liquid water to block the first introduction flow paths at the lowest end in the gravity direction. In addition, since the pressure difference between the upstream and downstream sides of the reactant gas introduction flow path is relatively small, the amount of movement of the liquid water moving particularly toward the power generation region of the power generation cell can be further reduced. This means that the intensive penetration of the liquid water into the power generation region of the specific power generation cell can be prevented.

[0007] In the fuel cell stack according to the aspect, the fuel cell stack may have both the first configuration and the second configuration. According to this aspect, the movement of liquid water to the central region of the dummy cell is facilitated by the first configuration, and the movement of liquid water to the power generation region of the specific power generation cell is prevented by the second configuration. Thus, the intensive penetration of liquid water into the power generation region of the specific power generation cell can be further prevented.

[0008] In the fuel cell stack according to the aspect, the flow path width of the second introduction flow path at the lowest end in the gravity direction may be narrower than the flow path width of the first introduction flow path at the lowest end in the gravity direction. According to this aspect, it becomes easy to block the second introduction flow path at the lowest end in the gravity direction, and it becomes difficult to block the first introduction flow path at the lowest end in the gravity direction with liquid water. Therefore, liquid water easily moves to the center region of the dummy cell, and the movement of the liquid water to the power generation region of the specific power generation cell is prevented. Therefore, the intensive penetration of the liquid water into the power generation region of the specific power generation cell can be further prevented.

[0009] In the fuel cell stack according to the aspect, in the first configuration, the flow path width of the second introduction flow path at the lowermost end of the second introduction flow paths may be the narrowest width of the second introduction flow paths.

[0010] In the fuel cell stack according to the aspect, in the first configuration, regarding the flow path widths of the second introduction flow paths, the flow path widths of the second introduction flow paths arranged above the second introduction flow path at the lowest end may be determined such that the farther the second introduction flow path is from the second introduction flow path at the lowest end, the larger the flow path width of the second flow path becomes.

[0011] In the fuel cell stack according to the aspect, in the second configuration, the flow path width of the first introduction flow path at the lowest end of the first introduction flow paths may be the largest width of the first introduction flow paths.

[0012] In the fuel cell stack according to the aspect, in the second configuration, the flow path widths of the first introduction flow paths arranged above the first introduction flow path at the lowest end may be determined such that the farther the first introduction flow path is from the first introduction flow path at the lowest end, the narrower the flow path width of the first introduction flow path becomes.

[0013] According to the aspect, a fuel cell stack can be realized in various ways, and instead of a fuel cell stack, for example, a fuel cell system, a power generation cell, and a dummy cell can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The features and advantages as well as the technical and economic significance of exemplary embodiments of the invention are described below with reference to the accompanying drawings, in which like reference numerals designate like elements; in which: Fig. 1 a perspective view of a fuel cell stack; Fig. 2 is a plan view schematically showing a power generation cell; Fig. 3 is an enlarged schematic diagram for explaining a power generation cell anode gas introduction flow path; Fig. 4 is a sectional view of the power generation cell anode gas introduction flow path along the section line IV-IV in Fig. 3; Fig. 5 is a sectional view of a power generation cell reaction gas introduction flow path taken along section line VV in the Fig. 3 and Fig. 4; Fig. 6 is a plan view schematically showing a dummy cell; Fig. 7 is an enlarged schematic diagram for explaining a dummy cell anode gas introduction flow path of the dummy cell; Fig. 8 is a sectional view of the dummy cell anode gas introduction flow path of the dummy cell along the section line VIII-VIII in Fig. 7; Fig. 9 is an explanatory diagram showing moving amounts of liquid water moving to central portions of the power generation cell and the dummy cell according to a first embodiment; Fig. 10 is an explanatory diagram showing movement amounts of liquid water moving to central portions of the power generation cell and the dummy cell according to a comparative example; Fig. 11 is an explanatory diagram showing a power generation cell of a second embodiment; Fig. 12 is an enlarged schematic diagram for explaining the power generation cell anode gas introduction flow path of the power generation cell of the second embodiment; Fig. 13 is a sectional view of a power generation cell anode gas introduction flow path of a third embodiment, similar to the view in Fig. 4; and Fig. 14 is a plan view of a frame of a power generation cell of the third embodiment. BACKGROUND OF THE INVENTIONFirst Embodiment

[0015] Fig. 1 is a perspective view of a fuel cell stack 10. The fuel cell stack 10 includes a plurality of power generation cells 100, dummy cells 200, current collecting plates 300, 310, insulating plates 320, 330, and end plates 340, 350. The power generation cells 100 are stacked in the Y direction (horizontal direction) to form a stacked body. In a first embodiment, horizontal directions are referred to as the X direction and the Y direction, and a vertical direction is referred to as the Z direction. A downward direction in the vertical direction corresponds to the direction of gravity. The dummy cells 200 are arranged on both sides of the stacked body of the power generation cells 100 in the Y direction, with the power generation cells 100 interposed therebetween.The dummy cells 200 may be arranged, of the two end portions of the power generation cells 100, at the end portion on the upstream side in a direction in which a reaction gas supplied to the fuel cell stack 10 flows. The current collecting plates 300, 310 are arranged outside the dummy cells 200 in the Y direction, with the power generation cells 100 and the dummy cells 200 interposed therebetween. The insulating plates 320, 330 are arranged outside the current collecting plates 300, 310 in the Y direction, with the power generation cells 100, the dummy cells 200, and the current collecting plates 300, 310 interposed therebetween. The end plates 340, 350 are arranged outside the insulating plates 320, 330 in the Y direction, with the power generation plates 100, the dummy cells 200, the current collection plates 300, 310 and the insulating plates 320, 330 arranged therebetween.

[0016] The fuel cell stack 10 has a cathode gas supply manifold 410, a cathode gas discharge manifold 415, an anode gas supply manifold 420, an anode gas discharge manifold 425, a coolant supply manifold 430, and a coolant discharge manifold 435 passing through the power generation cells 100, the dummy cells 200, the current collecting plates 300, 310, the insulating plates 320, 330, and the end plates 340, 350. Of the manifolds, those manifolds used for supplying the reaction gas (also referred to as “reaction gas supply manifolds”, specifically including the cathode gas supply manifold 410 and the anode gas supply manifold 420) are formed at positions higher in the direction of gravity than those manifolds used for discharging the reaction gas (also referred to as “reaction gas discharge manifold”, specifically including the cathode gas discharge manifold 415 and the anode gas discharge manifold 425).

[0017] Fig. 2 is a plan view schematically showing the power generation cell 100. A central region 150 of the power generation cell 100 is a power generation region in which a membrane electrode assembly 154 is provided.The power generation cell 100 includes a power generation cell cathode gas introduction flow path 110 (also referred to as “first introduction flow path 110”) used to introduce a cathode gas from the cathode gas supply manifold 410 to the central region 150, a power generation cell cathode gas discharge flow path 115 used to discharge the cathode gas from the central region 150 to the cathode gas discharge manifold 415, a power generation cell anode gas introduction flow path 120 (also referred to as “first introduction flow path 120”) used to introduce anode gas from the anode gas supply manifold 420 to the central region 150, and a power generation cell anode gas discharge flow path 125 used to discharge the anode gas from the central region 150 to the anode gas discharge manifold 425. The structure of the power generation cell anode gas introduction flow path 120 and the like will be described later.

[0018] Fig. 3 is an enlarged schematic diagram illustrating the power generation cell anode gas introduction flow path 120. The power generation cell anode gas introduction flow path 120 includes a plurality of power generation cell anode gas introduction flow paths 120a, 120b, 120c, 120d, and 120e arranged along the gravity direction, with their flow path widths W1, W2, W3, W4, and W5 being equal. The flow path width is a width measured in the gravity direction. Furthermore, when the width of a flow path varies with respect to positions in the X direction, the average value thereof is used as the flow path width of the flow path. Further, the heights (the widths in the Y direction) of the power generation cell anode gas introduction flow paths 120a, 120b, 120c, 120d and 120e are substantially the same, and the cross-sectional areas and flow path widths are proportional to each other.Thus, in a case where the power generation cell anode gas introduction flow paths 120a, 120b, 120c, 120d, and 120e are compared with each other, their cross-sectional areas can be used instead of the flow path widths. In the case shown in . Fig. 3, the number of power generation cell anode gas introduction flow paths 120 is five, but is not limited to this, and may be two or more. If liquid water enters the anode gas supply manifold 420, it is possible that the power generation cell anode gas introduction flow path 120a is blocked at the lowest end in the gravity direction. In the example of Fig. 3, although most of the power generation cell anode gas introduction flow path 120a at the lowest end in the gravity direction is blocked with the liquid water, the power generation cell anode gas introduction flow paths 120b to 120e located above the lowest end in the gravity direction are not blocked with liquid water.

[0019] Fig. 4 is a sectional view of the power generation cell anode gas introduction flow path taken along section line IV-IV of Fig. 3. The power generation cell 100 includes a frame 160, an anode separator plate 170, and a cathode separator plate 180. The frame 160 is made of, for example, a resin and supports the membrane electrode assembly 154. The membrane electrode assembly 154 includes an electrolyte membrane 151, an anode catalyst layer 152, and a cathode catalyst layer 153. The electrolyte membrane 151 is made of an ion exchange resin membrane that exhibits good proton conductivity in a wet state. Specifically, the electrolyte membrane 151 is made of a fluororesin-based ion exchange resin membrane having a sulfonic acid group as the ion exchange group, for example, Nafion (registered trademark). The anode catalyst layer 152 and the cathode gas catalyst layer 153 each comprise carbon carrying a catalyst (for example, platinum) and an ionomer carrying, for example, a sulfonic acid group (-SO 3H). An anode gas diffusion layer 155 and a cathode gas diffusion layer 156 are disposed on the anode catalyst layer 152 and the cathode catalyst layer 153, respectively. The anode gas diffusion layer 155 and the cathode gas diffusion layer 156 are made, for example, of carbon paper or a carbon nonwoven fabric. Furthermore, the anode gas diffusion layer 155 and the cathode gas diffusion layer 156 may also be made of an expanded metal or a porous member instead of the carbon paper or the carbon nonwoven fabric.

[0020] The cathode separator plate 180 includes a protrusion 181 projecting toward the anode separator plate 170 of the adjacent cell (power generation cell 100 or dummy cell 200). The anode separator plate 170 has a receiving portion 171 at a position facing the protrusion 181. When the protrusion 181 is pressed against the receiving portion 171, a seal is formed between the cells (between the power generation cells 100 or between the power generation cell 100 and the dummy cell 200). An adhesive or a sealing member (not shown) is disposed between the protrusion 181 and the receiving portion 171.

[0021] The anode separator plate 170 has an anode gas introduction flow path forming portion 173 used to form the power generation cell anode gas introduction flow path 120, which communicates with the anode gas supply manifold 420. Although similar structures are omitted from the drawing, the anode separator plate 170 includes an anode gas discharge flow path forming portion used to form the power generation cell anode gas discharge flow path 125, which communicates with the anode gas discharge manifold 425. In addition, the cathode separator plate 180 includes a cathode gas introduction flow path forming portion and a cathode gas discharge flow path forming portion, which are used to form the power generation cell cathode gas introduction flow path 110 and the power generation cell cathode gas discharge flow path 115.

[0022] Fig. 5 is a sectional view of the power generation cell reaction gas introduction flow path taken along section line VV in the Fig. 3 and Fig. 4. The anode gas introduction flow path forming portion 173 has a protruding shape protruding from the frame 160 toward the cathode separator plate 180, and the power generation cell anode gas introduction flow paths 120a to 120e are formed between a recessed shape of the protruding shape of the anode separator plate 170 formed on the frame 160 side and the frame 160. In the first embodiment, the flow path widths W1 to W5 of the power generation cell anode gas introduction flow paths 120a to 120e are equal. Furthermore, the heights (the widths in the Y direction) of the power generation cell anode gas introduction flow paths 120a to 120e are equal.

[0023] Fig. 6 is a plan view schematically showing the dummy cell 200. The differences between the dummy cell 200 and the power generation cell 100 are that the dummy cell 200 does not have a membrane electrode assembly 154 in a central region 250, and that the flow path widths of a dummy cell cathode gas introduction flow path 210 and a dummy cell anode gas introduction flow path 220 (also referred to as a "second introduction flow path 220") are different from the flow path widths of the power generation cell cathode gas introduction flow path 110 and the power generation cell anode gas introduction flow path 120. Further, in the central region 250 of the dummy cell 200, a region in which the anode gas flows and a region in which the cathode gas flows are separated from each other by the resin forming the frame 160, so that the anode gas and the cathode gas are not mixed with each other.The flow path widths of a dummy cell cathode gas discharge path 215 and a dummy cell anode gas discharge path 225 of the dummy cell 200 are equal to the flow path widths of the power generation cell cathode gas discharge flow path 115 and the power generation cell anode gas discharge flow path 125 of the power generation cell 100.

[0024] Fig. 7 is an enlarged schematic diagram illustrating the dummy cell anode gas introduction flow path 220 of the dummy cell 200. The dummy cell anode gas introduction flow path 220 includes a plurality of dummy cell anode gas introduction flow paths 220a, 220b, 220c, 220d, and 220e arranged along the gravity direction. A flow path width W6 of the dummy cell anode gas introduction flow path 220a at the lowest end in the gravity direction is set smaller than the average flow path width of the dummy cell anode gas introduction flow paths 220a, 220b, 220c, 220d, and 220e. In the Fig. 7, the flow path widths W6, W7, W8, W9, and W10 of the dummy cell anode gas introduction flow paths 220a, 220b, 220c, 220d, and 220e are W6 < W7 < W8 < W9 < W10. That is, in the dummy cell anode gas introduction flow paths 220 (second introduction flow paths), the flow path width W6 of the dummy cell anode gas introduction flow path 220a at the lowest end in the gravity direction is narrower than the flow path width W10 of the dummy cell anode gas introduction flow path 220e at the uppermost end in the gravity direction. In addition, when the dummy cell anode gas introduction flow paths 220a, 220b, 220c, 220d, and 220e have two or more flow path widths, the dummy cell anode gas introduction flow path 220a at the lowest end in the gravity direction may have the smallest flow path width among the dummy cell anode gas introduction flow paths 220a, 220b, 220c, 220d, and 220e.Therefore, for example, there may be a case where the flow path widths W6, W7 of the dummy cell anode gas introduction flow paths 220a, 220b are the same (the flow path width in this case is referred to as Wa), the flow path widths W8, W9, W10 of the dummy cell anode gas introduction flow paths 220c, 220d, 220e are the same (the flow path width in this case is referred to as Wb), and Wa < Wb is satisfied. In the case shown in . Fig. 7, the number of dummy cell anode gas introduction flow paths 220 is five, but not limited to this, and may be two or more.

[0025] When the liquid water enters the anode gas supply manifold 420, the dummy cell anode gas introduction flow path 220a at the lowest end in the direction of gravity is blocked first. Fig. In the example shown in Figure 7, the dummy cell anode gas introduction flow path 220a at the lowest end in the gravity direction is completely blocked by liquid water. However, the dummy cell anode gas introduction flow paths 220b to 220e located above the lowest end in the gravity direction are not blocked by liquid water.

[0026] Fig. 8 is a sectional view of the dummy cell anode gas introduction flow path 220 taken along section line VIII-VIII of Fig. 7. From this, it can be seen that the flow path widths W6, W7, W8, W9, and W10 of the dummy cell anode gas introduction flow paths 220a, 220b, 220c, 220d, and 220e satisfy W6 < W7 < W8 < W9 < W10. In addition, since the dummy cell 200 has the same structure as the power generation cell 100 except that the dummy cell 200 does not have the membrane electrode assembly 154, the anode gas diffusion layer 155, and the cathode gas diffusion layer 156, the Fig. 4 corresponding representation of the sectional view of the dummy cell anode gas introduction flow path 220 is omitted.

[0027] Fig. Fig. 9 is an explanatory diagram showing the movement amounts of liquid water moving to the central portions 150, 250 of the power generation cell 100 and the dummy cell 200 in the first embodiment. Fig. 9, the illustration of the current collecting plates 300, 310, the insulating plates 320, 330, and the end plates 340, 350 is omitted. Anode gas flows from the upper right side of the fuel cell stack 10 in the direction of gravity into the anode gas supply manifold 420 and is discharged from the lower right side of the fuel cell stack 10 in the direction of gravity. The movement amounts of the liquid water moving from the anode gas supply manifold 420 to the central region 150 (power generation region) of the power generation cell 100 and to the central region 250 of the dummy cell 200 are V1, V2 (V1 < V2), respectively, and a large amount (V2) of the liquid water moves to the central region 250 of the dummy cell 200. However, a small amount (V1) of the liquid water moves to the central region 150 of the power generation cell 100.

[0028] Fig. 10 is an explanatory diagram showing the movement amounts of liquid water moving to the central region 150, 250 of the power generation cell 100 and the dummy cell 200 in a comparative example. In the comparative example, the flow path widths of the reactant gas introduction flow paths of the power generation cell 100 and the dummy cell 200 are the same, that is, W1 = W2 = W3 = W4 = W5 = W6 = W7 = W8 = W9 = W10. In the comparative example, the volumetric amounts (also referred to as "movement amounts") of liquid water moving from the anode gas supply manifold 420 to the central region 150 of the power generation cell 100 and the central region 250 of the dummy cell 200 are V3, V4, respectively. When comparing the movement amounts of the liquid water moving toward the central region 150 of the power generation cell 100, V1 < V3 holds. The reason for this is as follows: If you Fig. 3 and Fig. 7, in the first embodiment, when liquid water in a volumetric amount V enters the anode gas supply manifold 420, since the flow path width W6 of the dummy cell anode gas introduction flow path 220a at the lowest end in the gravity direction is narrower than the average flow path width of the dummy cell anode gas introduction flow paths 220a, 220b, 220c, 220d, and 220e, it becomes easier to block the dummy cell anode gas introduction flow path 220a at the lowest end in the gravity direction with liquid water. When the dummy cell anode gas introduction flow path 220a is blocked with the liquid water, the pressure of the reaction gas in the anode gas supply manifold 420 increases, the pressure difference between the inlet and outlet of the dummy cell anode gas introduction flow path 220a increases, and thus it becomes easier for the liquid water to move to the central region 250 of the dummy cell 200.The movement amount in this case is denoted as V2. As a result, the movement amount (V - V2) of the liquid water moving to a region corresponding to the anode gas supply manifold 420 of a specific power generation cell 100 adjacent to the dummy cell 200 is reduced due to the movement of the liquid water toward the central region 250 of the dummy cell 200. Furthermore, the flow path width of the power generation cell anode gas introduction flow path 120a at the lowest end in the gravity direction of the power generation cell 100 adjacent to the dummy cell 200 is equal to the flow path widths W2 to W5 of the other power generation cell anode gas introduction flow paths 120b to 120e, so that the power generation cell anode gas introduction flow path 120a is not narrowed by the liquid water and is thus less likely to be clogged.Thus, the pressure difference between the inlet and outlet of the power generation cell anode gas introduction flow path 120a is relatively small, and a small amount (the movement amount V1) of the liquid water of the movement amount (V-V2) moves to the center region 150 of the specific power generation cell 100. As a result, it becomes easy for liquid water to move to the center region 250 of the dummy cell 200, and the movement amount of the liquid water moving to the center region 150 of the power generation cell 100 is reduced. Thus, intensive intrusion of liquid water into the center region 150 of the specific power generation cell, especially the power generation cell 100 adjacent to the dummy cell 200, can be prevented.

[0029] In contrast, in the comparative example, when liquid water enters the anode gas supply manifold 420 in a volumetric amount V, since the flow path width of the dummy cell anode gas introduction flow path 220a at the lowest end in the gravity direction is not narrower than the average flow path width of the second introduction flow paths, it is difficult to block the dummy cell anode gas introduction flow path 220a at the lowest end in the gravity direction. In this case, the pressure difference between the inlet and outlet of the dummy cell anode gas introduction flow path 220a is not large, and the movement amount V4 of the liquid water moving to the dummy cell 200 is smaller than the movement amount V2 of the first embodiment.Therefore, the movement amount (V-V4) of the liquid water moving toward the anode gas supply manifold 420 of the power generation cell 100 adjacent to a dummy cell 200 is greater than the movement amount (V-V2) of the liquid water in the first embodiment. Therefore, the movement amount V3 of the liquid water moving toward the central region 150 of the power generation cell 100 becomes greater than the movement amount V1 of the liquid water in the first embodiment. That is, the movement amount V1 of the liquid water moving toward the central region 150 of the specific power generation cell 100 of the first embodiment is smaller than the movement amount V3 of the liquid water in the comparative example.

[0030] As described above, according to the first embodiment, a configuration (first configuration) is proposed in which the flow path width W6 of the dummy cell anode gas introduction flow path 220a at the lowest end in the gravity direction is narrower than the average flow path width of the dummy cell anode gas introduction flow paths 220a, 220b, 220c, 220d, and 220e. Therefore, the movement amount V2 of the liquid water moving to the central region 250 of the dummy cell 200 is relatively large, and the movement amount V1 of the liquid water moving to the central region 150 of the specific power generation cell 100 can be relatively reduced. Accordingly, intensive intrusion of liquid water into the central region 150 of the specific power generation cell 100 can be prevented. Second embodiment

[0031] Fig. 11 is an explanatory diagram showing the power generation cell 100 of a second embodiment. Fig. 12 is an enlarged schematic diagram for explaining the power generation cell anode gas introduction flow path 120 of the power generation cell 100 of the second embodiment. The differences from the first embodiment are that, although the flow path widths W1 to W5 of the power generation cell anode gas introduction flow paths 120a to 120e are the same as in the first embodiment, in the second embodiment, a flow path width W11 of the power generation cell anode gas introduction flow path 120a at the lowest end in the gravity direction is set larger than the average flow path width of the power generation cell anode gas introduction flow paths 120a to 120e. In the example in Fig. 12 applies to the flow path widths W11 to W15 of the power generation cell anode gas introduction flow paths 120a to 120e, W11 > W12 > W13 > W14 > W15. That is, the flow path width W11 of the power generation cell anode gas introduction flow path 120e at the lowest end in the gravity direction is larger than the flow path width W15 of the power generation cell anode gas introduction flow path 120a at the uppermost end in the gravity direction. In addition, in a case where power generation cell anode gas introduction flow paths 120a, 120b, 120c, 120d, and 120e include two or more flow path widths, the power generation cell anode gas introduction flow path 120a at the lowest end in the direction of gravity may have the largest flow path width of the power generation cell anode gas introduction flow paths 120a, 120b, 120c, 120d, and 120e.When liquid water enters the anode gas supply manifold 420 and reaches the power generation cell 100, the power generation cell anode gas introduction flow path 120a is blocked at the lowest end in the gravity direction first. Fig. In the example shown in Figure 12, the power generation cell anode gas introduction flow path 120a is not completely blocked by liquid water at the lowest end of the gravity direction.

[0032] According to the second embodiment, since the flow path width W11 of the power generation cell anode gas introduction flow path 120a at the lowest end in the gravity direction is larger than the average flow path width of the power generation cell anode gas introduction flow paths 120a to 120e, it becomes difficult for water to block the power generation cell anode gas introduction flow path 120a at the lowest end in the gravity direction. As a result, the pressure difference between the inlet and outlet of the power generation cell anode gas introduction flow path 120a is small, and it becomes difficult for liquid water to move to the center region 150 of the power generation cell 100.That is, according to the second embodiment, a configuration (second configuration) is proposed in which, in one or more power generation cells 100 adjacent to the dummy cell 200, the flow path width W6 of the power generation cell anode gas introduction flow path 120a at the lowest end in the gravity direction is larger than the average flow path width of the power generation cell anode gas introduction flow paths 120a, 120b, 120c, 120d, and 120e. Therefore, the movement amount V1 of the liquid water moving to the central region 150 of a specific power generation cell 100 is relatively reduced, so that the intensive intrusion of the liquid water into the central region 150 of the specific power generation cell 100 can be prevented. In addition, the amount of liquid water flowing through the anode gas supply manifold 420 decreases relatively downstream of the reaction gas.The one or more power generation cells 100 adjacent to the dummy cell 200 may therefore have the second configuration.

[0033] The fuel cell stack 10 may have a configuration of the first and second embodiments, or it may have both configurations. Third embodiment

[0034] Fig. 13 is a sectional view of the anode gas introduction flow path of the power generation cell 100 of a third embodiment, which is similar to the view in Fig. 4. In the first and second embodiments, the power generation cell anode gas introduction flow path 120 (120a to 120e) is formed by forming the anode gas introduction flow path forming portion 173 (see Fig. 4) of the anode separator plate 170. In contrast, in the third embodiment, grooves 161 connected to the anode gas supply manifold 420 are formed in the frame 160, and the power generation cell anode gas introduction flow paths 120 are formed using these grooves 161. The same applies to the anode gas discharge flow path, the cathode gas introduction flow path, and the cathode gas discharge flow path, and these flow paths are also formed in the dummy cell 200 by grooves 161 in the same manner.

[0035] Fig.14 is a plan view of the frame 160 of the power generation cell 100 of the third embodiment. The frame 160 has the comb-tooth-shaped grooves 161 on the membrane electrode assembly 154 side of the anode gas supply manifold 420. The comb-tooth-shaped grooves 161 are also formed for the anode gas discharge manifold 425, the cathode gas supply manifold 410, and the cathode gas discharge manifold 415. The comb-tooth-shaped grooves 161 are also formed for the manifolds 410, 415, 420, and 425 in the frame 160 of the dummy cell 200.In the third embodiment, the flow path widths of the power generation cell anode gas introduction flow paths 120a to 120e or the flow path widths of the dummy cell anode gas introduction flow paths 220a to 220e formed by the grooves 161 are determined to be equal to the flow path widths of the first embodiment or equal to the flow path widths of the second embodiment.

[0036] According to the third embodiment, the flow path widths of the power generation cell anode gas introduction flow paths 120a to 120e or the flow path widths of the dummy cell anode gas introduction flow paths 220a to 220e are the same as those of the first and second embodiments, so that the same effects as in the first and second embodiments can be achieved.

[0037] Furthermore, in the third embodiment, since the introduction flow paths or the discharge flow paths for the reactant gas are formed using the grooves 161 formed in the frame 160, separate anode separator plates 170 and cathode separator plates 180 need not be provided for the power generation cells 100 and the dummy cell 200, but common plates can be used. That is, it is not necessary to exchange a mold used for manufacturing the anode separator plate 170 and the cathode separator plate 180 for the power generation cell 100 and the dummy cell 200.

[0038] In the first to third embodiments, the anode gas introduction flow paths 120, 220 are shown as examples. However, the cathode gas introduction flow paths 110, 210 can be configured in the same way. modification

[0039] In each of the above-described embodiments, although the relationship in size between the flow path width W6 of the dummy cell anode gas introduction flow path 220a at the lowest end in the gravity direction and the flow path width W1 of the power generation cell anode gas introduction flow path 120a at the lowest end in the gravity direction has not been described, it is preferable that the flow path width W6 of the dummy cell anode gas introduction flow path 220a is narrower than the flow path width W1 of the power generation cell anode gas introduction flow path 120a. In this case, it becomes easier to clog the dummy cell anode gas introduction flow path 220a with liquid water. Thus, it becomes easier for the liquid water to move to the center region 250 of the dummy cell 200, and it becomes more difficult to block the power generation cell anode gas introduction flow path 120a with liquid water.As a result, the intensive penetration of liquid water into the central region 150 of the particular power generation cell 100 can be prevented.

Claims

[1] Fuel cell stack (10), comprising: a plurality of stacked power generation cells (100); and a dummy cell (200) which, of the two end portions of the power generation cells, is arranged at the end portion on an upstream side in a direction in which a reaction gas supplied to the fuel cell stack (10) flows, and which does not generate power, wherein: the fuel cell stack (10) has a reaction gas supply manifold (410, 420) passing through the power generation cells (100) and the dummy cell (200); the power generation cell (100) has a plurality of first introduction flow paths (110, 120a to 120e) arranged along a gravity direction for supplying the reaction gas from the reaction gas supply manifold (410, 420) to a power generation reaction; the dummy cell (200) has a plurality of second introduction flow paths (220a to 220e) arranged along the direction of gravity for supplying the reaction gas from the reaction gas supply manifold (410, 420) to a central region (250); and the fuel cell stack (10) has at least one of: a first configuration in which a flow path width (W6) of the second introduction flow path (220a) at a lowermost end of the second introduction flow paths in the direction of gravity is narrower than an average flow path width of the second introduction flow paths; and a second configuration in which a flow path width (W11) of the first introduction flow path (120a) at a lowermost end of the first introduction flow paths in the direction of gravity is larger than an average flow path width of the first introduction flow paths. [2] The fuel cell stack (10) of claim 1, wherein the fuel cell stack (10) has both the first configuration and the second configuration. [3] The fuel cell stack (10) according to claim 1 or 2, wherein the flow path width (W6) of the second introduction flow path (220a) at the lowest end in the gravity direction is narrower than the flow path width (W11) of the first introduction flow path (120a) at the lowest end in the gravity direction. [4] The fuel cell stack (10) according to any one of claims 1 to 3, wherein, in the first configuration, the flow path width (W6) of the second introduction flow path (220a) at the lowermost end of the second introduction flow paths is the narrowest width of the second introduction flow paths. [5] The fuel cell stack (10) according to claim 4, wherein, in the first configuration, with respect to the flow path widths of the second introduction flow paths, the flow path widths of the second introduction flow paths arranged above the second introduction flow path (220a) at the lowest end are determined such that the farther the second introduction flow path is from the second introduction flow path (220a) at the lowest end, the larger the flow path width of the second flow path becomes. [6] The fuel cell stack (10) according to any one of claims 1 to 5, wherein, in the second configuration, the flow path width (W11) of the first introduction flow path (120a) at the lowermost end of the first introduction flow paths is the largest width of the first introduction flow paths. [7] The fuel cell stack (10) according to claim 6, wherein, in the second configuration, the flow path widths of the first introduction flow paths arranged above the first introduction flow path (120a) at the lowest end are determined such that the farther the first introduction flow path is from the first introduction flow path (120a) at the lowest end, the narrower the flow path width of the first introduction flow path becomes.

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