JP2008108571A - Separator and fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent or suppress a decrease in flow velocity at the downstream of a fluid channel, and also to suppress or prevent a partial decrease in flow rate in the face direction of fluid. <P>SOLUTION: In an oxidizing gas channel 126 formed in a separator 122, a plurality of channel grooves 126a-126h have bent sections 140b, 140d in the surface of the separator 122, and a merging section where adjacent channels merge in the bent sections 140b, 140d. The number of merging channels differs between outer and inner peripheries of the bent sections 140b, 140d, and the channels may merge only at the inner periphery. Instead of the oxidizing gas channel 126, a fuel gas channel and a refrigerant channel may be used. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a separator having a fluid flow path and a fuel cell.

  An outline of the configuration of a conventional fuel cell will be described. As illustrated in FIG. 12, a cathode catalyst layer 14 (also referred to as a cathode electrode or an oxidizer electrode) is formed on one surface of the electrolyte membrane 12, and an anode catalyst layer 16 (also referred to as an anode electrode or a fuel electrode) on the other surface. And the anode diffusion layer 20 outside the cathode catalyst layer 16 and the anode diffusion layer 20 outside the anode catalyst layer 16, respectively, so-called membrane electrode assembly. (MEA) is configured. Further, a cathode side separator 22 in which an oxidizing gas channel 26 and a cell refrigerant channel 30 are formed is formed outside the cathode diffusion layer 18, and a fuel gas channel 28 and a cell refrigerant flow are formed outside the anode diffusion layer 20. The anode side separator 24 in which the path 30 is formed is integrated by, for example, adhesion or the like, so that the unit cell 10 is formed.

  A cathode raw material such as oxygen or air (hereinafter also referred to as a raw material gas or a reactive gas) is used for the cathode catalyst layer 14, and an anode raw material such as hydrogen (hereinafter also referred to as a raw material gas or a reactive gas) is used for the anode catalyst layer 16. Each is supplied to generate electricity. By laminating a plurality of unit cells 10, a fuel cell having a desired power generation performance is formed. Such a fuel cell is normally controlled to have a predetermined temperature range of, for example, about 60 ° C. to 100 ° C. during power generation, but generates heat associated with a chemical reaction during power generation. A coolant such as water is circulated to prevent overheating of the fuel cell.

  FIG. 13 is a schematic diagram showing an example of the flow path structure of the oxidizing gas flow path 26 formed on the one side of the cathode side separator 22 in the cathode side separator 22 shown in FIG. In FIG. 13, the cathode separator 22 is penetrated in the stacking direction of the unit cells 10, and the oxidizing gas supply manifold 32 and the oxidizing gas discharge manifold 34 that communicate the oxidizing gas as the cathode raw material between the cells, and these An oxidizing gas flow path 26 is provided which communicates with both of the manifolds and branches into each single cell 10 to flow the oxidizing gas.

  The oxidizing gas flow channel 26 has a plurality of flow channel grooves 26a to 26f formed at almost equal intervals over the entire surface of the cathode side separator 22 pressed against the MEA. For example, as shown in FIG. The occurrence of defects such as fatigue deterioration of the MEA due to the uneven distribution of the surface pressure generated between the MEA and the MEA when pressed against the MEA 22 is suppressed or prevented. In addition, as shown in FIG. 13, each of the plurality of flow channel grooves 26 a to 26 f forming the oxidizing gas flow channel 26 is provided with bent portions 40 a, 40 b, 40 c, and 40 d, and the entire surface of the cathode separator 22. In FIG. 12, the oxidizing gas is efficiently supplied to the cathode diffusion layer 18 shown in FIG.

  As shown in FIGS. 12 and 13, the oxidizing gas introduced into the unit cell 10 from the oxidizing gas supply manifold 32 is subjected to a battery reaction via the MEA in the oxidizing gas channel 26. Specifically, at least a part of the oxidizing gas flowing through the oxidizing gas channel 26 is sent into the cathode catalyst layer 14 via the cathode diffusion layer 18. During the operation of the fuel cell, oxygen in the oxidizing gas sent to the cathode catalyst layer 14 is consumed together with hydrogen ions that have passed through the electrolyte membrane 12 from the anode catalyst layer 16 side and electrons supplied through an external circuit. Generate.

  That is, as shown in FIG. 13, in the oxidizing gas flow path 26, the oxidizing gas flows into the oxidizing gas according to the oxidizing gas flow from the oxidizing gas supply manifold 32 side, that is, the upstream side, to the oxidizing gas discharge manifold 34 side, that is, the downstream side. The contained oxygen is gradually consumed by the battery reaction in the MEA. For this reason, the amount of oxidizing gas flowing in the downstream side of the oxidizing gas flow channel 26 is reduced by at least the amount of consumed oxygen gas compared to the amount of oxidizing gas flowing in the upstream side of the oxidizing gas flow channel 26. .

  Further, at least a part of the water generated in the cathode catalyst layer 14 flows into the oxidizing gas flow path 26 as a gas via the cathode diffusion layer 18. For this reason, the amount of water in the oxidizing gas flow path 26 generally gradually increases as it advances from the upstream side to the downstream side.

  As described above, the oxidizing gas discharged from the oxidizing gas discharge manifold 34 to the outside of the unit cell 10, that is, the used oxidizing gas, has an oxygen partial pressure as compared with the oxidizing gas introduced from the oxidizing gas supply manifold 32. While decreasing, the partial pressure of water is increasing.

  If moisture in the cathode catalyst layer 14 and / or the oxidizing gas channel 26 stays without being sufficiently discharged, when at least part of the moisture is condensed, the gas channel is blocked, so-called flooding, and oxidation occurs. There is a risk of a decrease in output due to insufficient gas supply. For this reason, the flow rate or flow rate of the oxidant gas flowing through the oxidant gas channel 26, particularly the oxidant gas flow rate, tends to decrease so as to reliably discharge the moisture in the oxidant gas channel 26 to the outside of the unit cell 10. In the downstream portion, it is desirable to maintain at least a predetermined flow velocity (lower flow velocity) or more.

  In order to maintain the flow rate of the oxidizing gas at least at a predetermined value or more in the downstream portion of the oxidizing gas flow channel 26, for example, a method of narrowing the groove depth or groove width of each flow channel of the oxidizing gas flow channel 26 in the downstream portion Can be considered. However, a significant change in the groove depth is not preferable because it is likely to cause uneven thickness of the separator and deteriorate the moldability. In addition, the change in the groove width is not preferable from the viewpoint of durability of the electrolyte membrane and the like because there is a possibility that the formability and the surface pressure load on the MEA may be uneven. On the other hand, according to the flow channel structures described in Patent Documents 1 to 6, it is considered that in any case, it is possible to suppress a decrease in the flow rate and / or flow rate of the fluid on the downstream side.

JP-A-11-250923 JP 2000-311696 A JP 2000-294261 A JP 2001-52723 A JP-A-2005-190714 JP 2004-55220 A

  However, in any case described in Patent Documents 1 to 6, the pressure loss is different between the outer portion and the inner portion of the bent portion, in which a plurality of flow channel grooves arranged in parallel are bent in the separator surface. As a result, a difference occurs in the flow rate and / or flow rate of the fluid in the separator surface, and the amount of reaction gas flowing per unit time (the amount of fuel gas that is a raw material for anode and / or the amount of oxidizing gas that is a raw material for cathode) There was a risk of variations.

  The variation in the amount of the reaction gas in the separator surface leads to the variation in the battery reaction depending on the MEA site. Therefore, depending on the MEA site, the predetermined power generation performance may not be sufficiently exhibited. Furthermore, the variation in the power generation property due to the MEA site may lead to local degradation of the MEA.

  Further, in the portion where the adjacent flow grooves are folded so that the gas traveling direction is reversed, the gas flows from the outer flow groove having a relatively high pressure loss to the inner flow groove through the diffusion layer. May flow in. In such a case, there is a problem that the gas flow rate in the outer channel groove is reduced and the drainage performance in the outer channel groove is lowered.

  An object of the present invention is to prevent or suppress a decrease in flow velocity in a downstream portion of a fluid flow path, and to reduce or prevent a partial flow rate variation in a fluid surface direction.

  In addition, another object of the present invention is to suppress or prevent a decrease in flow rate particularly in a bent portion in a fluid flow channel including a plurality of flow channel grooves having a bent portion in the surface direction of the separator.

  Furthermore, another object of the present invention is to suppress or prevent the occurrence of flooding in the reaction gas flow path.

  The configuration of the present invention is as follows.

  (1) The plurality of flow channel grooves have a bent portion in the separator surface, and the bent portion has a flow channel structure including a merge portion where adjacent flow channels merge with each other, and an outer peripheral portion of the bent portion. And the number of flow paths that merge at the inner periphery differs.

  (2) The separator according to (1), wherein the number of merged channels in the inner circumferential portion is greater than the number of merged channels in the outer circumferential portion.

  (3) The separator according to (2), wherein the merging portion is provided only at an inner peripheral portion of the bent portion.

  (4) The flow channel structure has a plurality of bent portions in the separator surface, and a plurality of flow channel grooves have a flow path while reducing the flow channel cross-sectional area from the upper upstream side to the lower downstream side, The region where the fluid flows in the separator plane when the separator is installed is longer in the vertical direction than in the horizontal direction.

  (5) The separator according to (4), wherein the fluid is a reactive gas.

  (6) The separator according to (4), wherein the fluid is an oxidizing gas.

  (7) The plurality of flow channel grooves have a bent portion in a plane parallel to the unit cell, and the bent portion has a flow channel structure including a merge portion where adjacent flow channels merge with each other, and the bent portion A fuel cell in which the number of flow paths that merge at the outer peripheral portion and the inner peripheral portion is different.

  (8) A flow channel structure in which a fluid is circulated from the upper upstream side to the lower downstream side while reducing the flow channel cross-sectional area, and the plurality of flow channel grooves have a plurality of bent portions in a plane parallel to the unit cell. The region in which the fluid flows in the plane is longer in the vertical direction than in the horizontal direction when the unit cell is installed.

  (9) The fuel cell according to (8), wherein the fluid is a reactive gas.

  According to the present invention, it is possible to prevent or suppress a decrease in the flow velocity in the downstream portion of the fluid flow path and to suppress or prevent a partial decrease in the flow rate in the surface direction of the fluid.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic view showing an example of a flow channel structure of an oxidizing gas flow channel 126 formed on one side of the cathode side separator 122 in the cathode side separator 122 in the embodiment of the present invention. In FIG. 1, the cathode side separator 122 has substantially the same configuration as the cathode side separator 22 except that it has an oxidizing gas passage 126 instead of the oxidizing gas passage 26 of the cathode side separator 22 shown in FIG. 11. ing.

  In FIG. 1, the oxidizing gas flow path 126 formed on one side of the cathode side separator 122 includes a plurality of flow path grooves formed at almost equal intervals over the entire surface of the cathode side separator 122 that is pressed against the MEA. Each of the channel grooves is provided with a plurality of bent portions so that the oxidizing gas can be efficiently supplied to the cathode diffusion layer 18 (FIG. 12) over the entire surface of the cathode separator 122. .

  In the oxidant gas channel 126, the number of channel grooves is reduced from eight to six by joining the channel grooves 126a to 126d flowing on the inner peripheral side at the bent portion 140b. Further, in the bent portion 140d, the number of the channel grooves is further reduced from six to four by joining the channel grooves 126e to 126h flowing on the inner peripheral side. As described above, the oxidizing gas passage 126 gradually decreases the number of the channel grooves, thereby reducing the oxidizing gas discharge manifold 34 without reducing the flow rate of the oxidizing gas introduced from the oxidizing gas supply manifold 32 to a predetermined value or less. It becomes possible to distribute it.

  FIG. 2 is an enlarged view showing a portion surrounded by C in the oxidizing gas channel 126 shown in FIG. Of the oxidizing gas flow path 126, the flow path groove 126a and the flow path groove 126b adjacent to the flow path groove 126b join at the bent portion 140b, and a flow path groove 126ab that joins is joined to the downstream side of the bent portion 140b. It is formed. Similarly, the channel groove 126c and the channel groove 126d adjacent to the channel groove 126c merge at the bent portion 140b, and accordingly, the channel groove 126cd is formed on the downstream side of the bent portion 140b. As described above, in the bent portion 140b, the number of grooves is reduced from eight to six on the downstream side of the bent portion 140b by joining the flow path grooves flowing through the inner peripheral portion. Note that the channel widths of the channel grooves 126ab and 126cd where adjacent channel grooves join each other are substantially the same as the channel widths of the channel grooves 126a to 126h.

  On the other hand, in the bent portion 140d shown in FIG. 1, the flow channel grooves 126g and 126h and the flow channel grooves 126e and 126f flowing through the inner portion are joined together, similarly to the bent portion 140b described above. For this reason, the number of grooves is reduced from six to four on the downstream side of the bent portion 140d. Further, the channel widths of the channel grooves 126gh and 126ef, which are joined by the adjacent channel grooves, are almost the same as the channel widths of the channel grooves 126a to 126h.

  That is, the oxidizing gas channel 126 includes a merging portion where the adjacent channels merge at the bent portions 140b and 140d, and gradually reduces the number of grooves while gradually decreasing from the upstream side to the downstream side. The area is reduced. At this time, by having the merging portion only at the inner peripheral portion of the bent portion, the flow velocity and / or flow rate of the fluid flowing through the outer peripheral portion of the bent portion, and the flow velocity and / or flow of the fluid flowing through the inner peripheral portion of the bent portion. It is possible to adjust the flow rate, and the flow rate of the oxidant gas flowing through the cathode separator 122 in the oxidant gas channel 126 does not change significantly over the entire surface, and is approximately the same.

  The merging of the channel grooves at the bent portion can be appropriately set depending on various conditions such as the shape of the fluid channel and the type of fluid to be circulated. That is, in another embodiment of the present invention, if the number of flow paths that merge at the outer peripheral portion and the inner peripheral portion of the bent portion is different, it is possible to merge at the outer peripheral portion, The number of merged channels is preferably greater than the number of merged channels in the outer periphery. If the number of merges is the same between the outer peripheral part and the inner peripheral part, the difference between the fluid flow rate flowing through the outer peripheral part and the fluid flow rate flowing through the inner peripheral part is not much different from that before the merge, or is further deteriorated.

  FIG. 3 schematically illustrates a cathode side separator in another embodiment of the present invention and a channel structure of an oxidizing gas channel formed on one side of the separator. As shown in FIG. 3, the flow paths adjacent to each other merge regardless of the shape of the cathode-side separator and the position where the oxidizing gas supply manifold 32 and / or the oxidizing gas discharge manifold 34 are arranged. Having a flow path structure including a merging portion, and making the flow of the oxidant gas suitable for the entire oxidant gas flow path by varying the number of flow paths that merge at the outer peripheral portion and the inner peripheral portion of the bent portion Is possible.

  For example, in FIG. 3 (a), each channel groove is formed, the groove width is defined, and the shape of the groove 31 that contacts the MEA is a shape having a predetermined width. The shape of the distal end portion 31a does not have to be rectangular as shown in FIGS. 3A to 3F, and may be appropriately formed so as to reduce the resistance of the circulating fluid. For example, it may be a tapered shape, or may be a rounded so-called R-cut shape, and may be appropriately set according to the characteristics of the fluid to be circulated.

  In both of the fluid flow paths shown in FIG. 1 and FIG. 3, two adjacent flow grooves are joined together. However, the present invention is not limited to this, and three or more flow grooves may be joined at once. Is possible.

  In all of the above-described embodiments, the oxidizing gas flow path formed on one side of the cathode separator is taken as an example, that is, the fluid flowing through the fluid flow path is described as the oxidizing gas. The present invention is not limited to this, and it is also effective in the case where fuel gas is circulated, which is required to maintain a uniform flow rate in the flow path surface, similarly to the oxidizing gas. Furthermore, as another embodiment, the present invention is also effective when applied to a refrigerant flow path for circulating a refrigerant, because the cooling performance can be improved by adjusting the pressure loss.

  As described above, in the fluid flow path including a plurality of flow path grooves having a bent portion in the separator surface and a merging portion in which the flow paths adjacent to each other merge in the bent portion, the outer peripheral portion and the inner periphery of the bent portion The flow rate in the separator surface can be reduced without decreasing the flow velocity from the upstream side to the downstream side of the fluid flow path by making the number of flow paths that merge at the section different, especially by joining the flow path grooves at the inner periphery. Can be made uniform.

  As another embodiment of the present invention, for example, one flow channel groove can be branched into two or more at a bent portion. When this configuration is applied, the flow velocity of the fluid flowing downstream is lowered, which is not preferable. However, for example, in order to obtain an optimum reaction gas flow rate and / or flow velocity distribution on the cell reaction surface, a certain limited portion is required. If the flow rate and / or flow rate of the gas only needs to be actively reduced, or if it is necessary to adjust the flow rate of the reaction gas or refrigerant flowing through each of the stacked single cells, It is also possible to apply a combination of merge and branch.

  FIG. 4 is a schematic diagram showing an example of the flow path structure of the oxidizing gas flow path 226 formed in the cathode side separator 222 according to another embodiment of the present invention, particularly on one surface side of the cathode side separator 222. In FIG. 4, the cathode side separator 222 has substantially the same configuration as the cathode side separator 122 except that the cathode side separator 222 has an oxidizing gas channel 226 instead of the oxidizing gas channel 126 of the cathode side separator 122 shown in FIG. 1. ing.

  The oxidant gas flow path 226 shown in FIG. 4 has more bent portions than the oxidant gas flow path 126 shown in FIG. 1 (5 places in FIG. 1 are 10 places in FIG. 4), and 4 of them are bent. In the parts (240c, 240e, 240g, and 240i), the number of the channel grooves is gradually reduced by joining the channel grooves flowing through the inner peripheral portion (8 → 6 → 4 → 3 → 2). The fluid is circulated from the upstream side to the downstream side (here, the oxidizing gas supply manifold 32 side to the oxidizing gas discharge manifold 34 side) while reducing the cross-sectional area of the flow path. In this way, by appropriately setting the number of bent portions, the number of flow channel grooves can be adjusted multiple times in stages, and the flow velocity and / or flow rate of the fluid can be controlled over the entire oxidizing gas flow channel 226. A more preferable state can be obtained.

  When the cathode separator 222 shown in FIG. 4 is combined with a unit cell and other members to form a fuel cell, the upstream side oxidizing gas supply manifold 32 side is preferably upward and the downstream side oxidizing gas discharge manifold 34 side is preferably downward. Arranged as. According to such a channel groove configuration, the flow rate gradually decreases as the length in the horizontal direction becomes longer. Therefore, under conditions where moisture is mixed in the reaction gas, the flow is caused by condensation of moisture. Flooding is likely to occur in the horizontal part of the road groove. By making the region in which the fluid flows in the separator surface when the separator is installed longer in the vertical direction or in the vertical direction than in the horizontal direction, that is, by setting X <Y in FIG. In particular, it is possible to prevent or suppress the occurrence of flooding particularly in the horizontal portion of the flow channel.

  In addition, the fluid flow path shown in the above-described embodiment is not limited to the oxidizing gas flow paths 126 and 226 as shown in FIGS. 1 and 4, but can be applied to a fuel gas flow path. . By applying this configuration to the fuel gas flow path, it is possible to contribute to suppression or prevention of flooding derived from moisture contained in the wet fuel gas.

  In the present embodiment, in the stationary fuel cell, the fuel cell is held in a mounted state. It is assumed that the horizontal, vertical, or vertical direction may deviate from the above-mentioned direction due to the inclination, but even when installed in such a moving body, for example, when it is placed in an inclined state during movement However, by always making the region where the fluid flows in the fluid flow path longer in the vertical direction or in the vertical direction than in the horizontal direction, it is always possible to prevent the occurrence of flooding when operating or stopping at any place. It becomes possible to suppress.

  Further, the fluid flow path shown in the present embodiment is not limited to a reaction gas flow path such as an oxidant gas flow path or a fuel gas flow path, and can also be applied to a refrigerant flow path. Although it is not necessary to consider the influence of flooding in the refrigerant flow path, if the number of flow path grooves provided in each path is gradually reduced as described above, the decrease in the flow velocity on the downstream side is suppressed or prevented. It is possible to contribute to reduction of auxiliary machine power and improvement of cooling performance.

  In each of the above-described embodiments, in the bent portion of the fluid flow channel, the number of flow channel grooves, that is, the configuration in which the cross-sectional area of the flow channel is reduced by merging the flow channel grooves flowing through the inner peripheral portion, Not limited to this. Contrary to the configuration as described above, in the bent part of the fluid flow path, the number of flow paths in the outer peripheral part is less than the inner peripheral part so that the cross-sectional area in the outer peripheral part is reduced from the inner peripheral part. It is good also as a structure more than the number of merge, and it is good also as a structure which has a merge part only in an outer peripheral part as other embodiment. According to such a configuration, compared with a configuration in which the number of merged channels in the inner circumferential portion is greater than the number of merged channels in the outer circumferential portion, the flow circulates between the channel grooves between the inner circumferential portion and the outer circumferential portion in the bent portion. Although the reduction in the difference between the gas flow rate and / or the flow velocity cannot be expected, by reducing the pressure loss of the fluid flow path that circulates on the inner peripheral side, and increasing the flow rate on the outer peripheral side where the fluid flow rate is small, for example, It becomes possible to contribute to the improvement of drainage in the reaction gas channel.

  As a configuration of the fluid flow path having a plurality of bent portions, a model as shown in FIG. 5 was assumed and examined. In FIG. 5, the first bent portion (1) -the first horizontal portion (2) -the second bent portion (3) are passed through the first path 50, the third bent portion (4) -the second. From the horizontal portion (5) to the fourth bent portion (6) to the second path 52, the fifth bent portion (7) to the third horizontal portion (8) to the sixth bent portion (9) The third path 54, the seventh bent portion (10), the fourth horizontal portion (11), and the eighth bent portion (12) are defined as the fourth path 54. Further, the first bent portion 60, the fourth bent portion (6), and the fifth bent portion (7) are combined by combining the second bent portion (3) and the third bent portion (4). The second folded portion 62, the sixth folded portion (9), and the seventh folded portion (10) may be collectively referred to as a third folded portion 64, respectively.

  In FIG. 5, the fluid flow path is composed of a plurality of parallel flow path grooves, and the groove widths and depths of the plurality of flow path grooves are substantially uniform over the entire fluid flow path. As shown in FIG. 5, let A and B be the flows along the opposing walls among the plurality of flow channel grooves in the upstream portion. The groove widths and groove depths of the plurality of flow channel grooves are substantially uniform over the entire fluid flow channel, and the flow channel cross-sectional areas of the flow channel grooves A and B are both the first bent portion (1) to the first bent portion (1). Up to 8 bends (12) is almost constant. In addition, as a fluid flow path shown below, the oxidation gas flow path formed on one surface side of the cathode side separator is described as an example unless otherwise specified. That is, in the present embodiment, the flow rate of the fluid flowing through the fluid flow path is not constant from the first path 50 to the fourth path 56, and oxygen in the oxidizing gas is gradually consumed by the operation of the fuel cell. As a result, the flow rate of the oxidizing gas gradually decreases.

<Embodiment 1>
[Example 1]
FIG. 6 shows how the average flow velocity of the fluid flowing through each path changes when the number of channel grooves provided in each path is gradually reduced in the fluid flow path as shown in FIG. Indicated. As shown in FIG. 6, by gradually decreasing the number of grooves, it is possible to adjust the flow velocity of the fluid so as not to fall below the limit value (lower limit flow velocity) of the flow velocity at which flooding occurs.

[Comparative Example 1]
FIG. 7 shows how the average flow velocity of the fluid flowing through each path changes when the number of the channel grooves is constant in the fluid channel as shown in FIG. As shown in FIG. 7, when the number of grooves is not reduced, the flow rate gradually decreases as it goes downstream, and flooding may occur if the flow rate becomes lower than the lower limit flow rate value. Although it is possible to prevent the flow velocity from becoming lower than the lower limit flow velocity value by increasing the flow velocity in advance, it is not preferable because auxiliary power is required.

<Embodiment 2>
In the fluid flow channel as shown in FIG. 5, when the number of flow channel grooves provided in each path is gradually reduced, the difference in flow rate depending on the position of the merging portion will be examined.

[Comparative Example 2]
FIG. 8 is a diagram showing a change in flow rate for each flow channel in each part shown in FIG. 5 when the number of flow channels is made constant from the upstream side to the downstream side. In FIG. 8 and FIGS. 9 to 11 described below, the change in the flow rate in the channel grooves A and B shown in FIG. 5 is shown. As shown in FIG. 8, in the flow channel groove A and the flow channel groove B, the flow rates in the horizontal portions (2), (5), (8) and (11) are almost the same, but in the bent portion. The difference in the flow rate of fluid flowing through the flow channel A and the flow channel B is large.

[Reference Example 1]
9 shows that the number of channel grooves in each of the folded portions shown in FIG. 5 is such that the adjacent channel grooves in the channel grooves arranged on the inner peripheral side and the outer peripheral side are uniformly joined. Thus, the case where the number of grooves is reduced is shown. As shown in FIG. 9, the difference in the flow rate of the fluid flowing through the flow channel groove A and the flow channel groove B is not much different from that in FIG.

[Reference Example 2]
FIG. 10 shows the number of channel grooves in each of the folded portions shown in FIG. 5 by joining adjacent channel grooves in the channel grooves arranged on the outer peripheral side, and joining the inner peripheral side. This is a case where the number of grooves is gradually reduced without making it. As shown in FIG. 10, a larger flow rate difference is generated compared to the configuration shown in FIG.

[Example 2]
FIG. 11 shows the number of channel grooves in each of the folded portions shown in FIG. 5. The adjacent channel grooves in the channel grooves arranged on the inner peripheral side are merged, and the outer circumferential side is merged. This is a case where the number of grooves is gradually reduced without making it. According to this configuration, the flow rate of the fluid can be made substantially uniform over the entire surface with almost no difference in the flow rate over the entire fluid flow path.

  As shown in FIG. 8, according to the configuration in which the merging portion is not provided in the folded portion, the flow of the fluid tends to stay on the outer peripheral portion side where the distance becomes long. However, as in the present configuration, the merging portion joins the inner peripheral portion. The inner circumference side and the outer circumference by reducing the number of flow channel grooves on the inner circumference side and making the inner circumference side high pressure loss and relatively increasing the flow rate of fluid flowing through the outer circumference side. The difference in the flow rate of fluid flowing through the side is reduced, or the fluid flow rate becomes substantially uniform.

  In addition, the junction part provided in each folding | turning part may be provided in the 2nd bending part (3) side in the 1st folding | turning part 60 shown, for example in FIG. 5, and is provided in the 3rd bending part (4) side. May be. Similarly, in any other folded portion, the merging portion may be provided at any one of the bent portions, but it is preferable that the flow rate difference be suppressed as much as possible over the entire fluid flow path.

  As described above, in the fluid flow path including a plurality of flow path grooves having a bent portion in the separator surface and a merging portion in which the flow paths adjacent to each other merge in the bent portion, the outer peripheral portion and the inner periphery of the bent portion The flow rate in the separator surface can be reduced without decreasing the flow velocity from the upstream side to the downstream side of the fluid flow path by making the number of flow paths that merge at the section different, especially by joining the flow path grooves at the inner periphery. Can be made uniform.

  In general, the present invention is not limited to a separator capable of forming a fluid flow path, and can be applied to any fluid flow path shape in a fuel cell, such as a fluid flow path formed in a resin frame when a metal separator is used. Is possible.

It is the schematic which shows an example of the flow-path structure of the fluid in embodiment of this invention. FIG. 2 is an enlarged view showing a portion surrounded by C in the oxidizing gas channel 126 shown in FIG. 1. It is the schematic which illustrates the flow-path structure of the fluid in embodiment of this invention. It is the schematic which shows an example of the flow-path structure of the fluid in other embodiment of this invention. It is a schematic diagram which shows the outline of a structure of the fluid flow path which has a some bending part. It is a figure which illustrates the mode of the change of the average flow velocity of the fluid which distribute | circulates each path | pass when the number of the flow-path grooves provided in each path | pass is decreased gradually. It is a figure which illustrates the mode of the change of the average flow velocity of the fluid which distribute | circulates each path | pass when the number of flow-path grooves is made constant. FIG. 6 is a diagram showing a change in flow rate for each channel groove in each part shown in FIG. 5 when the number of channel grooves is constant. FIG. 6 is a diagram showing a case where the number of channel grooves is uniformly merged between the inner peripheral side and the outer peripheral side in each of the folded portions shown in FIG. 5. FIG. 6 is a diagram showing the number of flow channel grooves in each of the folded portions shown in FIG. 5 when only the outer peripheral side is merged. FIG. 6 is a diagram illustrating the number of flow channel grooves in each of the folded portions illustrated in FIG. 5 when only the inner peripheral side is merged. It is the schematic which shows an example of the flow path structure of the conventional fluid. It is a schematic diagram which shows the outline of a structure of a fuel cell unit cell.

Explanation of symbols

  10 unit cell, 12 electrolyte membrane, 14 cathode catalyst layer, 16 anode catalyst layer, 18 cathode diffusion layer, 20 anode diffusion layer, 22, 122, 222 cathode side separator, 24 anode side separator, 26, 126, 226 Oxidizing gas flow 28, fuel gas flow path, 30 cell refrigerant flow path, 31 groove mountain, 31a tip, 32 oxidant gas supply manifold, 34 oxidant gas discharge manifold, 50 first pass, 52 second pass, 54 third Pass, 56 fourth pass, 60 first fold, 62 second fold, 64 third fold.

Claims (9)

A plurality of flow channel grooves have a bent portion in the separator surface, and the bent portion has a flow channel structure including a merge portion where adjacent flow channels merge with each other,
The separator characterized by the number of the flow paths which merge in the outer peripheral part and inner peripheral part of the said bending part differing. The separator according to claim 1,
A separator characterized in that the number of merged channels in the inner peripheral portion is larger than the number of merged channels in the outer circumferential portion. The separator according to claim 2,
The said junction part has only in the inner peripheral part of the said bending part, The separator characterized by the above-mentioned. While flowing the fluid while reducing the cross-sectional area of the flow path from the upper upstream side to the lower downstream side, the flow path structure has a plurality of bent portions in the separator plane,
The separator is characterized in that the region where the fluid flows in the separator surface when the separator is installed is longer in the vertical direction than in the horizontal direction. The separator according to claim 4,
A separator, wherein the fluid is a reactive gas. The separator according to claim 4,
The separator is characterized in that the fluid is an oxidizing gas. A plurality of flow channel grooves have a flow channel structure including a bent portion in a plane parallel to the unit cell, and the bent portion includes a merge portion where flow channels adjacent to each other merge.
2. The fuel cell according to claim 1, wherein the number of flow paths that merge at the outer peripheral portion and the inner peripheral portion of the bent portion is different. It has a flow channel structure in which a fluid flows from the upper upstream side to the lower downstream side while reducing the flow channel cross-sectional area, and the plurality of flow channel grooves have a plurality of bent portions in a plane parallel to the unit cell. ,
The region where the fluid flows in the plane is longer in the vertical direction than in the horizontal direction when the unit cell is installed. The fuel cell according to claim 8, wherein
The fuel cell, wherein the fluid is a reactive gas.

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