JP2016207264A - Fuel battery and fuel battery system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel battery system capable of achieving high reliability.SOLUTION: A fuel cell includes a flat plate type cell configured by sandwiching electrolyte between a fuel electrode and an air electrode, a flat plate type first separator arranged on the fuel electrode side, and a flat plate arranged on the air electrode side. The first separator includes an inlet manifold to which fuel gas is supplied, an outlet manifold through which the fuel gas is discharged, a first flow path portion which is formed on a main surface on a side in contact with the fuel electrode and intercommunicates with the inlet manifold on one end side thereof and through which the fuel gas supplied from the inlet manifold flows, a gas merging portion for joining the fuel gas flowing through the first flow path portion, and a second flow path portion which is formed on the main surface, arranged in parallel to the first flow path portion and communicates with the outlet manifold at an end portion thereof on the same side as the one end portion of the first flow path portion through which the fuel gas joined at the gas merging portion flows to the outlet manifold. The flow path cross-sectional area of the second flow path portion is smaller than the flow path cross-sectional area of the first flow path portion.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fuel cell and a fuel cell system.

Oxide ion conductors typified by stabilized zirconia are widely used as electrolyte materials for solid oxide fuel cells. As an electrolyte material, it has also been proposed to use a proton conductor represented by, for example, BaZrCeMO _3-α (M is a metal) (see Patent Document 1).

JP 2001-307546 A JP2007-207744

  An object of the present invention is to provide a fuel cell capable of obtaining high reliability as an example.

  An aspect of the fuel cell according to the present invention includes a flat plate cell configured by sandwiching an electrolyte between a fuel electrode and an air electrode, and a flat plate-shaped cell disposed on the fuel electrode side that sandwiches the cell. A first separator and a flat plate-like second separator disposed on the air electrode side, the first separator including an inlet manifold to which fuel gas is supplied, an outlet manifold from which the fuel gas is discharged, and A first flow passage portion formed on a main surface in contact with the fuel electrode, communicated with the inlet manifold at one end portion thereof, and circulates the fuel gas supplied from the inlet manifold; and the first flow passage portion A gas merging portion for merging the fuel gas flowing through the main surface and an end on the same side as an end on one side of the first flow passage portion, arranged in parallel with the first flow passage portion At the exit Manihoe And a second flow path section for flowing the fuel gas merged at the gas merge section toward the outlet manifold, and the flow path cross-sectional area of the second flow path section is: It becomes smaller than the channel cross-sectional area of the first channel part.

  According to the fuel cell of one embodiment of the present invention, there is an effect that high reliability can be obtained.

FIG. 1 is a perspective view showing a schematic configuration of a fuel cell according to an embodiment of the present invention. FIG. 2 is a plan view showing a schematic configuration of a first separator provided in the fuel cell shown in FIG. FIG. 3 is a plan view showing a schematic configuration of the first separator provided in the fuel cell according to Modification 1 of the embodiment of the present invention. FIG. 4 is a plan view showing a schematic configuration of the first separator provided in the fuel cell according to Modification 2 of the embodiment of the present invention. FIG. 5 is a plan view showing an example of a schematic configuration in which a plurality of first separators provided in a fuel cell according to Modification 1 of the embodiment of the present invention are arranged on one surface. FIG. 6 is a perspective view schematically showing an example of a fuel cell system including the fuel cell 100 according to Modification 1 or Modification 2 of the embodiment of the present invention.

(Background to obtaining one embodiment of the present invention)
The inventors of the present invention have made extensive studies on fuel cell. As a result, the following knowledge was obtained.

  For example, oxide ion conductors such as stabilized zirconia, which are widely used as electrolyte materials for solid oxide fuel cells, have a lower ionic conductivity as the temperature decreases. For this reason, a solid oxide fuel cell using an oxide ion conductor as an electrolyte material requires an operating temperature of 700 ° C. or higher.

  By the way, the higher the operating temperature, the more expensive special heat-resistant metal is required for the metal material used for the structural member. In addition, when the solid oxide fuel cell is started and stopped, the difference in thermal expansion increases, so that cracks are likely to occur. For this reason, there existed a subject that the cost of the whole fuel cell system containing a solid oxide form fuel cell became high, or reliability fell. Therefore, lowering the operating temperature of solid oxide fuel cells is one of the major goals in the practical application of fuel cell systems including solid oxide fuel cells.

In order to lower the operating temperature of the solid oxide fuel cell, either the thinning of the electrolyte or the change of the electrolyte material itself can be considered. For example, Patent Document 1 described above proposes to lower the operating temperature by using a proton conductor typified by, for example, BaZrCeMO _3-α (M is a metal) as the electrolyte material.

  By the way, when a proton conductor is used as an electrolyte in a solid oxide fuel cell, hydrogen in the fuel gas supplied to the fuel electrode side conducts in the proton conductor and reacts with oxygen on the air electrode side, Produce water. For this reason, as the electrochemical reaction between the fuel electrode and the air electrode proceeds, the volume of the supplied fuel gas decreases. In particular, the higher the fuel utilization rate is to improve the power generation efficiency, the greater the difference in volume of fuel gas between the downstream side of the fuel gas passage, which is the fuel gas passage in the solid oxide fuel cell, and the upstream side. growing. In other words, the flow rate of the fuel gas flowing through the downstream fuel gas flow channel is smaller than the flow rate of the fuel gas flowing through the upstream fuel gas flow channel.

  Here, when the flow rate of the fuel gas is “Q”, the cross-sectional area of the fuel gas flow channel is “A”, and the flow velocity of the fuel gas is “V”, the following equation (1) holds. . That is, the flow rate of the fuel gas is proportional to the flow rate of the fuel gas.

[Formula 1] Q = A · V (1)
For this reason, when the flow rate of the fuel gas flowing through the fuel gas flow path decreases, the flow rate of the fuel gas also decreases. That is, the flow rate of the fuel gas is lower on the downstream side than on the upstream side in the fuel gas flow path. When the flow rate of the fuel gas is reduced in this way, the supply amount of the fuel gas supplied to the fuel electrode per unit time is reduced, so that the power generation efficiency varies between the upstream side and the downstream side of the fuel gas flow path. As a result, variation in current distribution in the reaction surface of the cell increases.

  Here, in the reaction surface of the cell, the temperature is higher due to the heat generated by the power generation than the part where the power generation efficiency is higher than the part where the power generation efficiency is lower. Therefore, variation in power generation efficiency within the reaction surface of the cell means variation in temperature distribution within the reaction surface of the cell.

  Therefore, in order to reduce the variation in the temperature distribution in the reaction surface of the cell, it is necessary to make the flow velocity of the fuel gas flowing through the fuel gas flow path uniform. For example, Patent Document 2 proposes a polymer electrolyte fuel cell separator in which a fuel gas channel (flow region) devised to improve the uniformity of the flow rate of fuel gas is formed. In the separator disclosed in Patent Document 2, in the flow region of the fuel gas (reactive gas) formed in a serpentine shape, the number of channel grooves in the flow region located on the upstream side is positioned on the downstream side. The uniformity of the flow velocity of the fuel gas (reactive gas) is achieved by increasing the number of flow channels in the flow area.

  However, as in the separator disclosed in Patent Document 2, the present inventors can sufficiently reduce the variation in temperature distribution in the reaction surface of the cell only by improving the uniformity of the fuel gas flow velocity. I found it impossible.

  In particular, in solid oxide fuel cells, if the temperature distribution varies within the reaction surface of the cell, internal stress due to thermal expansion occurs in the cell, causing cracks or cracks. It becomes a big problem.

  Therefore, the present inventors diligently studied a fuel cell that can improve the uniformity of the flow velocity of the fuel gas flowing through the cell and reduce the variation in temperature distribution in the reaction surface of the cell. As a result, the following knowledge was reached.

  That is, the present inventors have improved the uniformity of the fuel gas flow velocity and the physical distance between the fuel gas inlet and outlet in the fuel cell separator (interconnector) in which the fuel gas flow path is formed. It has been found that the variation in temperature distribution in the reaction surface of the cell can be reduced by making both of the two approaches close to each other, and the present invention has been achieved. The present invention specifically provides the following modes.

  A fuel cell according to a first aspect of the present invention includes a flat plate cell configured by sandwiching an electrolyte between a fuel electrode and an air electrode, and a flat plate type first electrode disposed on the fuel electrode side that sandwiches the cell. A first separator and a flat plate-like second separator disposed on the air electrode side, the first separator including an inlet manifold to which fuel gas is supplied, an outlet manifold from which the fuel gas is discharged, and A first flow passage portion formed on a main surface in contact with the fuel electrode, communicated with the inlet manifold at one end portion thereof, and circulates the fuel gas supplied from the inlet manifold; and the first flow passage portion A gas merging portion for merging the fuel gas flowing through the main surface and an end on the same side as an end on one side of the first flow passage portion, arranged in parallel with the first flow passage portion Connected to the outlet manifold. And a second flow path section for flowing the fuel gas merged at the gas merge section toward the outlet manifold, and the flow path cross-sectional area of the second flow path section is the first flow path It becomes smaller than the flow path cross-sectional area of the path portion.

  According to the said structure, the 1st flow-path part, the gas confluence | merging part, and the 2nd flow-path part are formed in the main surface of the side which contacts the fuel electrode of a cell of the flat plate-shaped 1st separator. For this reason, it is possible to generate power in the cell using the fuel gas flowing through the first flow path part, the gas confluence part, and the second flow path part.

  In the first separator, the flow passage cross-sectional area of the second flow passage portion is smaller than the flow passage cross-sectional area of the first flow passage portion. The flow velocity can be increased by flowing into the second flow path portion from the merge portion. For this reason, the 1st separator can improve the uniformity of the flow velocity of the fuel gas which circulates over the 1st channel part and the 2nd channel part. Therefore, the fuel cell including the first separator can reduce the temperature difference between the temperature of the cell near the inlet manifold and the temperature of the cell near the outlet manifold.

  Further, the first flow path part and the second flow path part are arranged in parallel, and an inlet manifold and an outlet manifold are respectively provided at the end portions on the same side. Here, in the cell, a region near the inlet manifold where the flow rate of the fuel gas is large generates the largest amount of heat generated by power generation. Conversely, in the region near the outlet manifold where the flow rate of the fuel gas is the smallest, the amount of heat generated by power generation is the smallest. For this reason, the area | region with the largest calorific value and the smallest area | region in a cell are arrange | positioned at the edge part of the same side of each 1st flow volume part and 2nd flow volume part arrange | positioned in parallel. In the first flow path portion, the amount of heat generated by the cells gradually decreases from the inlet manifold toward the gas merge section, but the second flow path section flows in the opposite direction to the first flow path section, and the gas merge section The amount of heat generated by the cells gradually decreases from the outlet toward the outlet manifold. For this reason, variation in temperature distribution in the cell can be reduced, thereby preventing the cell from being cracked or cracked.

  Therefore, the fuel cell according to the first aspect of the present invention has an effect that high reliability can be obtained.

  The fuel cell according to a second aspect of the present invention is the fuel cell according to the first aspect described above, wherein the first flow path portion and the second flow path portion are a plurality of fuels having equal flow path cross-sectional areas and linear shapes. The first gas flow path portion may be configured such that the number of the fuel gas flow channels is larger than that of the second flow path portion.

  According to the said structure, in the 1st separator, the 1st flow path part and the 2nd flow path part are comprised from the several fuel gas flow path used as the same linear shape and the same flow-path cross-sectional area. This facilitates the design and production of the first separator.

  In the fuel cell according to the third aspect of the present invention, in the first or second aspect described above, the electrolyte may be a proton conductor made of a solid oxide.

  The fuel cell according to a fourth aspect of the present invention is the fuel cell according to any one of the first to second aspects described above, wherein the cell and the first separator are rectangular, A plurality of the inlet manifolds and the outlet manifolds may be provided on one side of the main surface, and the gas junction may be provided on a side opposite to the one side.

  Here, the rectangle means not only a quadrilateral whose angle is 90 degrees, but also a shape formed by dropping a corner or a shape where a corner portion is cut, and is mainly formed from four sides. .

  The fuel cell according to a fifth aspect of the present invention is the fuel cell according to the fourth aspect described above, wherein the inlet manifold is provided on each side of the main surface of the first separator on each side of the main surface. The outlet manifold may be provided in a central portion between the inlet manifolds provided on both end sides of the one side, and sandwiched by the inlet manifolds.

  According to the above configuration, the area near the inlet manifold where the calorific value of the cell is large can be arranged on both ends of one side, and the area near the outlet manifold where the calorific value is small can be arranged at the center. it can. For this reason, the dispersion | variation in the temperature distribution in a cell can be suppressed.

  A fuel cell system according to a sixth aspect of the present invention is a cell stack formed by laminating the cell, the first separator, and the second separator provided in the fuel cell according to the fourth or fifth aspect. And a plurality of branch pipes for equally distributing the supplied fuel gas to each of the plurality of inlet manifolds. Have

  According to the above configuration, the fuel gas can be distributed with a simpler structure than the structure in which the fuel gas is branched so as to be equally distributed inside the cell stack.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description, the same or corresponding components are denoted by the same reference symbols throughout the drawings, and the description thereof may be omitted.

[Embodiment]
(Configuration of fuel cell)
A configuration of a fuel cell 100 according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a perspective view showing a schematic configuration of a fuel cell 100 according to an embodiment of the present invention. In addition, a proton conduction type solid oxide fuel cell is illustrated as a fuel cell which concerns on embodiment.

As shown in FIG. 1, the fuel cell 100 includes a cell 1 and a separator 2 (a first separator 2a and a second separator 2b). The cell 1 is a rectangular flat plate cell in which an electrolyte 10 is sandwiched between a fuel electrode 11 and an air electrode 12. Examples of the material of the electrolyte 10 include an oxide material exhibiting proton conductivity. Examples of the oxide material include oxides made of barium, zirconium, cerium, and the like (for example, barium zirconate doped with a trivalent metal element (BaZrO ₃ )). The cell 1 is sandwiched between the first separator 2a and the second separator 2b. For convenience of explanation, the separator 2 is distinguished from the first separator 2a and the second separator 2b. However, the separator 2 is simply referred to as the separator 2 when it is not necessary to distinguish between them.

  The separator 2 electrically connects the fuel electrode 11 and the air electrode 12 and prevents the fuel gas and air from being mixed. The first separator 2a is disposed on the fuel electrode 11 side of the cell 1, the second separator 2b is disposed on the air electrode 12 side of the cell 1, and the first separator 2a and the second separator 2b are rectangular flat plate shapes. I am doing. Examples of main materials constituting the separator 2 include alumina, zirconia, magnesia, and strontium titanate. Note that when an electrically insulated material such as alumina, zirconia, or magnesia is used as a material constituting the separator 2, a conductor that connects the cell 1 and another cell and collects the generated power is required. . Therefore, for example, a hole may be formed in the separator 2 and a conductor made of a material such as a metal having high electrical conductivity may be filled in the hole.

  In addition, a fuel gas flow path 3 through which fuel gas flows is formed on the main surface of the first separator 2a on the side in contact with the fuel electrode 11, and the main surface on the side in contact with the air electrode 12 of the second separator 2b. An air flow path 4 through which air flows is formed on the surface.

  Although not particularly shown in FIG. 1, the main surface of the first separator 2 a opposite to the main surface on which the fuel gas channel 3 is formed is extended in a direction intersecting the fuel gas channel 3. On the other hand, on the main surface opposite to the main surface on which the air flow path 4 of the second separator 2b is formed, the fuel gas flow path extending in a direction intersecting the air flow path 4 3 is formed. In the fuel cell 100, the cells 1 and the separators 2 can be alternately stacked and electrically connected in series to form a cell stack 40 (see FIG. 6 described later). Although not particularly shown in FIG. 1, the fuel cell 100 according to the present embodiment includes an inlet manifold 21 (described later) in which fuel gas or air is supplied to, for example, the periphery of the cell 1 and the separator 2. 2), and a so-called internal manifold type fuel cell provided with an outlet manifold 22 (see FIG. 2 described later) from which fuel gas or air is discharged.

  The fuel cell 100 according to the present embodiment is characterized by the structure of the first separator 2a. In particular, the arrangement structure of the fuel gas passage 3 on the main surface of the first separator 2a on the side in contact with the fuel electrode 11 is characteristic. Therefore, the structure of the first separator 2a will be described below with reference to FIG. The arrangement structure of the air flow path 4 formed on the main surface of the second separator 2b on the side in contact with the air electrode 12 is the same as that of a conventionally known separator, and thus the description thereof is omitted.

(Structure of the first separator)
FIG. 2 is a plan view showing a schematic configuration of the first separator 2a included in the fuel cell 100 shown in FIG. 2, the main surface of the first separator 2a on the side in contact with the fuel electrode 11 is illustrated. Note that the left-right direction in FIG. 2 is referred to as a horizontal direction, and the up-down direction is referred to as a vertical direction.

  As illustrated in FIG. 2, the first separator 2 a includes an inlet manifold 21, an outlet manifold 22, a first flow path portion 23 a, a gas merging portion 24, and a second flow path portion 23 b.

  The inlet manifold 21 is a through hole through which fuel gas is supplied, and the outlet manifold 22 is a through hole through which fuel is discharged. The first separator 2a according to the present embodiment is rectangular and has a flat plate shape, and an inlet manifold 21 and an outlet manifold 22 are provided on one side of the main surface of the first separator 2a that is in contact with the fuel electrode 11. ing. That is, the inlet manifold 21 and the outlet manifold 22 are provided in the vertical direction on the left side of the first separator 2a in FIG.

  As shown in FIG. 2, the first flow passage portion 23a is a flow passage portion formed on the main surface of the first separator 2a on the side in contact with the fuel electrode 11, and communicates with the inlet manifold 21 at one end portion. Then, the fuel gas supplied from the inlet manifold 21 is circulated. The first flow path portion 23 a communicates with the gas merging portion 24 at the other end, and guides the fuel gas to the gas merging portion 24. The first flow path portion 23a of the first separator 2a according to the embodiment is composed of ten fuel gas flow paths 3 each having a substantially equal cross-sectional area and substantially linear shape. A first flow path portion 23 a composed of ten fuel gas flow paths 3 extends in the lateral direction from the inlet manifold 21 to the gas junction 24.

  The gas joining part 24 is a through hole that joins the fuel gas flowing through the first flow path part 23a. The gas merging portion 24 is located on the main surface of the first separator 2a on the side in contact with the fuel electrode 11 and on the side facing the one side where the inlet manifold 21 and the outlet manifold 22 are provided (the right side of the first separator 2a in FIG. 2). ). The fuel gas that has flowed through each fuel gas flow path 3 of the first flow path portion 23a is merged in the gas merging section 24 and is guided to the second flow path section 23b.

  As shown in FIG. 2, the second flow path portion 23b is a flow path portion formed on the main surface of the first separator 2a on the side in contact with the fuel electrode 11, and is arranged in parallel with the first flow path portion 23a. ing. The second flow path portion 23b communicates with the outlet manifold 22 at the end portion on the same side as the one end portion of the first flow path portion 23a. Further, the second flow path portion 23 b communicates with the gas merging portion 24 at an end portion opposite to an end portion on the side communicating with the outlet manifold 22. The second flow path portion 23 b causes the fuel gas merged at the gas merge portion 24 to flow toward the outlet manifold 22. More specifically, the second flow path portion 23b is composed of five fuel gas flow paths 3 each having a substantially equal cross-sectional area and substantially linear shape. A second flow path portion 23 b constituted by five fuel gas flow paths 3 extends laterally from the gas junction 24 to the outlet manifold 22. In addition, the fuel gas flow path 3 constituting the first flow path portion 23a and the fuel gas flow path 3 constituting the second flow path portion 23b are substantially equal to each other in cross-sectional area.

  In the first separator 2 a having the above-described configuration, the fuel gas supplied from the inlet manifold 21 flows through the fuel gas passage 3 of the first passage portion 23 a and reaches the gas junction portion 24. And the fuel gas which distribute | circulated the fuel gas flow path 3 of the 1st flow path part 23a merges in the gas confluence | merging part 24, and distribute | circulates the fuel gas flow path 3 of the 2nd flow path part 23b in the direction turned back from the gas confluence | merging part 24 To do. Then, the fuel gas that has flowed through the fuel gas flow path 3 of the second flow path portion 23 b is discharged from the outlet manifold 22. Thus, the flow direction of the fuel gas flowing through the first flow path portion 23a and the flow direction of the fuel gas flowing through the second flow path portion 23b are so-called counterflows that are opposite to each other.

  As described above, the first flow path portion 23 a is composed of ten fuel gas flow paths 3, and the second flow path portion 23 b is composed of five fuel gas flow paths 3. For this reason, the cross-sectional area of the second flow path portion 23b that can be obtained by adding the cross-sectional areas of the five fuel gas flow paths 3 is the cross-sectional area of the ten fuel gas flow paths 3. Is half of the channel cross-sectional area of the first channel part 23a that can be obtained by adding together. That is, in the first separator 2 a, the flow passage cross-sectional area of the second flow passage portion 23 b near the outlet manifold 22 is halved with respect to the flow passage cross-sectional area of the first flow passage portion 23 a near the inlet manifold 21.

  Incidentally, in the vicinity of the inlet manifold 21, the hydrogen concentration in the fuel gas flowing through the fuel gas flow path 3 is high. For this reason, the hydrogen gas consumed by the power generation in the cell 1 is supplied without delay. Therefore, in the region where the hydrogen concentration in the fuel gas is high, the power generation amount in the cell 1 is large, and the heat generation amount is accordingly increased. On the other hand, when the hydrogen concentration in the fuel gas decreases, the amount of power generation decreases, and the heat generation amount decreases accordingly. Therefore, in the first flow path portion 23a, the temperature of the cell 1 increases in the vicinity of the inlet manifold 21, but the hydrogen concentration in the fuel gas gradually decreases as the fuel gas moves toward the gas merging portion 24. And the calorific value both decreases. Further, when hydrogen is consumed in power generation, the volume of the fuel gas is reduced, and the flow rate of the fuel gas is also reduced.

  The fuel gas that has flowed from the inlet manifold 21 through the first flow path portion 23a merges at the gas merge section 24, and is then guided to the second flow path portion 23b. As shown in FIG. 2, the second flow path portion 23b has fewer fuel gas flow paths 3 than the first flow path portion 23a. For this reason, the flow path cross-sectional area of the second flow path portion 23 b indicated by the total of the five fuel gas flow paths 3 is the flow path of the first flow path portion 23 a indicated by the total of the ten fuel gas flow paths 3. It becomes smaller than the cross-sectional area. Therefore, the fuel gas guided from the gas merging portion 24 to the second flow path portion 23b can increase the flow velocity again.

  Thus, in the 1st separator 2a which concerns on this Embodiment, the fuel gas which flowed in into the gas confluence | merging part 24 with the flow velocity reduced rather than the flow velocity at the time of supply to the inlet manifold 21 is rather than the 1st flow path part 23a. The flow velocity can be increased again by flowing through the second flow path portion 23b having a small flow path cross-sectional area. For this reason, the uniformity of the flow velocity of the fuel gas can be enhanced over the entire first flow path portion 23a and the second flow path portion 23b. Therefore, as compared with the conventional separator in which the hydrogen in the fuel gas is consumed by power generation and the flow rate of the fuel gas gradually decreases, the fuel that passes per unit area in the fuel gas flow path 3 and per unit time. The gas flow rate can be increased. Therefore, it is possible to suppress the power generation amount of the cell 1 and a decrease in the heat generation amount of the heat generated due to the power generation also on the downstream side of the second flow path portion 23b.

  Further, the inlet manifold 21 and the outlet manifold 22 are configured to be located on the same side of the main surface on the fuel electrode 11 side of the first separator 2a. That is, the inlet separator 21 in the vicinity of the position where the power generation amount and the heat generation amount are the largest in the cell 1 and the outlet manifold 22 in the vicinity of the position where the power generation amount and the heat generation amount are the smallest in the cell 1 are the first separator. It is provided adjacent to the same side of the main surface of 2a. Further, the amount of heat generated in the reaction surface of the cell 1 is gradually reduced from the inlet manifold 21 toward the gas junction 24 (from the left to the right in FIG. 2). Further, the amount of heat generated in the reaction surface of the cell 1 has a relationship of further gradually decreasing from the gas junction 24 toward the outlet manifold 22 (from the right to the left in FIG. 2). Thus, since the position where the calorific value is high and the position where the calorific value is low can be adjacent to each other in the reaction surface of the cell 1, variations in the temperature distribution of the cell 1 can be suppressed.

  Therefore, in fuel cell 100 according to the present embodiment, variation in temperature distribution in the reaction surface of cell 1 can be reduced, and cracking or cracking in cell 1 can be prevented. Therefore, the fuel cell 100 can obtain high reliability.

  In the first separator 2a according to the present embodiment, the first flow path portion 23a is composed of ten fuel gas flow paths 3, and the second flow path portion 23b is composed of five fuel gas flow paths. However, the number of the fuel gas flow paths 3 included in each of the first flow path portion 23a and the second flow path portion 23b is not limited to this. Moreover, although the flow-path cross-sectional area of the fuel gas flow path 3 which each of the 1st flow-path part 23a and the 2nd flow-path part 23b has was substantially equal, it is not limited to this. For example, in the first separator 2a, both the first flow path portion 23a and the second flow path portion 23b include the same number of fuel gas flow paths 3, but the fuel gas flow path 3 included in the first flow path portion 23a is more It is good also as a structure where a flow-path cross-sectional area becomes larger than the fuel gas flow path 3 which the 2nd flow-path part 23b has.

  At least the total of the cross-sectional areas of the fuel gas flow paths 3 included in the second flow path section 23b is smaller than the total of the cross-sectional areas of the fuel gas flow paths 3 included in the first flow path section 23a. As described above, the number of fuel gas flow paths 3 and the cross-sectional area of the flow paths are set as appropriate. In particular, the number of fuel gas passages 3 and the cross-sectional area of the fuel gas passages 3 can be appropriately set so that the flow rate of the fuel gas is more uniform across the first passage portion 23a and the second passage portion 23b. It is advantageous.

  However, from the viewpoint of actual manufacturing, it is preferable that the cross-sectional areas of the fuel gas flow paths 3 constituting the first flow path portion 23a and the second flow path portion 23b are all the same for the first separator 2a. Design and fabrication are easy. For this reason, the flow passage cross-sectional areas of the fuel gas flow passages 3 constituting the first flow passage portion 23a and the second flow passage portion 23b are the same, and the number of the fuel gas flow passages 3 constituting the first flow passage portion 23a, The configuration in which the number of the fuel gas flow paths 3 constituting the second flow path portion 23b is different is advantageous in designing and manufacturing.

(Modification 1)
Next, with reference to FIG. 3, the 1st separator 2a with which the fuel cell 100 which concerns on the modification 1 of embodiment of this invention is provided is demonstrated. FIG. 3 is a plan view showing a schematic configuration of the first separator 2a included in the fuel cell 100 according to Modification 1 of the embodiment of the present invention. 3, the main surface of the first separator 2a on the side in contact with the fuel electrode 11 is illustrated.

  The first separator 2a according to Modification 1 is different from the first separator 2a according to the present embodiment shown in FIG. 2 in that two inlet manifolds 21 are provided. The fuel gas supplied from each of the two inlet manifolds 21a and 21b flows through the first flow path portions 23a1 and 23a2, is merged at the gas merge section 24, and is led to the second flow path section 23b. . Since the 1st separator 2a with which the fuel cell 100 which concerns on the modification 1 is provided other than that is the same as the 1st separator 2a with which the fuel cell 100 which concerns on embodiment is provided, the same code | symbol is attached | subjected to the same member. The description is omitted.

  As shown in FIG. 3, in the first separator 2 a according to the first modification, a plurality of (two in the example of FIG. 3) inlet manifolds 21 a and 21 b are provided on one side of the main surface in contact with the fuel electrode 11. An outlet manifold 22 is provided. Moreover, the gas confluence | merging part 24 is provided in the side opposite to this one side.

  More specifically, on one side of the main surface of the first separator 2a that is in contact with the fuel electrode 11, an outlet manifold 22 is provided at the center of the one side. In addition, inlet manifolds 21a and 21b are respectively provided at positions where the outlet manifold 22 is sandwiched on each end side of the one side. Due to this arrangement relationship, the vicinity region portions of the inlet manifolds 21a and 21b where the heat generation amount of the cell 1 is large are disposed at both ends of one side, and the vicinity region portion of the outlet manifold 22 where the heat generation amount is small is disposed at the center portion. Can do. For this reason, variation in temperature distribution in the cell 1 can be suppressed.

  In addition, first flow path portions 23a1 and 23a2 each composed of five fuel gas flow paths 3 having substantially the same cross-sectional area and substantially linear shapes extend from the respective inlet manifolds 21a and 21b to the gas junction 24. doing. That is, a total of ten fuel gas passages 3 are connected from the inlet manifolds 21 a and 21 b to the gas junction 24.

  On the other hand, a second flow path portion 23b composed of five fuel gas flow paths 3 each having substantially the same cross-sectional area and substantially linear shape is disposed in parallel with the first flow path portion 23a, and a gas merging portion. 24 to the outlet manifold 22. That is, a total of five fuel gas passages 3 are connected from the gas junction 24 to the outlet manifold 22.

  In such a configuration of the first separator 2a, the fuel gas flowing from the two inlet manifolds 21a and 21b through the first flow path portion 23a merges at the gas merge section 24, and then the second flow path section 23b. Led to. Then, the fuel gas flows through the second flow path portion 23 b and is discharged from the outlet manifold 22.

  By the way, the fuel gas flow path 3 which comprises each of the 1st flow path part 23a and the 2nd flow path part 23b is a flow path which has the same flow-path cross-sectional area. As shown in FIG. 3, the second flow path portion 23b has fewer fuel gas flow paths 3 than the first flow path portion 23a. For this reason, the flow path cross-sectional area of the second flow path portion 23 b indicated by the total of the five fuel gas flow paths 3 is the flow path of the first flow path portion 23 a indicated by the total of the ten fuel gas flow paths 3. It becomes smaller than the cross-sectional area. That is, in the 1st separator 2a which concerns on the modification 1, the flow-path cross-sectional area of the outlet manifold 22 vicinity is half with respect to the flow-path cross-sectional area of the inlet manifolds 21a and 21b vicinity.

  Therefore, the fuel gas guided from the gas merging portion 24 to the second flow path portion 23b can increase the flow velocity again, and the fuel gas flow velocity across the first flow path portion 23a and the second flow path portion 23b. Can be made uniform. For this reason, the fall of the electric power generation amount and the emitted-heat amount of the cell 1 in the downstream of the 2nd flow-path part 23b can be suppressed.

  Furthermore, the two inlet manifolds 21a and 21b and the outlet manifold 22 are provided on the same side (on the left side in the example of FIG. 3) of the main surface of the first separator 2a on the side in contact with the fuel electrode 11. . An inlet manifold 21a and an inlet manifold 21b are arranged in the vertical direction so as to sandwich the outlet manifold 22. Thus, in the cell 1, the region where the power generation amount and the heat generation amount are smaller is arranged in the center, and the region is sandwiched between the regions where the power generation amount and the heat generation amount are larger.

  Further, in the first separator 2a, the second flow path portion 23b is arranged in the center on the main surface in contact with the fuel electrode 11, and is sandwiched in the vertical direction by the two first flow path portions 23a1 and 23a2. Has been placed. Then, the amount of heat generated in the reaction surface of the cell 1 gradually decreases from each of the inlet manifolds 21a and 21b toward the gas merging portion 24 (from the left to the right in FIG. 3). Further, it further decreases from the gas junction 24 toward the outlet manifold 22 (from the right to the left in FIG. 3). Thus, since the position where the calorific value is high and the position where the heat generation amount is low are arranged adjacent to each other in the reaction surface of the cell 1, variations in the temperature distribution of the cell 1 can be suppressed.

  Therefore, in the fuel cell 100 according to the first modification of the present embodiment, the variation in the temperature distribution in the reaction surface of the cell 1 can be reduced, and therefore the occurrence of cracks or cracks in the cell 1 can be prevented. it can. Therefore, the fuel cell 100 can obtain high reliability.

  In the first separator 2a according to the first modification of the present embodiment, the first flow path portions 23a1 and 23a2 are configured by a total of 10 fuel gas flow paths 3, and the second flow path portions 23b are 5 lines. However, the number of the fuel gas flow paths 3 included in each of the first flow path portions 23a1 and 23a2 and the second flow path portion 23b is not limited to this. Moreover, although the flow-path cross-sectional area of the fuel gas flow path 3 which each of the 1st flow-path part 23a1, 23a2 and the 2nd flow-path part 23b has was substantially equal, it is not limited to this. For example, in the first separator 2a, the number of the fuel gas flow paths 3 combined in each of the first flow path portions 23a1 and 23a2 and the number of the fuel gas flow paths 3 included in the second flow path portion 23b are both equal. The fuel gas flow paths 3 included in the first flow path portions 23a1 and 23a2 may be configured to have a flow path cross-sectional area larger than that of the fuel gas flow paths 3 included in the second flow path portion 23b.

  At least the total of the cross-sectional areas of the fuel gas flow paths 3 included in the second flow path portion 23b is smaller than the total of the cross-sectional areas of the fuel gas flow paths 3 included in the first flow path portions 23a1 and 23a2. The number of fuel gas flow paths 3 and the cross-sectional area of the flow paths are set as appropriate so that the relationship is established. In particular, the number of fuel gas flow paths 3 and the cross-sectional area of the flow paths are appropriately set so that the flow rate of the fuel gas is more uniform across the first flow path portions 23a1, 23a2 and the second flow path portion 23b. It is advantageous.

  However, from the viewpoint of actual manufacturing, it is preferable that the first gas separators 23a1 and 23a2 and the second gas flow path part 23b have the same flow path cross-sectional area of the fuel gas flow path 3 as the first separator. 2a can be easily designed and manufactured. For this reason, the fuel gas flow paths constituting the first flow path portions 23a1 and 23a2 are made the same in the cross sectional areas of the fuel gas flow paths 3 constituting the first flow path portions 23a1 and 23a2 and the second flow path portions 23b, respectively. 3 and the number of fuel gas flow paths 3 constituting the second flow path portion 23b are more advantageous in designing and manufacturing.

(Modification 2)
Next, with reference to FIG. 4, the 1st separator 2a with which the fuel cell 100 which concerns on the modification 2 of embodiment of this invention is provided is demonstrated. FIG. 4 is a plan view showing a schematic configuration of the first separator 2a included in the fuel cell 100 according to Modification 2 of the embodiment of the present invention. 4, the main surface of the first separator 2a on the side in contact with the fuel electrode 11 is illustrated.

  As shown in FIG. 4, the first separator 2 a according to the second modification example has the first separator 2 a according to the first modification example described above so that the central portion in the horizontal direction is line-symmetric with respect to the axis extending in the vertical direction. The inlet manifolds 21a and 21b are shared.

  That is, the first separator 2a according to the modified example 2 includes two inlet manifolds 21a and 21b, an outlet manifold 22 disposed so as to be sandwiched therebetween, two gas merging portions 24a and 24b, and four first flow streams. It is the structure provided with path part 23a1, 23a2, 23a3, 23a4 and two 2nd flow-path part 23b1, 23b2. In the first separator 2a according to the modified example 2, the number of each of the first flow path parts 23a1, 23a2, 23a3, 23a4, the gas merging parts 24a, 24b, and the second flow path parts 23b1, 23b2 is the first according to the modified example 1. Although different from the separator 2a, the description is omitted because it is the same except that the number of separators is different.

  In FIG. 4, two inlet manifolds 21 a and 21 b are arranged in the vertical direction so as to sandwich the outlet manifold 22 in the central portion in the horizontal direction. Moreover, the gas confluence | merging part 24a is provided in the left side of the 1st separator 2a shown in FIG. 4, and the gas confluence | merging part 24b is each provided in the right side of the 1st separator 2a shown in FIG.

  Further, the first flow path portion 23a1 extends from the inlet manifold 21a in the left direction in FIG. 4 toward the gas merge portion 24a, and the first flow path portion 23a2 extends in the right direction in FIG. 4 toward the gas merge portion 24b. Yes. Similarly, the first flow path portion 23a3 extends from the inlet manifold 21b toward the gas merge portion 24a in the left direction in FIG. 4, and the first flow path portion 23a4 extends in the right direction toward the gas merge portion 24b.

  Each of the first flow path portions 23a1, 23a2, 23a3, and 23a4 is composed of five fuel gas flow paths 3 having substantially the same cross-sectional area and substantially linear shapes. The first flow path portions 23a1, 23a2, 23a3, and 23a4 configured by the five fuel gas flow paths 3 communicate with the inlet manifolds 21a and 21b as described above at one end thereof, and on the opposite side. The end portion communicates with the gas merging portions 24a and 24b.

  The gas joining part 24a communicates with the first flow path parts 23a1 and 23a3 and also communicates with the second flow path part 23b1. Further, the gas junction 24b communicates with the first flow path portions 23a2 and 23a4 and also communicates with the second flow path portion 23b2.

  A second flow path portion 23b1 extends in the lateral direction from the gas confluence portion 24a toward the outlet manifold 22 and in parallel with the first flow path portions 23a1 and 23a3. Further, the second flow path portion 23b2 extends in the lateral direction from the gas confluence portion 24b toward the outlet manifold 22 and in parallel with the first flow path portions 23a2 and 23a4.

  Each of the second flow path portions 23b1 and 23b2 is composed of five fuel gas flow paths 3 having substantially the same cross-sectional area and substantially linear shapes. And the second flow path part 23b1 composed of the five fuel gas flow paths 3 has the first flow path parts 23a1 and 23a3 at the ends on the same side as the one side communicating with the inlet manifolds 21a and 21b. It communicates with the outlet manifold 22. Similarly, the second flow path portion 23b2 composed of the five fuel gas flow paths 3 has the first flow path portions 23a2 and 23a4 at the end portions on the same side as one side communicating with the inlet manifolds 21a and 21b. , Communicated with the outlet manifold 22.

  The fuel gas channel 3 constituting each of the first channel parts 23a1, 23a2, 23a3 and 23a4 and the fuel gas channel 3 constituting each of the second channel parts 23b1, 23b2 have the same channel cross-sectional area. ing.

  In the configuration described above, the fuel gas supplied from the inlet manifold 21a flows separately into the first flow path portion 23a1 and the first flow path portion 23a2. The fuel gas that has flowed through the first flow path portion 23a1 is merged at the gas merge portion 24a and is guided to the second flow path portion 23b1. On the other hand, the fuel gas that has flowed through the first flow path portion 23a2 is merged at the gas merge section 24b and guided to the second flow path portion 23b2. Further, the fuel gas supplied from the inlet manifold 21b flows separately into the first flow path portion 23a3 and the first flow path portion 23a4. The fuel gas that has flowed through the first flow path portion 23a3 merges at the gas merge section 24a and is guided to the second flow path portion 23b1. On the other hand, the fuel gas that has flowed through the first flow path portion 23a4 is merged at the gas merge section 24b and guided to the second flow path portion 23b2.

  As described above, the first separator 2a according to the modified example 2 has five fuel gas passages through which the fuel gas that has flowed through the first passage portions 23a1 and 23a3 composed of the ten fuel gas passages 3 in total. 3 circulates through the second flow path portion 23b1. Further, the fuel gas that has flowed through the first flow path portions 23 a 2 and 23 a 4 constituted by a total of 10 fuel gas flow paths 3 flows through the second flow path portion 23 b 2 constituted by five fuel gas flow paths 3.

  That is, in the first separator 2a according to the modified example 2, the flow path cross-sectional area in the vicinity of the outlet manifold 22 is halved relative to the flow path cross-sectional area in the vicinity of the inlet manifolds 21a and 21b.

  Therefore, the fuel gas guided from the gas merging portion 24 to the second flow path portion 23b can increase the flow velocity again, and the fuel gas flow velocity across the first flow path portion 23a and the second flow path portion 23b. Can be made uniform. For this reason, the fall of the electric power generation amount and the emitted-heat amount of the cell 1 can be suppressed also in the downstream of the 2nd flow-path part 23b.

  Furthermore, the two inlet manifolds 21a and 21b and the outlet manifold 22 are located at a substantially central portion in the lateral direction of the main surface of the first separator 2a. And the inlet manifold 21a and the inlet manifold 21b are provided in the vertical direction in the position which pinches | interposes the outlet manifold 22. As shown in FIG. Thus, in the cell 1, the region where the power generation amount and the heat generation amount are smaller is arranged in the center, and the region is sandwiched between the regions where the power generation amount and the heat generation amount are larger.

  Moreover, in the 1st separator 2a which concerns on the modification 2, the 2nd flow-path part 23b1 is arrange | positioned in the center in the main surface on the side which contact | connects the fuel electrode 11, and it is comprised by the 1st flow-path part 23a1 and the 1st flow-path part 23a3. It is arranged so as to be sandwiched in the vertical direction. Further, the second flow path portion 23b2 is disposed so as to be sandwiched between the first flow path portion 23a2 and the first flow path portion 23a4 in the vertical direction.

  With this configuration, the position where the heat generation amount is high and the position where the heat generation amount is low can be adjacent to each other in the reaction surface of the cell 1, so that variation in the temperature distribution of the cell 1 can be suppressed.

  Therefore, in the fuel cell 100 according to the second modification of the present embodiment, the variation in the temperature distribution in the reaction surface of the cell 1 can be reduced, so that it is possible to prevent the cell 1 from being cracked or cracked. it can. Therefore, the fuel cell 100 can obtain high reliability.

  In the first separator 2a according to the second modification of the present embodiment, the first flow path portions 23a1, 23a2, 23a3, and 23a4 are composed of a total of 20 fuel gas flow paths 3, and the second flow path portion. 23b1 and 23b2 are composed of 10 fuel gas passages 3 in total, but the fuel gas passages 3 included in the first passage portions 23a1, 23a2, 23a3 and 23a4 and the second passage portions 23b1 and 23b2 respectively. The number of is not limited to this. In addition, the first gas flow path portions 23a1, 23a2, 23a3, 23a4, and the second flow path portions 23b1, 23b2 respectively have substantially the same cross-sectional area of the fuel gas flow path 3, but the present invention is limited to this. It is not a thing.

  For example, in the first separator 2a, the number of fuel gas passages 3 obtained by adding the first passage portions 23a1 and 23a3 and the number of fuel gas passages 3 included in the second passage portion 23b1 are both the same. The fuel gas flow paths 3 included in the first flow path portions 23a1 and 23a3 may be configured to have a flow path cross-sectional area larger than that of the fuel gas flow path 3 included in the second flow path portion 23b1.

  Similarly, the first separator 2a has the same number of both the number of the fuel gas flow paths 3 obtained by adding the first flow path portions 23a2 and 23a4 and the number of the fuel gas flow paths 3 included in the second flow path portions 23b2. In addition, the fuel gas flow paths 3 included in the first flow path portions 23a2 and 23a4 may be configured to have a flow path cross-sectional area larger than that of the fuel gas flow path 3 included in the second flow path portion 23b2.

  That is, at least the total of the cross-sectional areas of the fuel gas flow paths 3 included in the second flow path portion 23b1 is greater than the total of the cross-sectional areas of the fuel gas flow paths 3 included in the first flow path portions 23a1 and 23a3. The number of the fuel gas flow paths 3 and the cross-sectional area of the flow paths are appropriately set so that the relationship becomes smaller. Further, the sum of the cross-sectional areas of the fuel gas flow paths 3 included in the second flow path portion 23b2 is smaller than the total of the cross-sectional areas of the fuel gas flow paths 3 included in the first flow path portions 23a2 and 23a4. The number of the fuel gas flow paths 3 and the cross-sectional area of the flow paths are set as appropriate so that the relationship is established.

  In particular, the number of the fuel gas flow paths 3 and the cross-sectional area of the flow paths are appropriately set so that the flow rate of the fuel gas is more uniform over the first flow path portions 23a1 to 23a4 and the second flow path portions 23b1 and 23b2. , It is advantageous to set.

  However, in terms of actual manufacturing, it is more preferable that the cross-sectional areas of the fuel gas flow paths 3 constituting the first flow path portions 23a1 to 23a4 and the second flow path portions 23b1 and 23b2 are the same. One separator 2a can be easily designed and manufactured. For this reason, the flow passage cross-sectional areas of the fuel gas flow passages 3 constituting the first flow passage portions 23a1 to 23a4 and the second flow passage portions 23b1 and 23b2 are made the same, and the number of the fuel gas flow passages 3 included in each is different. This configuration is advantageous in designing and manufacturing.

  By the way, since a cell is easily cracked due to thermal strain or the like, it cannot generally have a large area. Therefore, when configuring a large-area cell, the cell 1 included in the fuel cell 100 according to the present embodiment, the cell 1 included in the fuel cell 100 according to Modification 1, or the cell included in the fuel cell according to Modification 2. A plurality of 1 may be prepared and arranged side by side on one surface. When comprised in this way, it is good also as a structure which prepares several 1st separator 2a provided according to the cell 1 similarly, and arranges it in one surface.

  More specifically, as illustrated in FIG. 5, for example, the first separator 2 a included in the fuel cell 100 according to Modification 1 may be configured to be arranged in two in the horizontal direction and two in the vertical direction. FIG. 5 is a plan view showing an example of a schematic configuration in which a plurality of first separators 2 a provided in the fuel cell 100 according to the first modification of the embodiment of the present invention are arranged on one surface. 5, the main surface of the first separator 2a on the side in contact with the fuel electrode 11 is illustrated.

  In addition, in FIG. 5, although illustrated about the structure which arrange | positions the 1st separator 2a which concerns on the modification 1 on the 1st surface, the 1st separator 2a which concerns on embodiment, or the 1st separator 2a which concerns on the modification 2 is shown. A configuration may be adopted in which a plurality of sheets are arranged on one surface.

  As described above, the structure of the first separator 2a according to the embodiment, the first separator 2a according to the first modification, or the first separator 2a according to the second modification has the fuel gas consumption as the fuel gas is consumed by power generation. This is effective when the volume of the material decreases. This is effective in a fuel cell including a cell having an electrolyte that conducts protons.

  Moreover, the first separator 2a according to the embodiment, the first separator 2a according to the first modification example, or the first separator 2a according to the second modification example can suppress variations in temperature distribution in the cell 1. For this reason, the first separator 2a according to the embodiment, the first separator 2a according to the first modification example, or the first separator 2a according to the second modification example has an internal stress due to thermal expansion when the temperature distribution varies in the cell. This produces an excellent effect in a solid oxide fuel cell in which cracks or cracks may occur. In particular, the greatest effect can be achieved in a solid oxide fuel cell using an electrolyte of a proton conductor.

  Further, a fuel cell system is assembled by using the cell stack 40 formed by laminating the cell 1, the first separator 2a according to the first modified example or the first separator 2a according to the second modified example, and the second separator 2b. But you can. For example, when such a fuel cell system is assembled, as shown in FIG. 6, the fuel cell system includes a gas introduction pipe 30 that introduces fuel gas into the fuel gas passage 3 and air that introduces air into the air passage 4. It is good also as a structure provided with the introduction pipe | tube 31. FIG. FIG. 6 is a perspective view schematically showing an example of a fuel cell system including the fuel cell 100 according to Modification 1 or Modification 2 of the embodiment of the present invention.

  In the fuel cell system, as shown in FIG. 6, the gas introduction pipe 30 includes a plurality of branch pipes 30 a for equally distributing the supplied fuel gas to the inlet manifolds 21 a and 21 b outside the cell stack 40. It can be set as the structure with 30b. Such a configuration is advantageous in that the fuel gas can be distributed with a simpler structure than the structure in which the fuel gas is equally distributed in the cell stack 40.

  From the foregoing description, many modifications and other embodiments of the present invention are obvious to one skilled in the art. Accordingly, the foregoing description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the structure and / or function may be substantially changed without departing from the spirit of the invention.

  The fuel cell according to the present invention improves the uniformity of the fuel gas flow rate, and suppresses the variation in temperature distribution in the cell and prevents the cell from cracking by reducing the physical distance between the inlet manifold and the outlet manifold. be able to. Therefore, the present invention can be widely applied to fuel cells in which cells are cracked due to variations in temperature distribution in the cells.

1 cell 2 separator 2a first separator 2b second separator 3 fuel gas flow path 4 air flow path 10 electrolyte 11 fuel electrode 12 air electrode 21 inlet manifold 21a inlet manifold 21b inlet manifold 22 outlet manifold 23a first flow path portion 23a1 first flow path Part 23a2 first flow path part 23a3 first flow path part 23a4 first flow path part 23b second flow path part 23b1 second flow path part 23b2 second flow path part 24 gas merging part 24a gas merging part 24b gas merging part 30 gas introduction pipe 30a Branch pipe 30b Branch pipe 40 Cell stack 100 Fuel cell

Claims (6)

A flat cell composed of an electrolyte sandwiched between a fuel electrode and an air electrode;
A flat plate-shaped first separator disposed on the fuel electrode side and a flat plate-shaped second separator disposed on the air electrode side, sandwiching the cell,
The first separator is
An inlet manifold to which fuel gas is supplied;
An outlet manifold through which the fuel gas is discharged;
A first flow path portion that is formed on a main surface in contact with the fuel electrode, communicates with the inlet manifold at an end portion on one side, and circulates fuel gas supplied from the inlet manifold;
A gas merging section for merging the fuel gas flowing through the first flow path section;
Formed on the main surface, arranged in parallel with the first flow path portion, communicated with the outlet manifold at an end portion on the same side as the one end portion of the first flow path portion, and at the gas confluence portion A second flow path portion for flowing the merged fuel gas toward the outlet manifold,
The fuel cell, wherein a cross-sectional area of the second flow path portion is smaller than a cross-sectional area of the first flow path portion. The first flow path part and the second flow path part are composed of a plurality of fuel gas flow paths through which fuel gas flows, the flow path cross-sectional areas being equal and linear.
2. The fuel cell according to claim 1, wherein the first flow path section has a larger number of the fuel gas flow paths than the second flow path section.   The fuel cell according to claim 1, wherein the electrolyte is a proton conductor made of a solid oxide. The cell and the first separator are rectangular,
2. The plurality of inlet manifolds and the outlet manifold are provided on one side of the main surface of the first separator, and the gas merging portion is provided on a side opposite to the one side. 4. The fuel cell according to any one of items 1 to 3. On one side of the main surface of the first separator,
The inlet manifold is provided on each of both ends of the one side,
The fuel cell according to claim 4, wherein the outlet manifold is provided at a position that is a central portion between the inlet manifolds provided on both ends of the one side and is sandwiched by the inlet manifold. A cell stack formed by laminating the cell, the first separator, and the second separator included in the fuel cell according to claim 4 or 5,
A gas introduction pipe for introducing fuel gas into the plurality of inlet manifolds,
The gas introduction pipe is a fuel cell system having a plurality of branch pipes for equally distributing the supplied fuel gas to the plurality of inlet manifolds.

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