JP2015220022A - Fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell in which temperature distribution can be reduced in the surface direction of unit cell, without blocking reaction gas supply to an electrode.SOLUTION: Between a fuel electrode surface 23a and a separator 3, a heat conduction member 9 having an effective heat conductivity per unit cross-sectional area higher than those of a fuel electrode 23 and the separator 3 is arranged. The heat conduction member 9 is extended in the fuel gas flow direction, and arranged to form a space in which the reaction gas flows between itself and the fuel electrode surface 23a. With such an arrangement, heat of a unit cell 2 can be moved to the heat conduction member 9, with the fuel gas as a medium, thence moved in the fuel gas flow direction, in the heat conduction member 9. According to the invention, temperature distribution can be reduced in the surface direction of the unit cell 2, without blocking reaction gas supply to the fuel electrode 23.

Description

  The present invention relates to a solid oxide fuel cell (SOFC) using an electrolyte composed of a solid oxide.

  As a fuel cell of this type, a flat plate type in which a plurality of flat single cells are stacked is known (see, for example, Patent Document 1). This flat single cell has a flat electrolyte, a flat air electrode provided on one surface of the electrolyte, and a flat fuel electrode provided on the other surface of the electrolyte.

  The flat plate type fuel cell has a structure in which a reaction gas is supplied to a single cell in parallel to the surface of the single cell. Specifically, the fuel gas flow path for supplying the fuel gas to the fuel electrode by the flow path forming member disposed facing the fuel electrode surface faces the fuel electrode surface and is parallel to the fuel electrode surface. It is formed to extend. As a result, the fuel gas flowing parallel to the fuel electrode surface in the fuel gas channel diffuses from the fuel electrode surface toward the electrolyte side, and the electrochemical reaction (power generation reaction) occurs in the reaction layer on the electrolyte side of the fuel electrode. ) Occurs.

  Patent Document 1 describes a structure in which a flat plate-like heat conduction layer is arranged directly on the fuel electrode surface in a flat plate type fuel cell.

JP 2004-22471 A

  By the way, in the flat plate type fuel cell, the fuel gas concentration of the fuel gas flow channel facing the single cell is high in the central part in the fuel gas flow direction and goes from the central part to the downstream side due to the consumption of the fuel gas by the power generation reaction. As it gets lower. For this reason, the single cell has a temperature distribution in which the temperature is highest in the center portion in the fuel gas flow direction, and the temperature becomes lower toward the downstream side than the center portion in the fuel gas flow direction. If this temperature distribution is large, that is, if the difference between the maximum temperature and the minimum temperature is large, cell cracking occurs due to thermal stress. Therefore, it is necessary to reduce the temperature distribution (temperature difference) in the plane direction of the single cell.

  Therefore, as a method for reducing the temperature distribution, it is conceivable to use a heat conducting member as in Patent Document 1. Specifically, a plate-like heat conducting member that conducts heat more easily than the fuel electrode is brought into contact with the surface of the fuel electrode. At this time, the contact portion of the heat conducting member with the fuel electrode has a planar shape, and the contact area between the fuel electrode surface and the heat conducting member is increased so that the heat resistance (contact resistance) between the fuel electrode and the heat conducting member is increased. Make it as small as possible. Thereby, it is conceivable that the heat of the single cell is moved directly from the fuel electrode to the heat conducting member, and the heat is moved in the surface direction of the single cell within the heat conducting member.

  However, in this case, since the entire region facing the heat conducting member on the surface of the fuel electrode is directly covered with the heat conducting member, the supply of the fuel gas from the fuel gas channel is hindered. For this reason, compared with the case where a heat conduction member is not used, the problem that the electric power generation output of a single cell will fall arises.

  In addition, as a method for reducing the temperature distribution in the plane direction of the single cell, it is also conceivable to bring a flat heat conductive member into contact with the air electrode surface. However, in this case as well, the portion of the air electrode surface that faces the heat conducting member is directly covered by the heat conducting member, which causes a problem that the supply of air from the air flow path is hindered.

  The present invention has been made in view of the above points, and an object thereof is to provide a fuel cell that can reduce the temperature distribution in the plane direction of a single cell without hindering the supply of the reaction gas to the electrode.

  As a result of calculating the thermal conductance in the conventional flat single cell from the thermal circuit model, the inventor of the present application shows that the thermal conductance between the cell and the fuel gas in the direction perpendicular to the single cell surface is parallel to the single cell surface. It was found that it was overwhelmingly larger than the thermal conductance inside the single cell in the direction (see FIG. 6), and the present invention was created. The thermal conductance means the ease of heat transfer and is represented by the reciprocal of thermal resistance.

That is, in order to achieve the above object, in the invention described in claim 1,
A plate-shaped electrolyte (21) composed of a solid oxide and having a main surface;
Plate-like electrodes (22, 23) provided on the main surfaces (21a, 21b) of the electrolyte and having electrode surfaces (22a, 23a) on the side opposite to the electrolyte side;
A flow path forming member (3) disposed opposite to the electrode surface and forming a reactive gas flow path (6, 7) between which the reactive gas flows parallel to the electrode surface;
A heat conductive member (9) disposed between the electrode surface and the flow path forming member and having a higher effective thermal conductivity per unit cross-sectional area than the electrode and the flow path forming member;
The heat conducting member extends in the reaction gas flow direction and is characterized in that a space through which the reaction gas flows is formed between the heat conduction member and the electrode surface.

  According to this, a space through which the reaction gas flows is formed between the heat conducting member and the electrode surface, and the region facing the heat conducting member on the electrode surface is not directly covered by the heat conducting member. The supply of the reaction gas to the electrode is not hindered by the conductive member.

  Further, the thermal conductance between the single cell configured with the electrolyte and the electrode and the reaction gas is larger than the thermal conductance inside the single cell. Therefore, according to the present invention, the heat of the single cell can be moved to the heat conducting member using the reaction gas as a medium, and the heat can be moved in the direction of the reaction gas flow in the heat conducting member.

  Therefore, according to the present invention, the temperature distribution in the plane direction of the single cell can be reduced without hindering the supply of the reaction gas to the electrodes.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

It is a schematic diagram which shows the fuel cell of the stack structure in 1st Embodiment. It is a bottom view of the separator arrange | positioned between the single cells of FIG. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. FIG. 4 is a cross-sectional view taken along line IV-IV in FIGS. 2 and 3. 6 is a cross-sectional view of a single cell and a separator in Comparative Example 1. FIG. It is a figure which shows the thermal circuit model of the laminated structure of the single cell and separator of the comparative example 1. It is the analysis result of the temperature distribution of the single cell about each of 1st Embodiment and Comparative Example 1. FIG. It is sectional drawing of the single cell and separator in 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be described with the same reference numerals.

(First embodiment)
The fuel cell 1 of this embodiment is a solid oxide fuel cell (SOFC). As shown in FIG. 1, a fuel cell 1 includes a flat plate in which a plurality of flat single cells 2 that output electric energy by an electrochemical reaction between a fuel gas and an oxidant gas (air in this embodiment) are vertically stacked. It is composed of a stacked stack structure. A plurality of single cells 2 are stacked via separators 3 shown in FIG.

  As shown in FIGS. 3 and 4, the single cell 2 includes a flat electrolyte 21 having one surface (upper surface in the present embodiment) 21 a and another surface (lower surface 21 b in the present embodiment), and one surface 21 a side of the electrolyte 21. A flat oxidant electrode (air electrode in this embodiment) 22 provided and a flat fuel electrode 23 provided on the other surface 21 b side of the electrolyte 21 are provided. The air electrode 22 is a cathode electrode, and the fuel electrode 23 is an anode electrode.

  The electrolyte 21 is composed of an oxide ion conductor having a function of conducting oxide ions from the air electrode 22 side to the fuel electrode 23 side. As the electrolyte 21, one made of a solid oxide (ceramics) such as yttria stabilized zirconia (YSZ) can be adopted. One surface 21 a and the other surface 21 b of the electrolyte 21 are two main surfaces of the electrolyte 21 in parallel.

  The air electrode 22 is composed of a porous body having conductivity that allows a reaction gas (oxidant gas) to pass to the electrolyte 21. As the air electrode 22, one made of lanthanum strontium cobalt iron oxide (LSCF) or the like can be adopted. The air electrode 22 has an electrode surface (air electrode surface) 22 a parallel to the one surface 21 a of the electrolyte 21 on the side opposite to the electrolyte side.

  The fuel electrode 23 is composed of a porous body having conductivity that allows a reaction gas (fuel gas) to pass to the electrolyte 21. As the fuel electrode 23, for example, a material composed of cermet (Ni-YSZ) of nickel (Ni) and yttria stabilized zirconia (YSZ) can be employed. The fuel electrode 23 has an electrode surface (fuel electrode surface) 23a parallel to the other surface 21b of the electrolyte 21 on the side opposite to the electrolyte side.

  The single cell 2 is supported by a flat frame 4. The frame 4 is joined to the outer peripheral edge of the single cell 2 via a glass sealing material 5. In the present embodiment, the frame 4 divides a space between a pair of separators 3 described later into an air flow path 6 and a fuel gas flow path 7. The frame 4 is made of a metal material such as stainless steel. The frame 4 may be made of a conductive material other than a metal material such as conductive ceramics.

  As shown in FIG. 3, the separator 3 is disposed to face the electrode surfaces 22 a and 23 a of the single cell 2, and the reaction gas flows between the electrode surfaces 22 a and 23 a in parallel with the electrode surfaces 22 a and 23 a. The flow path forming member forms the flow paths 6 and 7 for each single cell 2, and separates the reaction gas flow paths 6 and 7 of the adjacent single cells 2. Note that the direction perpendicular to the paper surface in FIG. 3 is the flow direction of the reaction gas. Moreover, the separator 3 is comprised with metal materials, such as stainless steel, and has electrically connected the electrodes of the adjacent single cell 2. FIG. The separator 3 may be made of a conductive material other than a metal material such as conductive ceramics.

  Specifically, as shown in FIGS. 3 and 4, the separator 3 is arranged so that a single cell 2 is sandwiched between a pair of separators 31 and 32. A fuel gas flow path 7 in which the fuel gas flows is formed between the lower separator 32 positioned below the single cell 2 and the fuel electrode 23 and the frame 4 of the single cell 2.

  As shown in FIG. 4, the fuel gas channel 7 includes a surface side channel 7 a facing the fuel electrode surface 23 a, an upstream channel 7 b positioned upstream of the fuel gas flow with respect to the fuel electrode 23, and a fuel electrode. 23 and a downstream flow path 7c located downstream of the fuel gas flow. The upstream flow path 7b, the surface flow path 7a, and the downstream flow path 7c all extend in parallel to the fuel electrode surface 23a, and the fuel gas flows through each flow path in parallel to the fuel electrode surface 23a. It has become.

  The surface-side flow path 7 a is a flow path constituted by a space formed between the fuel electrode surface 23 a and the lower separator 32. Moreover, facing the fuel electrode surface 23a means facing the fuel electrode surface 23a. The upstream flow path 7b is a flow path constituted by a space formed between the frame 4 and the lower separator 32 on the fuel gas inlet side (left side in FIG. 4) of the separator 3 (not shown). The downstream flow path 7c is a flow path constituted by a space formed between the frame 4 and the lower separator 32 on the fuel gas outlet side (right side in FIG. 4) of the separator 3 (not shown).

  The surface side flow path 7a communicates directly with the upstream flow path 7b and the downstream flow path 7c. For this reason, as shown by the arrows in FIG. 4, the fuel gas flows in parallel to the fuel electrode surface 23a in the order of the upstream channel 7b, the surface channel 7a, and the downstream channel 7c.

  Further, as shown in FIG. 3, the lower separator 32 has a concavo-convex shape, and by this concavo-convex shape, a plurality of surface-side flow paths 7a are formed and electrically connected to the fuel electrode surface 23a. A plurality of current collectors 8 are formed.

  Specifically, as shown in FIG. 2, the separator 3 (lower separator 32) is formed with a convex portion 3b protruding from the lower surface 3a. The convex portions 3b extend in one direction (left and right direction in FIG. 2), and a plurality of the convex portions 3b are arranged in a direction perpendicular to the extending direction (up and down direction in FIG. 2). The convex portion 3b constitutes a concave portion 3d on the upper surface 3c of the separator 3 (see FIGS. 3 and 4). The recess 3d is formed in the separator 3 at a position facing the fuel electrode 23 (see FIGS. 3 and 4).

  As shown in FIG. 3, the upper surface 3c of the separator 3 (lower separator 32) is in contact with the fuel electrode surface 23a, and a plurality of recesses 3d provided on the upper surface 3c of the separator 3 and the fuel electrode surface 23a. Thus, a plurality of surface-side flow paths 7a extending in parallel in one direction are formed. The portion of the separator 3 that is in contact with the fuel electrode surface 23 a is the current collector 8.

  For this reason, the fuel gas flowing in the upstream flow path 7b is distributed from the upstream flow path 7b to the plurality of surface side flow paths 7a, and the fuel gas that has passed through the plurality of surface side flow paths 7a is the downstream flow path 7c. It flows into and joins.

  As shown in FIG. 3, an air flow path 6 through which air flows is formed between the upper separator 31 positioned above the single cell 2, the air electrode 22 of the single cell 2, and the frame 4. FIG. 3 shows the air flow path 6 formed between the upper separator 31 and the air electrode 22.

  Similar to the fuel gas flow path 7, the air flow path 6 includes a surface-side flow path 6 a that faces the air electrode surface 22 a and an upstream-side flow path (not shown) that is located upstream of the air electrode 22. And a downstream channel (not shown) located on the downstream side of the air flow with respect to the air electrode 22. The upstream flow path, the surface flow path 6a, and the downstream flow path of the air flow path 6 all extend in parallel to the air electrode surface 22a, and air flows in the flow paths in parallel to the air electrode surface 22a. It comes to flow.

  In the present embodiment, the upper separator 31 and the lower separator 32 have the same shape, and one type of shape is adopted as the separator 3. For this reason, like the lower separator 32, the upper separator 31 also has a concavo-convex shape, and by this concavo-convex shape, a plurality of surface-side flow paths 6a of the air flow path 6 are formed, and the air electrode surface 22a. A plurality of current collectors 8 that are electrically connected to each other are formed. For this reason, the air flowing in the upstream flow path of the air flow path 6 is distributed from the upstream flow path to the plurality of surface flow paths 6a, and the air that has passed through the plurality of surface flow paths 6a is the downstream flow path. It flows into and joins.

  In the present embodiment, the fuel gas supply direction and the air supply direction to each single cell 2, that is, the fuel gas flow direction in the fuel gas flow path 7 and the air flow direction in the air flow path 6 are opposite directions. (See FIG. 2). The fuel gas supply direction and the air supply direction to each single cell 2 may be the same direction.

  In the present embodiment, as shown in FIGS. 3 and 4, the heat conducting member 9 is disposed inside each of the plurality of front surface side flow paths 7 a formed by the separator 3. The heat conductive member 9 is a member having a higher effective thermal conductivity per unit cross-sectional area than the fuel electrode 23 and the separator 3. Since the effective thermal conductivity of the general fuel electrode 23 and the separator 3 is as small as 20.0 W / mK, the thermal conductive member 9 satisfies the following formula.

Effective thermal conductivity per unit cross-sectional area of the heat conducting member 9 = thermal conductivity of the substance × (100−cross section porosity (%)) / 100> 20.0 W / mK
In the present embodiment, a dense body made of Cu metal is employed as the heat conducting member 9. The heat conducting member 9 is not limited to Cu, and may be composed of other metals such as Ni and Ag.

  In this embodiment, the shape of the heat conducting member 9 is a cylinder. Therefore, the heat conducting member 9 is different from the separator 3 in shape and is separate from the separator 3. In addition, a different body means that a form differs. The heat conducting member 9 is provided in one surface side flow path 7a so that the axial direction of the cylinder coincides with the extending direction of the surface side flow path 7a (the fuel gas flow direction in the surface side flow path 7a). 9 are arranged one by one. Therefore, the heat conducting member 9 extends in the fuel gas flow direction in the surface-side flow path 7a.

  As shown in FIG. 3, the heat conducting member 9 is fixed to the separator 3 while being sandwiched between the fuel electrode surface 23 a and the separator 3. Therefore, a part of the surface of the heat conducting member 9 facing the fuel electrode 23 is in line contact with the fuel electrode surface 23a, and the other part of the surface of the heat conducting member 9 facing the fuel electrode 23 is from the fuel electrode surface 23a. It is separated. That is, the heat conduction member 9 forms gaps (spaces) 7 and 7a through which the fuel gas flows between the fuel electrode surface 23a except for the line contact portion with the fuel electrode surface 23a.

  4, the length of the heat conducting member 9 in the fuel gas flow direction is the same as the width of the fuel electrode 23 in the fuel gas flow direction, and one end 23c1 of the fuel electrode 23 in the fuel gas flow direction. To the other end 23c2. The heat conducting member 9 may be longer than the width of the fuel electrode 23 as long as it faces at least the range from the one end 23c1 to the other end 23c2 of the fuel electrode 23.

  In the fuel cell 1 of the present embodiment configured as above, oxygen in the air is supplied to the air electrode 22 of the single cell 2 by the air flowing through the air flow path 6, and the fuel gas flows through the fuel gas flow path 7. The fuel gas is supplied to the fuel electrode 23 of the single cell 2 by flowing.

By supplying hydrogen as the fuel gas, electric energy is output by the electrochemical reaction shown in the following reaction formulas (1) and (2).
<Fuel electrode (anode)>
2H ₂ + 2O ₂ ⁻ → 2H ₂ O + 4e ⁻ (1)
<Air electrode (cathode)>
O ₂ + 4e ⁻ → 2O ²⁻ (2)
Further, by supplying carbon monoxide (CO) as the fuel gas, electric energy is output by the electrochemical reaction shown in the following reaction formulas (3) and (4).
<Fuel electrode (anode)>
2CO + 2O ²⁻ → 2CO ₂ + 4e ⁻ (3)
<Air electrode (cathode)>
O ₂ + 4e ⁻ → 2O ²⁻ (4)
Next, features of the present embodiment will be described.

  First, the thermal circuit model of the laminated structure of the single cell and separator of Comparative Example 1 will be described. As shown in FIG. 5, the laminated structure of the cell and separator of Comparative Example 1 is obtained by omitting the heat conductive member 9 from the laminated structure of the cell and separator shown in FIGS. It is. The inventor calculated the thermal conductance in the laminated structure of the cell and separator of Comparative Example 1 from the thermal circuit model, and the result shown in FIG. 6 was obtained.

  In the thermal circuit model of the comparative example 1 shown in FIG. 6, the result of each thermal conductance C1-C11 calculated based on the physical property and shape of the single cell 2 is shown by the thickness of the line. Each thermal conductance C is the reciprocal of the thermal resistance R (C = 1 / R), and indicates that the thicker line is more likely to transfer heat than the thinner one. Moreover, the arrow in a thermal circuit shows the moving direction of heat.

  C1 is a thermal conductance related to the thermal conduction λ inside the single cell 2, C2 is a thermal conductance related to the contact resistance between the single cell 2 and the frame 4, and C3 is a thermal conductance related to the thermal conduction λ of the frame 4. C4 is the thermal conductance related to the air flow, and C5 and C6 are the thermal conductance related to the heat transfer α of the air. C7 is the thermal conductance related to the heat conduction λ inside the upper separator 31. C8 is the thermal conductance related to the fuel gas flow, and C9 and C10 are the thermal conductance related to the heat transfer α of the fuel gas. C11 is the thermal conductance related to the heat conduction λ inside the lower separator 32.

  As a result of calculating the thermal conductances C1 to C11, the thermal conductance C9 from the single cell 2 to the fuel gas and the thermal conductance C10 from the fuel gas to the lower separator 32 are perpendicular to the surface of the single cell 2. The thermal conductance of the single cell 2 is overwhelming than the thermal conductance in the direction parallel to the surface of the single cell 2 such as the thermal conductance C1 inside the single cell 2 and the thermal conductances C7 and C11 inside the upper and lower separators 31 and 32. It turned out to be big. This is because, in the flat unit cell 2 as in Comparative Example 1, the flow rate of the reaction gas (fuel gas) flowing through the reaction gas channel (fuel gas channel 7) is high, and the heat transfer of the reaction gas (fuel gas) is achieved. This is because the coefficient α is large. However, since the heat capacity of the fuel gas is small, when there is no heat conduction member near the fuel gas as in Comparative Example 1, the heat transfer from the single cell 2 is small, so the temperature distribution in the plane direction of the single cell 2 Was getting bigger.

  Therefore, in the present embodiment, the heat conducting member 9 is disposed inside the surface side flow path 7a of the fuel gas flow path 7, that is, between the fuel electrode surface 23a and the lower separator 32. At this time, the heat conducting member 9 is opposed to the range from the one end 23c1 to the other end 23c2 of the fuel electrode 23 in the fuel gas flow direction, and the fuel gas flows between the fuel electrode surface 23a and the heat conducting member 9. The heat conducting member 9 is arranged so as to form Thereby, the heat of the single cell 2 can be moved to the heat conducting member 9 using the fuel gas as a medium, and the heat can be moved in the direction of the fuel gas in the heat conducting member 9. That is, the heat of the single cell 2 can be moved in the fuel gas flow direction by heat transfer and heat conduction.

  Therefore, according to the present embodiment, as shown in the analysis result of the temperature distribution of the single cell in FIG. 7, the temperature difference inside the single cell in the fuel gas flow direction can be reduced as compared with Comparative Example 1. 7 uses the same thermal circuit model as in FIG. 6, from one end 23 c 1 to the other end 23 c 2 of the single cell 2 (fuel electrode 23) in the fuel flow direction in each of the present embodiment and Comparative Example 1. It is the result of having calculated the temperature in each position within the range. According to the result shown in FIG. 7, according to the present embodiment, the temperature difference ΔT1 between the maximum temperature and the minimum temperature of the single cell is compared with the temperature difference ΔT2 between the maximum temperature and the minimum temperature of the single cell in Comparative Example 1. The temperature difference ΔT2 can be reduced by about 80%.

  Further, although the heat conducting member 9 is in line contact with the fuel electrode surface 23a, the contact portion of the heat conducting member 9 with the fuel electrode surface 23a is not planar, so that the heat conducting member 9 has a contact with the fuel electrode surface 23a. It is not covered directly. Therefore, since the region facing the heat conducting member 9 in the fuel electrode surface 23 a is not directly covered by the heat conducting member 9, the supply of fuel gas to the fuel electrode 23 is not hindered by the heat conducting member 9.

  Incidentally, unlike the present embodiment, when a heat conducting member having a flat portion is brought into direct contact with the fuel electrode surface 23a, the contact resistance between the fuel electrode surface 23a and the heat conducting member must be reduced. For this purpose, it is necessary to increase the contact area, increase the load, decrease the surface roughness, and the like. On the other hand, according to this embodiment, since a space is formed between the fuel electrode surface 23a and the heat conducting member 9, these can be made unnecessary.

(Second Embodiment)
As shown in FIG. 8, the present embodiment is different from the first embodiment in that the heat conducting member 9 is arranged away from the fuel electrode surface 23a inside the surface side flow path 7a of the fuel gas flow path 7. Is different. Other configurations are the same as those of the first embodiment. 8 is a cross-sectional view of the single cell 2 and the separator 3 corresponding to FIG.

  The heat conducting member 9 of the present embodiment has a smaller cross-sectional area than the heat conducting member of the first embodiment. Further, the heat conducting member 9 is fixed to the separator 3. Also in the present embodiment, since a space through which the fuel gas flows is formed between the heat conducting member 9 and the fuel electrode surface 23a, the same effects as in the first embodiment are achieved.

(Other embodiments)
The present invention is not limited to the above-described embodiment, and can be appropriately modified within the scope described in the claims as follows.

  (1) In each of the embodiments described above, the heat conducting member 9 has a circular cross-sectional shape, but it may be other shapes such as a polygon instead of a circle. However, even if the cross-sectional shape is a shape other than a circle, the heat conducting member 9 is arranged in line contact with the fuel electrode surface 23a or away from the fuel electrode surface 23a.

  (2) In each of the above embodiments, the heat conducting member 9 is the same as the width of the fuel electrode 23 in the fuel gas flow direction, but may be shorter than that. That is, the heat conducting member 9 may not face the range from the one end 23c1 to the other end 23c2 in the fuel gas flow direction of the fuel electrode 23. The heat conducting member 9 only needs to extend in the fuel gas flow direction so that the temperature difference in the fuel gas flow direction of the single cell 2 can be reduced.

  (3) In each of the above embodiments, as shown in FIGS. 3 and 4, the plurality of surface-side flow paths 7 a are formed by the uneven shape of the separator 3. A plurality of surface-side flow paths 7a may be formed by these members. For example, the separator 3 is arranged in a planar shape so that a space is formed between the separator 3 and the fuel electrode surface 23a. A plurality of surface-side flow paths 7a may be formed by arranging a partition member that partitions the space between the fuel electrode surface 23a and the separator 3 into a plurality of flow paths.

  (4) In each of the above embodiments, the heat conducting member 9 is disposed inside the surface side flow path 7 a of the fuel gas flow path 7, but the heat conducting member 9 is disposed on the surface side flow path 6 a of the air flow path 6. It may be arranged only inside. Further, the heat conducting member 9 may be disposed inside both the fuel gas channel 7 and the air channel 6.

  (5) In each of the above embodiments, the present invention is applied to the fuel cell 1 in which a plurality of flat single cells are stacked. However, the present invention can also be applied to a fuel cell having only one flat single cell. Is possible.

  (6) The above embodiments are not irrelevant to each other and can be combined as appropriate unless the combination is clearly impossible. In each of the above-described embodiments, it is needless to say that elements constituting the embodiment are not necessarily essential unless explicitly stated as essential and clearly considered essential in principle. Yes.

2 Single cell 21 Electrolyte 22 Air electrode (electrode)
23 Fuel electrode (electrode)
23a Fuel electrode surface (electrode surface)
3 Separator (channel forming member)
7 Fuel gas flow path 9 Heat conduction member

Claims (4)

A plate-shaped electrolyte (21) composed of a solid oxide and having a main surface;
Flat electrodes (22, 23) provided on the main surfaces (21a, 21b) of the electrolyte and having electrode surfaces (22a, 23a) on the side opposite to the electrolyte side;
A flow path forming member (3) disposed opposite to the electrode surface and forming a reactive gas flow path (6, 7) between the electrode surface and a reactive gas flowing parallel to the electrode surface;
A heat conducting member (9) disposed between the electrode surface and the flow path forming member and having a higher effective thermal conductivity per unit cross-sectional area than the electrode and the flow path forming member;
The fuel cell according to claim 1, wherein the heat conducting member extends in the reaction gas flow direction and forms a space through which the reaction gas flows between the heat conduction member and the electrode surface.   2. The fuel cell according to claim 1, wherein the heat conducting member is opposed to a range from one end (23 c 1) to the other end (23 c 2) in the reaction gas flow direction of the electrode surface (23 a). .   The fuel cell according to claim 1, wherein the heat conducting member is in line contact with the electrode surface in the reaction gas flow path. The fuel cell according to claim 1, wherein the heat conducting member is separated from the electrode surface in the reaction gas flow path.

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