JPH0982344A - Fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the highest temperature in a cell, uniformize the temperature distribution, and improve the battery service life by arranging a first arrangement group whose projected area is the largest in the gas flow direction on the outlet side of fuel gas, and arranging a second arrangement group whose projected area becomes the smallest on the inlet side of the fuel gas. SOLUTION: Support materials 13 having projections 12 are arranged in fuel gas passages 9 and 10, and the projections 12 have a length in the same degree with a passage height 1.8mm, and contact with electrodes 4 and 5, and prevent a current collecting action and deformation of the electrodes and deformation of the gas passages 9 and 10. The support materials 13 are arranged in the anode side passage 9 so that side surfaces 14 of the support materials 13 face a gas flow. That is, they are arranged so that the projected area of the support materials 13 becomes the largest when viewed from the gas flow. The gas flow is disturbed by the side surface parts 14 of the support materials 13, and mixing of hydrogen of a reaction component, water of a generating component and CO2 is improved, and the hydrogen concentration on an electrode surface is improved. Next, on the cathode side, the side surface parts 14 of the support materials 13 are arranged so as to become parallel to the gas flow. A second passage constituting body is arranged in an inlet of fuel gas 7, and a first passage constituting body is arranged on the outlet side. Its area rate is 3:7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell, and more particularly to a fuel cell of a molten carbonate fuel cell having a gas flow path structure in which a fuel gas and an oxidant gas are orthogonal to each other.

[0002]

2. Description of the Related Art JP-A-63-116368 and JP-A-56-168364 are used to adjust the flow rate of gas supplied to a fuel cell. In the former invention, a large amount of fuel gas flows from the concentration side of the reaction gas to the region where the reaction is active, that is, the oxidant gas inlet side, and a small flow rate is flowed to the region where the reaction is relatively inactive, that is, the oxidant gas outlet side. In this way, it is described that the waste of fuel is eliminated, the utilization factor of fuel is made uniform in the plane, and a gas shortage region is not generated. The latter is intended to make the reaction distribution uniform by providing a flow rate distribution also on the oxidant gas side.

Japanese Laid-Open Patent Publication No. 1-63272 relates to the arrangement of ribs, which are flow passage constituent elements, provided in the gas flow passage surface. By angling the ribs with respect to the flow direction, the gas can be directed in any direction. In order to make the temperature uniform and the reaction uniform, the flow resistance is changed to reduce the pressure difference between the anode and cathode electrodes.

[0004]

[Problems to be Solved by the Invention] Japanese Patent Laid-Open No. 63-116368
In the inventions of JP-A-56-168364 and the like, making the temperature distribution uniform is not considered and it does not contribute to the reduction of the temperature difference in the cell. That is, the temperature distribution is determined by the current density distribution or the heat transfer with the surroundings and the gas flow path type (particularly the oxidant gas side). Among them, the current density distribution changes along the flow direction of the fuel gas, and it is unavoidable that the current density decreases as the hydrogen concentration decreases, so the fuel gas inlet side has a higher current density than the outlet side. Also, the heat generation density becomes higher at the entrance. In addition, there is a description that the flow rate distribution is attached to the fuel gas.

Further, as a means for providing the flow rate distribution, it is proposed to change the cross-sectional area of the flow channel by changing the flow channel width and the flow channel height.

If the width of the flow path changes in the plane, the contact area between the electrode and the partition plate may not be uniform, and the current distribution may change. In addition, changing the flow path height makes it very difficult to manufacture a flow path structure including a partition plate, which leads to an increase in cost, and it is more effective to obtain a uniform surface pressure on the electrode. It will be difficult.

If the in-plane gas flow direction is made different depending on the rib angle, the stagnation part of the gas flow, the low flow velocity,
The reaction gas shortage easily occurs due to the generation of the low flow rate region.

The present invention has been made in view of the above points, and it is possible to create a flow rate distribution while maintaining the flow path height, the contact area with the electrode, and the contact surface pressure substantially uniform in the surface, and the temperature distribution of the cell. It is an object of the present invention to provide a fuel cell capable of achieving uniform fuel cell efficiency. Another object of the invention is to achieve the fuel cell with the same flow path forming member only.

[0009]

Means for Solving the Problems The above-mentioned object is to provide an electrolyte plate,
A unit battery composed of an anode and a cathode electrode sandwiching the electrolyte plate, wherein the unit batteries are stacked with a separator interposed therebetween, and a fuel gas or an oxidant gas flows between the anode or the cathode electrode and an adjacent separator. In the fuel cell in which a gas flow path surface is formed, and a support material is interposed in the gas flow path surface, and the flow directions of the fuel gas and the oxidant gas are substantially orthogonal to each other, the fuel gas flow path surface and the oxidation are At least one of the support surfaces of the agent gas flow path is made of a plate having a projection, and the projection has a direction in which the projected area is large and a direction in which the projected area is small. And a projected area large region in which the large area is opposed, and a small projected area region in which the small projected area is opposed, the large projected area region and the small projected area region. It can be achieved by comprising separated parallel to the oxidant gas flow direction. According to the present invention, the in-plane flow rate can be adjusted without dividing the gas flow path surface by a partition plate or the like. Further, the substantial flow direction of the gas can be the same from the inlet side to the outlet side. In contrast to flowing the gas by curving the gas flow, it is possible to prevent large stagnation or concentration of the gas in the plane, so that even in a stacked fuel cell, it is easy to adjust the gas flow distribution for each cell. be able to.

Since the fuel cell of the present invention has the above-mentioned supporting material, it constitutes a predetermined gas passage, maintains the mechanical strength of the passage surface, and makes good electrical continuity between the electrode and the partition plate. In addition, sufficient contact portions can be provided on both the partition plate and the electrodes.

A projection in which the projected area of the support material is large when the arrangement of the support material having the protrusions is viewed from the gas flow direction without changing the height of the passage and the contact area per unit area with the electrodes and the partition plate. It can be characterized in that at least two large area areas and small projected area small areas are combined in a plane.

According to the present invention, the support member on at least one of the fuel gas flow path surface and the oxidant gas flow path surface is a plate having a protrusion, and the protrusion has a plate shape having a curved or bent portion, and The projections have different projected areas on the front and side surfaces, the front surface has the projected area defined by the width and height of the substantial projection, and the side surface is defined by the width and plate thickness of the substantial projection. Front projection region (also referred to as a large projection area region or a first flow channel structure body) having the above-mentioned projected area and having the above-mentioned projection on the flow channel surface so as to face the front with respect to the gas flow direction, And a side surface protrusion region (a small projected area or a second
(Also referred to as the flow path constituent body).

The projected area defined by the width and height of the substantial projection has, for example, the maximum projected area when the projection is laterally projected. The projected area defined by the width and plate thickness of the substantial protrusion has, for example, the smallest projected area when the protrusion is projected from the lateral direction.

As a result, the above object can be achieved with a simple structure.

Further, the front projection area and the side projection area of the oxidant gas flow path surface are divided in parallel to the flow direction of the oxidant gas.

According to the present invention, the gas flows are substantially in the same direction, and the gas flow path plane does not have a curved gas flow path. Further, the reaction within the gas flow channel surface can be made uniform.

Further, the side projection region is arranged on the inlet side of the fuel gas. It is possible to arrange the side surface protruding region from the center of the cell toward the fuel gas inlet side from the oxidant gas inlet to the outlet, and arrange the front side protruding region in the remaining portion. This is particularly effective when a heat spot is likely to be formed near the fuel gas inlet side.

Further, the fuel gas flow channel surface is formed by the front projection region, and the oxidant gas flow channel surface is formed by dividing the front projection region and the side projection region in parallel to the oxidant gas flow direction. The protrusion region is arranged on the fuel gas inlet side.

Basically, when the reaction gas (fuel gas) is provided with a flow rate distribution, the reaction amount, that is, the current, increases more in a region where a large flow amount flows, and conversely, the reaction amount decreases more in a low flow amount region. As a result, the current density distribution becomes large and the cell performance deteriorates. In particular, since the fuel side generally has a smaller flow rate and a higher utilization rate than the oxidant side, the effect of non-uniformity of the flow rate distribution on the deterioration of cell performance becomes more remarkable. The present invention can avoid the above inconvenience by controlling the flow path of the oxidizing gas.

Further, the protrusion is deformable in the vertical direction of the protrusion. Good in-plane contact,
Even in the case of a battery configuration in which the electrode plate and the supporting material are in direct contact with each other, stress concentration on the electrode plate can be relaxed and a good battery can be obtained.

Further, the fuel gas passage surface is characterized in that the side surface protruding region is arranged in a region where the temperature becomes highest when it is constituted by only one of the protruding regions. For example, when the gas flow rate in the gas flow path surface is not changed, the side projection area is a portion where a heat spot can be formed, whereby the area can be efficiently cooled,
It is possible to make the temperature uniform.

Specifically, the side surface protruding region is arranged in a region where the temperature becomes highest when the oxidizing gas passage surface is constituted by only one of the protruding regions, and the side surface protruding region is arranged. It is possible to have a front protrusion region on another portion of the flow path surface. For example, the combination of the arrangement of the above support materials is applied only to the oxidant gas passage side, and the passage that passes through the region with the highest temperature corresponding to the temperature distribution when the gas flows uniformly has a Proportion occupied by protrusions that are formed so that the proportion of the protrusions that are arranged to face the side is the largest, and that passages that have a lower temperature corresponding to the temperature of the passing region gradually face toward the front Is larger than the proportion of the projections arranged so as to face the side surface, and the fuel gas side can be configured by a front projection region composed of the projections arranged so as to face the front surface.

The protrusions applicable to the present invention can be formed in a shape as shown in FIG. 10, for example. For example, the shape as shown in FIG. In addition, as shown in (b), C type (semicircular type), S (inverted S) type, bowl type (arch type),
A semi-circular shape having a partially planar shape, or another shape can be used. The arrow in the figure indicates that the material can be deformed in the arrow direction (the vertical direction of the protrusion).

In the C type (semi-circular type) and S (reverse S) type, the rigidity in the direction of the arrow can be further lowered, so that good surface contact with the electrode can be achieved. For example, the amount of compressive deformation can be 40 μm or more.

A plate having a thickness of, for example, about 0.3 to 0.4 mm can be used. Generally, stainless steel can be used. For example, oxidant gas side: SUS316, fuel gas side:
Ni clad (Ni + SUS310S + Ni) can be used. Those protrusions having low rigidity can be used.
Thereby, good contact with the electrodes can be achieved.
The amount of compressive deformation is preferably 40 μm or more. For example, the amount of compressive deformation is preferably about 40 μm at 3 kg / cm ² or more.

[0026]

According to the present invention, a clear flow rate difference can be arbitrarily established in each flow path while efficiently flowing a gas to each unit cell of a laminated battery. Make the distribution of surface pressure uniform,
The in-plane gas flow rate difference can be set arbitrarily.

Further, since the support material having the protrusions of substantially the same shape is dispersed almost uniformly in the flow path surface, the rigidity of the support material can be made uniform in the surface, and the contact surface pressure with the electrode etc. Can be made uniform. Therefore, the contact resistance can be made uniform, and uniform current collection can be achieved, so that current concentration in the plane can be suppressed. Further, in order to adjust the gas flow rate in the gas flow passage surface by the flow passage width and depth, it is necessary to change a considerable width and the like, but in the present invention, current concentration and separator rigidity due to a large change in width and the like. There is a risk of unevenness,
A good battery can be obtained without the contact surface pressure becoming uneven.

Further, in the present invention, the gas flow direction is substantially the same on the gas inlet side and the gas outlet side of the gas flow path surface, so that a large low flow velocity is obtained as in the case of forming a curved flow path in the gas flow path surface. Since no part (stagnation part) is formed, it is possible to prevent performance deterioration due to concentration decrease or reaction gas shortage.

In the case of a cross flow type cell, a high temperature portion is likely to occur near the fuel gas inlet side in view of the current density distribution or heat generation density distribution, and the temperature decreases toward the fuel gas outlet side. Therefore, by providing a second flow path structure having a small projected area, that is, a low flow path resistance, in the oxidant gas passage that will pass through the high temperature portion, a larger amount of gas flows therethrough, The cooling effect of the cell temperature becomes high, and the maximum temperature becomes low. On the contrary, since the first flow path structure having a large flow path resistance is arranged in the vicinity of the oxidant gas outlet side where the temperature becomes low, the amount of passing gas becomes small and the temperature decrease can be prevented. As a result, the maximum temperature decreases and the minimum temperature increases, and the in-plane temperature difference decreases. Further, in order to make the temperature uniform, a considerably large flow rate difference is required. Therefore, the optimal flow channel structure for increasing the flow channel resistance difference is that the projected area of the flow channel constituent support material when viewed from the gas flow direction is It is necessary to make a big difference, and by using the support material made of the thin plate of the present invention, it is only necessary to change the arrangement direction and the width of the protrusion of the support material, and from very small to large area. It can be easily formed.

According to the present invention, the same flow path constituent member is used to keep the flow path height, the contact area with the electrode and the contact surface pressure uniform in the surface, and the gas flow direction in the surface is substantially the same. It is possible to provide a fuel cell which is in the same direction, can generate an arbitrary flow rate distribution without forming a stagnation portion in the surface, and can make the temperature distribution of the cells uniform.

[0031]

EXAMPLES The present invention will be described below based on examples.

(Embodiment 1) FIGS. 1 to 4 show an embodiment of the present invention. In the unit cell 1 of the fuel cell shown in FIGS. 1 and 2, an internal manifold 2 for supplying a fuel gas and an internal manifold 3 for supplying an oxidant gas are used as a unit in order to supply a reaction gas to each unit cell constituting the battery. It is provided around the cell 1. The unit cell has electrode anodes 4 and cathodes 5 arranged to face each other, and an electrolyte plate 6 provided between these electrodes 4 and 5, and fuel gas 7, A space is provided for passing the oxidant gas 8. That is, the anode 4,
Gas passages 9 and 10 are provided on the opposite side of the cathode 5 from the electrolyte plate 6, and the internal manifold 2 supplies the fuel gas 7 to each gas passage 9 of the anode 4, and the internal manifold 3 supplies the oxidant gas 8 to the cathode 5. Is supplied to each gas passage 10. Further, a partition plate 11 for separating both gases is provided between both gas passages 9 and 10. In the present embodiment, the unit cell configured as described above secures the strength of both the gas passages 9 and 10 to prevent the passages from being deformed, and further transmits the current generated in the electrode to the partition plate 11 side. In order to carry out a conductive action, a supporting member 13 having a projection 12 made of a thin plate having a thickness of 0.3 mm shown in FIG. 3 is provided.

The protrusion 12 has a length of about 1.8 mm, which is the height of the passage, and is in contact with the electrode, so as to prevent current collection, deformation of the electrode, and deformation of the space of the gas passages 9 and 10.
It plays the role of a support material from the viewpoint of strength. Here, as shown in FIG. 3, the support member 13 is arranged in the anode side passage 9 so that the side surface 14 of the support member 13 faces the gas flow. That is, it is arranged so that the projected area of the support member 13 is the largest as seen from the gas flow. This is called a first flow path structure. This was taken into consideration to ensure that the fuel gas was well diffused over the entire surface of the cell, and the gas flow was disturbed by the side surface portion 14 of the support material, and the reaction component hydrogen and the product components water and carbon dioxide were mixed. Is improved and the hydrogen concentration on the electrode surface is improved.
In addition, the drift of the flow in the cell plane is reduced, the gas shortage region is eliminated, and the cell performance is improved. Next, on the cathode side, the arrangement shown in FIG. 4 is further combined with the arrangement shown in FIG. As shown in FIG. 4, the side surface portion of the support member 13 is arranged so as to be parallel to the gas flow. That is, the arrangement of FIG. 3 is rotated by 90 °. This is called a second flow path structure. Then, as shown in FIG. 1, the second flow path forming body is arranged on the inlet side of the fuel gas 7 to
The first flow path structure is disposed on the outlet side of the. In this embodiment, the area ratio occupied by the first and second flow path forming bodies is 3: 7.
And

The decisive difference between the first and second flow path components is the flow path resistance. FIG. 5 shows a comparison between the flow rate and the pressure loss when flowing through the passage. As a result, the first flow path component has a larger pressure loss and a larger flow path resistance than the second flow path component, even if the same flow rate flows. When the support material 13 of this example is applied to a battery, the ratio of the gas flow rate flowing through the first flow path forming body and the gas flow rate flowing through the second flow path forming body is 1: 3 to 1: 4.

Oxidant gas 8 entered from the manifold 3
Flow toward the outlet, but the first flow path structure and the second flow path structure
The gas flowing through the flow passage structure in the same direction is in the same direction, and the flow is only slightly disturbed at the first and second boundary portions, and since it flows almost straight, a low flow velocity region and a stagnation portion are generated in the surface. Does not occur.

FIG. 6 shows an example of the temperature distribution of a cell formed on the cathode side with a single flow path forming body as in the conventional case. The highest temperature region exists near the fuel gas inlet side. On the other hand, FIG. 7 shows an example of the temperature distribution in the case of the present embodiment of FIG. The oxidant gas passage that passes through the area where the temperature rises
By providing the first flow path component in the oxidant gas passage portion passing through the outlet side of the fuel gas 7 having a relatively low temperature, the temperature distribution in the cell is improved and the maximum temperature Reduction, the temperature difference in the cell plane is reduced.

As a result, the maximum temperature is lowered, the consumption of the electrolyte due to corrosion and the evaporation amount are suppressed, and the battery life is improved. Also, due to the smaller temperature distribution,
Thermal stress is also reduced and battery reliability is improved.

(Second Embodiment) In the second embodiment, the oxidant gas flow rate distribution in the cell is controlled more finely. As shown in FIG. 8, the oxidant gas passage side is divided into a plurality of portions from the fuel gas inlet side toward the outlet side, and the oxidant gas passage side is divided into a passage that passes through the highest temperature region corresponding to the temperature distribution in FIG. Means that only the second flow path structure is used, and the ratio of the first flow path structure increases as the temperature decreases. FIG. 9 shows the temperature distribution when the ideal flow rate distribution is formed. Table 1 shows a comparison of the temperature distribution results when the ideal flow rate distributions were realized in the conventional example, the first example, and the second example. It can be seen that the temperature distribution is further improved by Example 2.

[0039]

[Table 1]

[0040]

As described above, according to the present invention, the same flow path forming member is used, and the flow path height, the contact area with the electrode and the contact surface pressure are kept constant within the surface of the cell. The temperature distribution can be made more uniform.

[Brief description of drawings]

FIG. 1 is a transverse cross-sectional view of a cathode-side surface of an embodiment of a fuel cell of the present invention as seen from above.

FIG. 2 is a vertical sectional view of a unit cell according to an embodiment.

FIG. 3 is a bird's eye view of the support material of the present invention.

FIG. 4 is a bird's eye view of the support material of the present invention.

FIG. 5 is a view showing a flow path resistance comparison when the support materials of FIGS. 3 and 4 are used.

FIG. 6 is a diagram showing a conventional temperature distribution.

FIG. 7 is a diagram showing a temperature distribution of Example 1.

FIG. 8 is a conceptual diagram showing a support material arrangement of Example 2.

FIG. 9 is a diagram showing a temperature distribution according to the present invention.

FIG. 10 is a view showing protrusions of the support material of the present invention.

FIG. 11 is a diagram showing an example of the distribution of the support material in the oxidant gas flow channel surface of the present invention.

[Explanation of symbols]

1 ... Unit cell, 2, 3 ... Internal manifold, 4 ... Anode, 5 ... Cathode, 6 ... Electrolyte plate, 7 ... Fuel gas, 8 ...
Oxidant gas, 9 ... Anode side passage, 10 ... Cathode side passage, 11 ... Partition plate, 12 ... Projection portion, 13 ... Support material, 21
… High temperature part.

Claims (6)

[Claims] 1. A unit battery comprising an electrolyte plate, an anode and a cathode electrode sandwiching the electrolyte plate, the unit batteries being laminated with a separator interposed between the anode or cathode electrode and an adjacent separator. In a fuel cell in which a gas channel surface through which a fuel gas or an oxidant gas flows is formed, and a support material is interposed in the gas channel surface, and the flow directions of the fuel gas and the oxidant gas are substantially orthogonal to each other. The support member on at least one of the fuel gas flow channel surface and the oxidant gas flow channel surface is formed of a plate having a protrusion, and the protrusion has a plate shape having a curved or bent portion, and the protrusion has a front surface. The projected area is different from the side surface, the front surface has the projected area defined by the width and height of the substantial protrusion, and the side surface has the projected area defined by the width and the plate thickness of the substantial protrusion. Then To the gas flow direction in the serial flow path surface,
A fuel cell, comprising: a front protrusion region in which the protrusion is arranged so as to face the front face, and a side protrusion region in which the protrusion is arranged so as to face the side face. 2. The fuel cell according to claim 1, wherein the front projection region and the side projection region of the oxidant gas flow channel surface are partitioned in parallel to the flow direction of the oxidant gas. 3. The fuel cell according to claim 2, wherein the side surface protruding region is arranged on the fuel gas inlet side. 4. The fuel cell according to claim 1, wherein the fuel gas flow path surface comprises the front projection area, and the oxidant gas flow path surface has the front projection area and the side projection area parallel to the oxidant gas flow direction. The fuel cell is characterized in that the side surface protruding region is arranged on the fuel gas inlet side. 5. The fuel cell according to claim 1, wherein the protrusion is deformable in the vertical direction of the protrusion. 6. The fuel cell according to any one of claims 1 to 4, wherein the side surface protruding area is formed in the area where the temperature becomes highest when the oxidizing gas passage surface is constituted by only one of the protruding areas. A fuel cell, wherein the fuel cell is disposed and has a front protrusion region in another portion of the oxidant gas flow channel.