JP2000090943A - Fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell having high cooling efficiency and a less temperature distribution in an in-plane direction and a stacking direction even when the stacked number of unit cells increases, or even under the condition of large current discharging. SOLUTION: Regarding a fuel cell 30 with a stack of unit cells 32 having an electrode-electrolyte jointed body 34 having a pair of gas diffusing electrodes jointed to both surfaces of an electrolyte, and separators 36 and 37 for clamping the electrode-electrolyte jointed body 34 from both surfaces, a plurality of coolant flow passages 38 are formed through the unit cells 32, and the flowrate and/or flow velocity of a coolant running through a plurality of coolant flow passages 38 is controlled, thereby eliminating the temperature distribution of the unit cells 32 in an in-plane direction and/or stacking direction. More specifically, each coolant flow passage 38 is arranged so as to narrow a gap toward a high temperature part, so that much coolant flows to the high temperature part of the unit cells 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a fuel cell,
More specifically, the present invention relates to a fuel cell suitable for an in-vehicle power source, a stationary small generator, and the like.

[0002]

2. Description of the Related Art A fuel cell is a battery that continuously supplies fuel and discharges combustion products, and directly converts chemical energy of the fuel into electric energy. It has features such as low emission amount, low noise and free choice of scale. Fuel cells are classified into polymer electrolyte type, phosphoric acid type, alkali type, molten carbonate type, solid oxide type, and the like, depending on the type of electrolyte used.

[0003] A unit cell, which is a power generation unit of a fuel cell, has a structure in which gas diffusion electrodes are joined to both surfaces of an electrolyte, and both surfaces are sandwiched between separators having gas channels. The principle of power generation of a fuel cell is as follows. In a unit cell having such a structure, a gas containing hydrogen, such as a reformed gas, flows on one gas diffusion electrode (fuel electrode) side, and flows on the other gas diffusion electrode (air electrode) side. Water is generated from hydrogen and oxygen by flowing a gas containing oxygen such as air, and the change in free energy at that time is directly taken out as electrical energy from separators arranged at both ends of the cell.

By the way, the electromotive force of such a cell is 1
V, and cannot be put to practical use as it is. Therefore, in order to obtain a high output voltage, the fuel cell is usually put into practical use as a fuel cell stack in which several hundred cells are stacked in series.

Further, there is a close relationship between the output of the fuel cell and the battery temperature (temperature of the electrolyte membrane), and it is necessary to maintain the battery temperature at an optimum temperature in order to obtain the maximum output. Are known.

For example, in the case of a polymer electrolyte fuel cell using a reformed gas as a fuel gas, if the cell temperature is too low,
The electrode catalyst contained in the gas diffusion electrode is poisoned by carbon monoxide in the reformed gas, and the discharge performance decreases. Further, when the battery temperature reaches a temperature equal to or higher than the boiling point of the humidified water contained in the solid polymer electrolyte membrane, the behavior of steam changes, and the discharge performance decreases.

Therefore, in a fuel cell in which a number of cells are connected in series, if the temperature of one cell deviates from the optimum temperature and the output decreases, the output of the entire fuel cell decreases. Therefore, in order to obtain the maximum output, a fuel cell is usually provided with a cooling device to maintain each unit cell at an optimum temperature.

As a cooling method for maintaining each cell at an optimum temperature, a cooling surface is provided in parallel with a fuel / oxidant passage every time several cells are stacked, and the electrolyte membrane is cooled via a separator. (Hereinafter referred to as “in-plane cooling”) and a method of providing a coolant flow path through the cell and directly cooling the electrolyte membrane through the coolant flow path (hereinafter referred to as “penetration cooling”). ) Is known (JP-A-61-131).
No. 370).

FIG. 11A shows an example of a fuel cell using in-plane cooling. The fuel cell 10 shown in FIG. 11A has a unit cell 12 in which an electrode-electrolyte assembly 14 in which a pair of gas diffusion electrodes is joined to both surfaces of an electrolyte membrane is sandwiched between separators 16, 16. It has a structure in which a cooling plate 18 is arranged every time a plurality of layers are stacked. The refrigerant flows in the cooling plate 18 in parallel with the unit cells 12.

However, as shown in FIG. 11A, in the fuel cell 10 by in-plane cooling, since the electrode / electrolyte assembly 14 is indirectly cooled via the separator 16, the thermal conductivity of the separator If the temperature is low, high cooling efficiency cannot be expected.

Further, since the cooling plate 18 is disposed every time several cells 12 are stacked, cooling of the electrolyte membrane at a position away from the cooling plate 18 becomes insufficient. Therefore, there is a problem that the temperature distribution in the stacking direction becomes large.

When the reactant gas is supplied in a so-called cross-flow manner, in which the fuel gas and the oxidizing gas are supplied at right angles, as shown in the right side view of FIG. Becomes a high temperature portion, and a temperature distribution occurs in the in-plane direction of the unit cell 12. In particular, under the condition of discharging at a high current, there is a problem that the temperature rises because relatively many reactions occur near the inlet of the reaction gas, and the temperature distribution in the in-plane direction expands.

In order to solve such a problem, a penetration cooling method has been developed (Japanese Patent Laid-Open No. 61-131370). FIG. 12A shows an example of a fuel cell using through cooling. The fuel cell 20 shown in FIG.
Cell 2 in which electrolyte joined body 24 is sandwiched between separators 26
2 are stacked in series, and a plurality of refrigerant channels 28, 28,... Vertically penetrating all the cells 22 are provided. Each of the coolant channels 28 has the same cross-sectional area and is evenly arranged in the plane of the unit cell 22. Also,
The coolant flows in the coolant channel 28 perpendicularly to the unit cells 22.

As shown in FIG. 12 (a), in the fuel cell 20 by the through cooling, the electrolyte membrane is directly cooled by the coolant passage 28 penetrating through the unit cell 22, so that high cooling efficiency can be expected. . Further, since all the electrolyte membranes are directly cooled by the coolant channel 28, there is an advantage that the temperature distribution in the stacking direction is smaller than that in the in-plane cooling.

[0015]

However, in the through-cooling, since the refrigerant passes through all the stacked cells 22, when the number of stacked cells 22 increases, the coolant near the entrance of the coolant channel 28 increases. Even when the refrigerant has a sufficient cooling capacity, the temperature of the refrigerant increases near the outlet of the refrigerant flow passage 28, and the cooling capacity decreases. Therefore, particularly under conditions of high current discharge, sufficient cooling capacity cannot be obtained near the outlet of the refrigerant flow passage 28, and there is a problem that the temperature distribution near the outlet expands.

In the case of through cooling, FIG.
As shown in the figure, when the refrigerant flow paths having the same cross-sectional area are evenly arranged, the reaction gas flows in a cross-flow method,
When the electrode reaction is performed under the condition of discharging at a high current, there is a problem that the temperature near the inlet of the reaction gas becomes high and a temperature distribution occurs in the in-plane direction. For specific means for solving such a problem, see JP-A-61-113737.
No publications such as Japanese Patent Publication No. 0 are disclosed.

The problem to be solved by the present invention is that it has a high cooling efficiency and has an in-plane direction and a laminating direction even when the number of stacked cells is large or under the condition of discharging at a high current. To provide a fuel cell having a low temperature distribution.

[0018]

In order to solve the above-mentioned problems, the present invention provides an electrode-electrolyte assembly in which a pair of gas diffusion electrodes are joined to both surfaces of an electrolyte, and the electrode-electrolyte assembly is sandwiched from both sides. In a fuel cell in which unit cells provided with a separator are stacked, a plurality of refrigerant flow paths penetrating the unit cell and a temperature distribution in an in-plane direction and / or a stacking direction of the unit cell are eliminated. And a temperature distribution eliminating means for controlling the flow of the refrigerant in the plurality of refrigerant flow paths.

According to the fuel cell of the present invention having the above-described structure, the flow of the refrigerant in the plurality of refrigerant flow paths, for example, the flow rate and / or the flow velocity of the refrigerant flowing through each of the refrigerant flow paths is determined by using the temperature distribution eliminating means. Since the control is performed, more refrigerant can flow in the refrigerant flow path arranged in the high temperature part than in the refrigerant flow path arranged in the low temperature part.

Further, when a means for increasing the cross-sectional area of the refrigerant flow path in the high-temperature portion or reducing the space between the refrigerant flow paths is used as the temperature distribution eliminating means, the reaction area in the high-temperature portion becomes small. In addition, the amount of heat generated in the high temperature section is suppressed.

Thus, even when the number of stacked cells is increased or when a high current is discharged, the temperature distribution in the in-plane direction and / or the temperature distribution in the stacked direction of each cell is reduced. be able to.

Here, the temperature distribution eliminating means includes:
It is preferable to use means for changing the cross-sectional areas and / or intervals of the plurality of refrigerant flow paths so that the ratio of the cross-sectional area of the refrigerant flow path to the area of the electrode-electrolyte assembly increases in the high-temperature portion. At the same time, the reaction area of the electrode may be reduced in the high temperature section.

When the cross-sectional area of the refrigerant flow path disposed in the high temperature section is increased or the interval between the refrigerant flow paths is reduced, the total flow rate of the refrigerant flowing through the refrigerant flow path disposed in the high temperature section is increased. , The cooling capacity can be increased. Therefore, even when discharging at a high current or when the number of stacked cells increases, the temperature distribution in the in-plane direction and the stacking direction can be reduced.

[0024] The temperature distribution eliminating means may be arranged such that the refrigerant discharged from the plurality of refrigerant flow paths arranged in the low-temperature part is a refrigerant flow path arranged in the high-temperature part and is disposed in the low-temperature part. Means for recirculating the refrigerant to a smaller number of refrigerant flow paths than the number of refrigerant flow paths may be used.

[0025] A large amount of refrigerant discharged from the plurality of refrigerant channels arranged in the low-temperature section is reduced by a number smaller than the number of refrigerant channels arranged in the high-temperature section and arranged in the low-temperature section. When the refrigerant is returned to the refrigerant flow path, the flow velocity of the refrigerant flowing through the refrigerant flow path arranged in the high-temperature portion can be increased. Therefore, even when the cooling capacity in the high-temperature portion increases and discharge is performed at a high current, or when the number of stacked unit cells increases, the temperature distribution in the in-plane direction and the stacking direction can be reduced.

Further, the temperature distribution eliminating means may be a flow path changing means for exchanging the refrigerant flowing in the refrigerant flow path arranged in the high temperature part and the refrigerant flowing in the refrigerant flow path arranged in the low temperature part. .

If the refrigerant flowing through the refrigerant flow path arranged in the high-temperature part and the refrigerant flowing through the refrigerant flow path arranged in the low-temperature part are exchanged on the way, the refrigerant having a relatively low temperature is placed in the high-temperature part. The refrigerant having a relatively high temperature flows in the low-temperature portion. Therefore, it is possible to maintain a high cooling capacity in the high-temperature portion, and to reduce the temperature distribution in the in-plane direction and the stacking direction even when discharging with a high current or when the number of stacked cells is increased. be able to.

Further, the temperature distribution eliminating means may flow the refrigerant in different refrigerant flow paths in a counter flow. By causing the refrigerant to flow through the different refrigerant channels in a counter flow, the temperature distribution in the stacking direction can be reduced as compared with the case where the refrigerant flows through all the refrigerant channels in the same direction.

[0029]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a first embodiment of the present invention.
FIG. 1 is a schematic configuration diagram of a fuel cell according to an embodiment. In FIG. 1A, the fuel cell 30 includes a unit cell 32 and a refrigerant channel 38.

The cell 32 has an electrode in which a pair of gas diffusion electrodes (not shown) are joined to both surfaces of an electrolyte (not shown).
The electrolyte joined body 34 is sandwiched between separators 36 and 37 having gas passages 36a and 37a, and the cells 32 are stacked in series. The electrode / electrolyte assembly 34 and the separators 36 and 37 are each provided with a coolant channel 38. Further, the refrigerant channel 38 is
It is formed of a material having good electrical insulation, corrosion resistance, heat resistance, and gas sealing properties.

The coolant channel 38 vertically penetrates each unit cell 32 and allows a coolant such as water or an inert gas to flow therein. Further, in the fuel cell 30 illustrated in FIG. 1, a total of 16 refrigerant channels 38 having the same cross-sectional area are arranged in a lattice shape, and each of the refrigerant channels 38 has a large cooling capacity in a high-temperature portion. It is arranged so that the interval becomes narrower as it goes to the high temperature part.

That is, as shown in the perspective view of FIG. 1A, a so-called cross-flow reaction is performed in which an oxidizing agent such as air flows from the front to the back and a fuel gas flows from the upper surface to the lower surface. When flowing gas, as shown in the right side view of FIG.

For this reason, in this embodiment, FIG.
When the as shown in the right side view, and a _1, a ₂ and a ₃ a lateral spacing of the respective refrigerant passage 38 from left to right,
Each refrigerant flow path 38 is arranged so that a ₁ <a ₂ <a ₃ . Similarly, when _b 1, _{b 2} and _{b 3} a longitudinal spacing of each of the refrigerant flow passage 38 from top to bottom, each of the refrigerant flow paths _38, b _{1 <b} 2 so that _{<b 3} Are located.

[0034] Incidentally, the refrigerant passage _38, a i _{= b} i (i
= 1, 2, 3) and a way may be arranged symmetrically, or the distance a _i in the lateral direction, the longitudinal spacing b _i may be disposed asymmetrically to be different.

Specifically, the separators 36 and 37 are used.
As shown in FIG. 2, grooves (gas passages) 36a, 37
a and a separator having peaks 36b and 37b are used.
In this case, the interval between the adjacent peaks 36b and 37b is set from the left.
A to the right₁, A₂And a ₃Yamabe 3
It is preferable to use one in which the interval between 6b and 37b is adjusted.

When the peaks 36b and 37b are arranged in this manner, the separator 3 is arranged so that the grooves 36a and 37a are orthogonal to each other.
A coolant channel 38 can be provided at a position where the ridge 36b of the separator 36 and the ridge 37b of the separator 37 cross each other when the layers 6 and 37 overlap. for that reason,
There is an advantage that the coolant channel 38 can be provided without obstructing the flow of the reaction gas.

Further, as shown in FIG. 4, a refrigerant inlet 39a is provided in a high temperature part near the upper left at the inlet side of the refrigerant flow path 38 of the stacked fuel cells 30, and more refrigerant is supplied to the high temperature part. It is preferable to arrange a flow distributor 39 in which a threshold plate for supplying is provided. When the flow distributor 39 having such a configuration is used, a large amount of the refrigerant is distributed to the high-temperature portion, and therefore, there is an advantage that the refrigerant can flow through each of the refrigerant flow paths 38 at a uniform flow rate.

Next, the fuel cell 3 having the structure shown in FIG.
The operation of 0 will be described. An oxidant is passed through a gas passage 36a provided in one separator 36 of the fuel cell 30,
When the fuel gas flows through the gas passage 37b provided in the other separator 37, the electrode reaction proceeds to generate electric power, and at the same time, the inefficiency is changed to heat and heat is generated.

At this time, since a relatively large amount of reaction proceeds near the inlet of the reaction gas, the temperature tends to rise, and a temperature distribution occurs in the in-plane direction. However, in the fuel cell 30 according to the present invention, the refrigerant flow path 38
The closer the temperature is to the high temperature part, the more densely arranged the refrigerant is. Therefore, the total flow rate of the refrigerant flowing in the high temperature part increases, and the cooling capacity in the high temperature part increases.

Therefore, the temperature distribution in the in-plane direction can be reduced even during high load operation such as low air flow and high current discharge. Moreover, the coolant passage 38 penetrating the electrolyte
As a result, all the electrolytes are directly cooled, so that a higher cooling efficiency is obtained and the temperature distribution in the laminating direction is smaller than in-plane cooling.

Further, since the refrigerant flow paths 38 are densely arranged in the high temperature section, the reaction area in the high temperature section is reduced. Therefore, the amount of heat generated near the inlet of the reaction gas is suppressed, and the temperature distribution in the in-plane direction can be further reduced.

In the conventional through-cooling in which the coolant flow paths are evenly arranged, the coolant flow paths 38 penetrating all the cells 32 are provided.
When the refrigerant flows from one side to the other, the temperature of the refrigerant is low near the entrance of the refrigerant flow path 38, and even when the refrigerant has a sufficient cooling capacity, the temperature of the refrigerant increases near the exit, Cooling capacity decreases. This decrease in cooling capacity near the outlet is caused by an increase in the number of stacked cells 32.
It becomes remarkable.

However, in this embodiment, since a large amount of refrigerant is supplied to the high-temperature portion, the unit cells 3
Even if the number of stacked layers 2 increases, the temperature rise of the refrigerant near the outlet of the refrigerant channel 38 is suppressed, and the cooling capacity can be maintained high. Therefore, the temperature distribution in the in-plane direction near the outlet can be reduced as compared with the case where the coolant channels 38 having the same cross-sectional area are evenly arranged.

Further, a flow distributor 39 as shown in FIG.
Is used, the flow rate of the refrigerant flowing through each of the refrigerant flow paths 38 can be made constant, so that a large amount of refrigerant can reliably flow through the refrigerant flow path 38 disposed in the high-temperature portion, The temperature distribution in the stacking direction can be reduced.

Next, a fuel cell according to a second embodiment of the present invention will be described. The fuel cell 4 shown in FIG.
0 indicates that the electrode-electrolyte assembly 44 is
Cell 4 sandwiched between separators 46 and 47 provided with
2, the point that the unit cells 42 are stacked in series, and the point that a plurality of refrigerant channels 48 penetrating the unit cells 42 are provided are the same as the fuel cell 30 illustrated in FIG. 1. However, the difference is that the refrigerant flow paths 48 are arranged at equal intervals, the cross-sectional area of each refrigerant flow path 48 is not the same, and the cross-sectional area of the refrigerant flow path 48 increases as the temperature becomes closer to the high-temperature portion. .

That is, as shown in FIG.
The refrigerant channels 48 are arranged in a grid pattern at equal intervals in the plane of the unit cell 42. The most upper left corner to the deployed diameter d ₁ of the refrigerant passage 48a to become a high temperature, which is the maximum within a range in which a flow path for gas to flow can be secured, is arranged on the right side of most temperature drops refrigerant passage 48d, 48h, and 48l, as well as lower the arranged coolant channel 48m, 48n, 48p and 48q diameter _{d 4} of the
Is minimized.

The diameter d of the refrigerant channels 48b, 48e and 48f provided adjacent to the refrigerant channel 48a at the upper left corner.
₂ is smaller than the diameter _{d 1} of the coolant channel 48a. Furthermore, the refrigerant flow paths 48c and 48 provided adjacent to the right and lower refrigerant flow paths 48d and the like where the temperature is lowest.
g, 48i, 48j, and the diameter _{d 3} of 48k is less than _{d 2,} and is greater than _{d 4.}

When a reactant gas is supplied to the fuel cell 40 having such a configuration in a cross-flow manner, a relatively large amount of reaction proceeds near the inlet of the reactant gas, and a temperature distribution is generated in an in-plane direction. However, the fuel cell 4 according to the present invention
At 0, since the cross-sectional area of the refrigerant flow path 48 becomes larger as it approaches the high-temperature portion, the total flow rate of the refrigerant flowing through the high-temperature portion increases, and the heat transfer area also increases. The cooling capacity increases.

Therefore, the temperature distribution in the in-plane direction can be reduced even during high load operation such as low air flow and high current discharge. Moreover, the coolant flow path 48 penetrating the electrolyte
As a result, all the electrolytes are directly cooled, so that a higher cooling efficiency is obtained and the temperature distribution in the laminating direction is smaller than in-plane cooling.

In addition, by increasing the cross-sectional area of the refrigerant flow path 48 disposed in the high-temperature section, the heat transfer area in the high-temperature section increases, and the reaction area decreases. Therefore, the amount of heat generated near the inlet of the reaction gas is suppressed, and the temperature distribution in the in-plane direction can be further reduced.

Further, by increasing the cross-sectional area of the refrigerant flow path 48 disposed in the high-temperature section, a large amount of refrigerant is supplied to the high-temperature section, so that even if the number of stacked cells 32 increases. In addition, a rise in the temperature of the refrigerant near the outlet of the refrigerant channel 38 is suppressed, and the cooling capacity can be maintained high. Therefore, the temperature distribution in the in-plane direction near the outlet can be reduced as compared with the case where the coolant channels 38 having the same cross-sectional area are evenly arranged.

Further, the refrigerant flow path 48 disposed on the high temperature side
By increasing the cross-sectional area of the fuel cell and reducing the cross-sectional area of the refrigerant flow path 48 arranged on the low temperature side, the reaction area per cell can be maintained at the same size as the fuel cell 30 shown in FIG. Can be. Thus, the temperature distribution in the in-plane direction and the stacking direction can be reduced without sacrificing the output of the fuel cell 40.

When the flow distributor 39 as shown in FIG. 4 is used, the flow rate of the refrigerant flowing through each of the refrigerant flow paths 48 can be kept constant.
8 is similar to the fuel cell 30 shown in FIG. 1 in that a large amount of refrigerant can be reliably flowed through the fuel cell 8 and the temperature distribution in the in-plane direction can be reduced.

Next, a fuel cell according to a third embodiment of the present invention will be described. The fuel cell 50 shown in FIG.
The electrode / electrolyte assembly 54 is sandwiched between separators 56 and 57 having gas flow paths 56a and 57a to form the unit cells 52, the unit cells 52 are stacked in series, and the unit cells 52 The point that a plurality of refrigerant channels 58 penetrating through is provided is the same as the fuel cell 30 shown in FIG.
The difference lies in that the coolant channels 58 having the same cross-sectional area are arranged at equal intervals, and the coolant is U-turned from the low-temperature portion to the high-temperature portion.

That is, as shown in FIG.
The refrigerant channels 48 are arranged in a grid pattern at equal intervals in the plane of the unit cell 42, and the cross-sectional areas of the respective refrigerant channels 48 are equal. Further, the fuel cell 5 shown in FIG.
At 0, the fuel gas flows from the upper surface to the lower surface,
Since the oxidizing agent is caused to flow from the back to the front, the upper right corner is a high temperature portion as shown in the right side view of FIG.

The refrigerant flows from the left side to the right side through the six refrigerant passages 58a located in the low-temperature portion at the lower left corner. In addition, the six refrigerant flow paths 58
The refrigerant discharged from a is returned to four refrigerant flow paths 58b arranged on the diagonal line from the upper left to the lower right, and flows through the four refrigerant flow paths 58b from the right side to the left side. I have.

Similarly, four refrigerant flow paths 5 arranged diagonally
The refrigerant discharged from the refrigerant passages 8b is connected to the four refrigerant passages 58b.
The refrigerant is returned to the three refrigerant channels 58c located on the higher temperature side, and flows from the left side to the right side in the three refrigerant channels 58c.

Similarly, the refrigerant discharged from the three refrigerant channels 58c is recirculated to two refrigerant channels 58d located on the higher temperature side than the three refrigerant channels 58c. Flows from the right side surface to the left side surface in the refrigerant passage 58d.

Further, the refrigerant discharged from the two refrigerant passages 58d is recirculated to one refrigerant passage 58e located at the highest temperature side, and the one refrigerant passage 58e is moved from the left side to the right side. It flows toward the surface.

As described above, when the refrigerant is caused to flow in a U-turn from the low temperature side to the high temperature side and the number of the refrigerant flow paths 58 is sequentially reduced, the refrigerant flowing through the refrigerant flow path 58 becomes closer to the high temperature part. The flow velocity increases. Therefore, during high load operation such as low air flow, high current discharge, etc.
Even when the number of stacked layers 2 increases, the cooling capacity in the high-temperature portion can be maintained high, and the temperature distribution in the in-plane direction and the stacking direction can be reduced.

Next, a fuel cell according to a fourth embodiment of the present invention will be described. The fuel cell 60 shown in FIG.
A refrigerant flow path 64 penetrating through the cell 62 is provided, and each time three cells 62 are stacked, two flow path changing devices 6
6 are stacked.

The unit cell 62 has a structure in which an electrode-electrolyte assembly (not shown) is sandwiched between separators (not shown) provided with gas channels, similarly to the fuel cell 30 shown in FIG. Is what it is.

As shown in FIG. 7 (b), in consideration of the temperature distribution in the in-plane direction, the cell 62 extends the cooling space along the diagonal direction in the cell plane into four regions (hereinafter, referred to as four regions). Each is divided into “region a”, “region b”, “region c”, and “region d”), and each region is provided with four refrigerant channels 64.

At both ends of the fuel cell 60, flow distributors 68a and 68b are provided.
The refrigerant is distributed to each of the refrigerant flow paths 64, and the refrigerant discharged from each of the refrigerant flow paths 64 is collected by the flow distributor 64 b and collected by the fuel cell 6.
It is designed to discharge from 0.

As shown in the perspective view of FIG. 8 (a), the flow path changing device 66 is provided with a partition wall 66a in a diagonal direction, and is internally divided into four parts (hereinafter, these will be referred to as "division chamber A",
“Division room B”, “division room C” and “division room D”). As shown in the schematic diagram of FIG.
Partition 66a, and one of the partitions 66a
An opening 66b is provided in the lower part of.

Each of the divided chambers is vertically divided by a triangular guide plate 66c provided in an oblique direction, and the refrigerant flowing into the upper part of each divided chamber is guided to the opening 66b along the guide plate 66c. Is discharged to the lower part of the adjacent divided chamber. That is, the flow path changing device 66 has a function of rotating the flowing direction of the refrigerant by 90 °.

The material of the flow path changing device 66 is desirably a material having good conductivity. This is because, if a material having good conductivity is used as the material of the flow path changing device 66, it can be connected in series with the unit cell 62, and the structure of the fuel cell 60 is simplified.

Further, a plurality of protrusions may be provided on the guide plate 66c in order to secure electrical conduction in the stacking direction. Furthermore, the contact area between the flow path changing device 66 and the cell 62 is:
In order to ensure electrical continuity, it is desirable that the distance be as large as possible.

Next, the operation of the fuel cell 60 shown in FIG. 7 will be described. In the case of the present embodiment, each time three unit cells 62 are stacked, the two flow path changing devices 66, 66 are stacked. The refrigerant discharged from the refrigerant flow path 64 provided in the battery 62 has its flow direction rotated by 180 ° by the flow path changing devices 66, 66, and the flow direction changing device 66,
The refrigerant flows into the refrigerant channel 64 provided in the unit cell 62 located downstream of the cell 66.

For example, as shown in FIG. 8 (b), the refrigerant discharged from the refrigerant flow path 64 disposed in the area a of the unit cell 62 located on the upstream side of the flow path changing device 66 It flows into the upper part of the division chamber A of the flow path changing device 66. The refrigerant flowing into the upper part of the divided room A is guided to the lower part of the divided room B along the guide plate 66c provided in the divided room A.

The refrigerant discharged from the lower part of the division chamber B of the first-stage flow path changing device 66 flows into the upper part of the division chamber B of the second-stage flow path changing device 66. The refrigerant that has flowed into the upper part of the divided room B is further supplied to the guide plate 66 provided in the divided room B.
Along the line c, the refrigerant is guided to the lower part of the divided chamber C and flows into the refrigerant flow path 64 arranged in the area c of the unit cell 62 located on the downstream side of the flow path changing device 66.

The same applies to the refrigerant flowing through the refrigerant flow paths 64 arranged in the areas b, c and d of the unit cell 62 located on the upstream side of the flow path changing device 66.
66, the flow direction is rotated by 180 °, and each of the cells 62 located downstream of the flow path changing device 66
Refrigerant passage 64 arranged in the region d, the region a and the region b
Flow into

Therefore, as shown in the right side view of FIG. 7 (b), when the reactant gas is flowed by the cross flow method, the regions a and d become the high temperature parts, and the regions b and c become the low temperature parts. However, by allowing the refrigerant to pass through the flow path change devices 66, 66, the refrigerant initially flowing through the refrigerant flow path 64 disposed in the high-temperature part flows through the refrigerant flow path 64 disposed in the low-temperature part. In other words, conversely, the refrigerant initially flowing in the refrigerant flow path 64 disposed in the low-temperature part flows through the refrigerant flow path 64 disposed in the high-temperature part.

As described above, if the refrigerant flowing through the low-temperature part and the refrigerant flowing through the high-temperature part are exchanged during the passage of the refrigerant through the fuel cell 60, the refrigerant having a relatively high temperature is added to the low-temperature part. Flows, and a relatively low-temperature refrigerant flows through the high-temperature portion. Therefore, the cooling capacity of the refrigerant flowing through the refrigerant flow path 64 disposed in the high-temperature portion can be maintained high, and the temperature distribution in the in-plane direction and the stacking direction can be reduced as compared with the case where the flow path changing device 66 is not provided. Can be smaller.

It is to be noted that the flow direction of the reactant gas supplied to the stacked unit cells 62 is changed by using the flow path changing device 66 instead of replacing the refrigerant flowing through the refrigerant flow path 64, whereby the flow path is changed. The same effect as when the changing device 66 is used can be obtained.

That is, as shown in FIG.
Are stacked in series to form a fuel cell 70, and each cell 72 is divided into several blocks. FIG. 9 (a)
In the fuel cell 70 exemplified in (1), three single cells 72 are stacked to form one block, which is divided into a total of three blocks.

In the first block located on the inlet side of the refrigerant passage 74, as shown in the right side view of FIG. 9B, the fuel gas flows from the upper surface to the lower surface, and the oxidant flows in the front surface. From the back to the back. Thereby, the first
In the block, the area a and the area d become high temperature parts, and the area b and the area c become low temperature parts.

In the second block located in the middle,
As shown in the right side view of FIG. 9C, the gas flow direction is reversed from that of the first block so that the fuel gas flows from the lower surface to the upper surface and the oxidant flows from the back surface to the front surface. Thereby, in the second block, the area b and the area c
Is a high-temperature portion, and regions a and d are low-temperature portions. That is, by reversing the gas flow direction in the middle, the high temperature part and the low temperature part are rotated by 180 °.

Further, the third flow path at the outlet side of the refrigerant flow path 78
In the block, the gas flow direction is reversed again, and FIG.
As shown in (b), the fuel gas flows from the upper surface to the lower surface, and the oxidant flows from the front to the rear.
As a result, in the third block, the regions a and d become high-temperature portions, and the regions b and c become low-temperature portions.

As described above, instead of using the flow path changing device to exchange the refrigerant flowing in the high temperature section and the refrigerant flowing in the low temperature section, the gas flow direction is reversed halfway, so that the refrigerant flows through the refrigerant flow path 74. The refrigerant flows between the high temperature part and the low temperature part alternately. Therefore, the refrigerant flow path 74 arranged in the high temperature section
The cooling capacity of the refrigerant flowing through the battery can be maintained high, and the temperature distribution in the in-plane direction and the stacking direction can be reduced even under high load operation or when the number of stacked cells 72 is increased. it can.

Next, a fuel cell according to a fifth embodiment of the present invention will be described. The fuel cell 80 shown in FIG.
Is used to connect the electrode-electrolyte assembly 84 to the gas flow paths 86a, 87
a between the separators 86 and 87 provided with
That each cell 82 is stacked in series,
The point that a plurality of refrigerant channels 88 penetrating each unit cell 82 are provided and that the refrigerant channels 88 having the same cross-sectional area are arranged at equal intervals are the same as the fuel cell 50 shown in FIG. However, the difference lies in that the coolant channel 88 is divided into two groups and the coolant flows so as to have a counter flow.

That is, as shown in the right side view of FIG. 10B, the sixteen coolant channels 88 are arranged in a grid at equal intervals in the plane of the unit cell 82, and each coolant channel 88 8
8 have the same cross-sectional area. In the fuel cell 80 shown in FIG. 10A, the fuel gas flows from the upper surface to the lower surface, and the oxidant flows from the front to the rear.

Each of the refrigerant flow paths 88 is formed by a first group (FIG. 10B) through which the refrigerant flows from the right side to the left side.
And a second group (indicated by “•” in FIG. 10 (b)) through which the refrigerant flows from the left side to the right side, and refrigerant flow paths belonging to the first group. 88a
The refrigerant flow paths 88a and the refrigerant flow paths 88a so that the refrigerant flow paths 88b belonging to the second group do not adjoin each other.
b are alternately arranged.

As described above, when the refrigerant flow paths 88 are divided into two groups and the refrigerant flows in such a manner as to have a counterflow with each other, the cooling capacity of the refrigerant flowing through the refrigerant flow paths 88a belonging to the first group is reduced by the fuel cell. Although it increases on the right side of the fuel cell 80, the temperature of the refrigerant rises toward the left side of the fuel cell 80, and the cooling capacity decreases.

However, since the refrigerant flow channel 88b belonging to the second group allows the refrigerant to flow from the left side to the right side of the fuel cell 80, the cooling capacity of the refrigerant flowing through the refrigerant flow channel 88b is It becomes larger on the left side of 80 and can compensate for a decrease in the cooling capacity of the refrigerant flowing through the refrigerant channel 88a belonging to the first group. Therefore, the temperature distribution in the stacking direction can be reduced as compared with the conventional method in which the coolant flows in the same direction in all the coolant channels.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various modifications are possible without departing from the gist of the present invention. is there.

For example, in the above embodiments, various methods for eliminating the temperature distribution in the in-plane direction and / or the laminating direction have been described. However, these embodiments may be used alone or The above embodiments may be used in combination.

For example, by combining the first embodiment and the fifth embodiment, the refrigerant flow paths having the same cross-sectional area are arranged so that the distance between them becomes narrower as approaching the high-temperature part. Make sure that the refrigerant channels are not adjacent to each other.
The refrigerant may be divided into two groups and the refrigerant may be flowed so as to have a counter flow. Thereby, both the temperature distribution in the in-plane direction and the temperature distribution in the stacking direction can be reduced at the same time.

Further, by combining the second and fifth embodiments, the refrigerant flow paths are arranged at regular intervals, and the cross-sectional area of the refrigerant flow path is increased as the temperature becomes closer to the high temperature portion. The refrigerant channels may be divided into two groups so as not to be adjacent to each other, and the refrigerant may be flowed so as to have a counter flow. Even in such a combination, both the temperature distribution in the in-plane direction and the temperature distribution in the stacking direction can be reduced at the same time.

Further, in the fourth embodiment, three cells are used.
Although two flow path change devices are stacked every time cells are stacked, two flow path change devices may be stacked every time two or four or more cells are stacked.

In the above-described embodiment, the fuel cell has been described in which unit cells of 6 to 9 cells are stacked, and 16 refrigerant channels are passed through the stacked unit cells.
The illustrated number of stacked cells, the number of refrigerant flow paths, and the like are merely examples, and several hundred cells having a large area may be stacked and penetrated through 17 or more refrigerant flow paths. . Then, by appropriately controlling the flow velocity and / or flow rate of the refrigerant flowing through each refrigerant flow path, it is possible to obtain a fuel cell having a small temperature distribution in the in-plane direction and the lamination direction, as in the above embodiment.

Further, the type of the fuel cell to which the present invention is applied is not particularly limited, and a polymer electrolyte fuel cell, a phosphoric acid fuel cell, an alkaline fuel cell, a molten carbonate fuel cell , Solid oxide fuel cells, etc.
The present invention can be applied to all kinds of fuel cells, whereby the same effects as those of the above embodiment can be obtained.

[0093]

According to the present invention, a unit cell comprising an electrode / electrolyte joined body having a pair of gas diffusion electrodes joined to both sides of an electrolyte and a separator sandwiching the electrode / electrolyte joined body from both sides is laminated. The fuel cell further comprises a plurality of refrigerant flow paths penetrating the unit cell, and a temperature distribution eliminating means for controlling the flow of the refrigerant in the plurality of refrigerant flow paths, so that high cooling efficiency is obtained. This has the effect that the temperature distribution in the in-plane direction and the lamination direction can be reduced.

[0094] The temperature distribution eliminating means may have a cross-sectional area and / or a cross-sectional area of the plurality of refrigerant flow paths such that a ratio of a cross-sectional area of the refrigerant flow path to an area of the electrode-electrolyte assembly is increased in a high-temperature portion. Or, if the means for changing the interval is used, the total flow rate of the refrigerant flowing through the refrigerant flow path arranged in the high-temperature portion increases, and the reaction area in the high-temperature portion decreases, so that the temperature distribution in the in-plane direction and the stacking direction is reduced. There is an effect that it can be reduced.

Further, as the temperature distribution eliminating means, the refrigerant discharged from a plurality of refrigerant passages arranged in the low temperature section is used.
A refrigerant flow path arranged in the high-temperature portion, wherein a means for returning to a smaller number of refrigerant flow passages than the number of refrigerant flow passages arranged in the low-temperature portion is used. This has the effect of increasing the flow velocity of the refrigerant flowing through the substrate and reducing the temperature distribution in the in-plane direction and the lamination direction.

Further, if the flow distribution changing means for exchanging the refrigerant flowing in the refrigerant flow path arranged in the high temperature part and the refrigerant flowing in the refrigerant flow path arranged in the low temperature part is used as the temperature distribution eliminating means, The relatively low-temperature refrigerant flows through the refrigerant flow path disposed in the low-temperature part, and the relatively high-temperature refrigerant flows through the refrigerant flow path disposed in the low-temperature part. And the temperature distribution in the in-plane direction and the lamination direction can be reduced.

Further, when the means for flowing the refrigerant in different refrigerant flow paths by the counter flow is used as the temperature distribution eliminating means, the temperature in the stacking direction can be reduced as compared with the case where the refrigerant flows in the same direction in all the refrigerant flow paths. There is an effect that the distribution can be reduced.

As described above, according to the present invention, the temperature distribution in the in-plane direction and the stacking direction of the fuel cells in which the cells are stacked is easily eliminated, and all the cells are discharged within the optimum temperature. Therefore, the maximum output of the fuel cell can be easily and stably obtained. Therefore, if this is applied to, for example, a fuel cell system for an automobile, it contributes to higher output and higher efficiency of the automobile, etc., and is an invention which has an extremely large industrial effect.

[Brief description of the drawings]

FIG. 1A is a perspective view of a fuel cell according to a first embodiment of the present invention, and FIG. 1B is a right side view thereof.

FIG. 2 is a plan view and a front view showing an example of a separator used in the fuel cell shown in FIG.

FIG. 3 is a diagram illustrating a relationship between a gas flow direction of a reaction gas and a temperature distribution generated in an in-plane direction of a unit cell.

FIG. 4 is a front view and a right side view of a flow distributor used in the fuel cell shown in FIG. 1;

FIG. 5 (a) is a perspective view of a fuel cell according to a second embodiment of the present invention, and FIG. 5 (b) is a right side view thereof.

FIG. 6 (a) is a perspective view of a fuel cell according to a third embodiment of the present invention, and FIG. 6 (b) is a right side view thereof.

FIG. 7A is a side sectional view of a fuel cell according to a fourth embodiment of the present invention, and FIG. 7B is a right side view thereof.

FIG. 8A is a perspective view of a flow path changing device used in the fuel cell shown in FIG. 7, and FIG.
It is the schematic for demonstrating the flow of the refrigerant | coolant in the flow-path change apparatus shown to (a).

9A is a side sectional view of a fuel cell according to another embodiment of the present invention, and FIG. 9B and FIG.
(C) is a diagram illustrating a generation position of a high-temperature portion when the gas flow direction of the reaction gas is reversed.

FIG. 10 (a) is a perspective view of a fuel cell according to a fifth embodiment of the present invention, and FIG. 10 (b) is a right side view thereof.

FIG. 11 (a) is a perspective view showing a conventional fuel cell by in-plane cooling, and FIG. 11 (b) is a right side view thereof.

FIG. 12 (a) is a perspective view showing a conventional fuel cell by through cooling, and FIG. 12 (b) is a right side view thereof.

[Explanation of symbols]

 Reference Signs List 30 fuel cell 32 unit cell 34 electrode / electrolyte assembly 36, 37 separator 38 refrigerant channel

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takashi Shimantsu 41-41, Chuchu-Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture Inside Toyota Central Research Laboratory Co., Ltd. (72) Inventor Kazutaka Hiroshima Nagakute, Aichi-gun, Aichi Prefecture No. 41, Toyoda Central Research Laboratories, Machidai-Cho, Chumoku Yokomichi (72) Inventor Hiroshi Aoki Inventor Hiroshi Aoki 41, Odai-Chochu Yokomichi, Nagakute-cho, Aichi-gun, Aichi F-term (reference) 5H026 AA02 CC03 CC10 HH02 5H027 AA02 CC02 CC06

Claims (5)

[Claims] 1. A fuel cell comprising a unit cell comprising an electrode / electrolyte assembly in which a pair of gas diffusion electrodes are joined to both surfaces of an electrolyte, and a separator sandwiching the electrode / electrolyte assembly from both surfaces. A plurality of refrigerant flow paths penetrating the cell, and a temperature controlling a flow of the refrigerant in the plurality of refrigerant flow paths such that a temperature distribution in an in-plane direction and / or a stacking direction of the cell is eliminated. A fuel cell further comprising a distribution eliminating means. 2. The method according to claim 1, wherein the temperature distribution eliminating unit is configured to increase a cross-sectional area of the plurality of refrigerant flow paths and / or a cross-sectional area of the plurality of refrigerant flow paths such that a ratio of a cross-sectional area of the refrigerant flow path to an area of the electrode-electrolyte assembly increases in a high-temperature part. 2. The fuel cell according to claim 1, wherein the distance is changed. 3. The cooling device according to claim 1, wherein the temperature distribution eliminating unit is configured to transfer the refrigerant discharged from the plurality of refrigerant channels disposed in the low-temperature section to the refrigerant channel disposed in the high-temperature section and to be disposed in the low-temperature section. 2. The fuel cell according to claim 1, wherein the fuel cell is recirculated to a smaller number of refrigerant flow paths than the number of refrigerant flow paths. 4. The temperature distribution eliminating means is a flow path changing means for exchanging a refrigerant flowing in a refrigerant flow path arranged in a high temperature part and a refrigerant flowing in a refrigerant flow path arranged in a low temperature part. The fuel cell according to claim 1, wherein 5. The fuel cell according to claim 1, wherein the temperature distribution eliminating means causes the refrigerant to flow through different refrigerant channels in a counter flow.