JPH0810603B2 - Fuel cell - Google Patents

Description

TECHNICAL FIELD The present invention relates to a fuel cell, and more particularly to a fuel cell suitable for uniforming the temperature distribution of the entire laminated cell.

[Conventional technology and problems]

A conventional fuel cell has a structure in which the gas supply direction is changed within a unit battery cell as described in JP-A-62-147664.

In the fuel cell, there are heat generation due to cell chemical reaction, heat generation due to electric ion conduction, etc. In order to operate the cell within the allowable temperature range, the temperature rise due to these heat generation must be kept within the allowable value by cooling. I won't. As the cooling method, there are a method of providing a cooling plate between the laminated batteries and a method of supplying a larger amount of oxidant gas than the flow rate required for power generation to use it as an oxidant and at the same time to use a process gas as a cooling gas. is there.

Among them, in the cooling plate method, in order to cool the whole laminated battery, the number thereof is also increased, and the battery height is increased. Further, regardless of whether it is air-cooled or liquid-cooled, there is a problem that a dedicated pipe is required and the structure becomes complicated.

In the process gas cooling system, the oxidant gas must be supplied as much as necessary to keep the flow rate of the oxidant gas within the allowable temperature range of the battery. In this case, there is a problem that not only the auxiliary power for supplying the oxidant gas increases, but also the power generation efficiency decreases.

Therefore, the conventional fuel cell described above describes a method of changing the temperature distribution in the cell by changing the flow pattern of the gas supplied to the unit cell to make the temperature distribution of the entire cell uniform. .

However, the above-mentioned conventional technology does not consider the point of uniform temperature distribution of the whole laminated battery, and the conventional wet sealing method is provided as the sealing method of the gas flow path partition in the cell. In order to achieve the sealing effect, there is a problem that the width of the partition wall becomes large and the temperature distribution of the entire cell becomes uneven.

[Problems to be Solved by the Invention]

The present invention has been made in view of the above points, and an object of the present invention is to provide a fuel cell capable of making the temperature distribution of the entire laminated cell uniform.

[Means for solving the problem]

The inventors of the present invention have different temperature distributions in the battery due to the difference in gas flow pattern in the battery. Further, by changing the flow pattern among the unit batteries, each unit battery has a different temperature distribution, and these are stacked. It was found that the temperature distribution of the entire battery can be made uniform by doing so, and as a result of further research based on this new finding,
The present invention has been completed.

The present invention relates to a fuel cell in which a unit cell including an electrolyte plate, an oxidant electrode and a fuel electrode that sandwich the electrolyte plate from both sides, and a separator plate that separates the fuel gas and the oxidant gas are stacked. The unit cell has the same direction in all unit cells, and the flow direction of the oxidant gas is the same as the flow direction of the fuel gas, and the first direction in which the flow direction of the oxidant gas is orthogonal to the flow direction of the fuel gas. And a unit cell that is a second direction in which the flow direction of the oxidant gas is orthogonal to the flow direction of the fuel gas and is opposite to the first direction. And the fuel cell.

A unit cell in which the flow direction of the oxidant gas is the same direction as the flow direction of the fuel gas, a unit cell in which the flow direction of the oxidant gas is a first direction orthogonal to the flow direction of the fuel gas, and an oxidant gas It is preferable that unit cells having a second flow direction that is orthogonal to the flow direction of the fuel gas and that is a second direction opposite to the first direction are sequentially stacked in this order.

As described above, various flow patterns are configured depending on the direction in which the oxidant gas is passed, but in order to suppress the maximum temperature to the allowable temperature or lower and to make the temperature distribution uniform, How to combine is the most important factor.

Particularly preferably, in the cathode-anode cross-flow type, when the oxidant gas is caused to flow in the direction opposite to the flow of the oxidant gas flowing through the adjacent cells, heat exchange between the high temperature portion and the low temperature portion of each cell occurs, and the cathode The temperature decrease at the inlet and the temperature increase at the cathode outlet are suppressed, and the temperature distribution becomes uniform as a whole.

In particular, when the oxidant gas also serves as a cooling medium, the oxidant gas is caused to flow in an amount larger than that required for power generation, so that the temperature distribution in the battery largely depends on the oxidant gas flow. Therefore, the present invention adopts a method of changing only the flow direction of the oxidant gas.

However, only with the method in which the oxidant gases are opposed to each other as described above, the anode inlet side of the cell central portion becomes a high temperature portion. To improve this further,
By incorporating a cathode-anode parallel flow type cell orthogonal to the oxidant gas, cooling of the high temperature portion near the anode inlet side is promoted, and the temperature distribution can be improved. However, if the ratio of this parallel type cell to the whole laminated battery is too large, the influence of the parallel flow type temperature distribution becomes strong and the temperature decrease at the cathode inlet side becomes remarkable, which is rather disadvantageous for uniform temperature distribution. Become.

As shown in the present invention, the most effective relaxation of the temperature distribution can be achieved by equally dividing the proportion of the cells having the respective flow patterns in the whole.

Therefore, in the present invention, the cathode, the anode parallel flow type and the 2
In a laminated battery having three types of flow patterns of cathode and anode cross-flow type in which the flow directions of the oxidant gases of different types are opposite to each other, each cell occupies 1/3.

[Action]

In the fuel cell of the present invention, the flow pattern of the fuel gas or the oxidant gas supplied to the individual unit cells stacked in the fuel cell is changed by changing the flow pattern between the unit cells. Generates a temperature distribution based on the flow pattern, but if the in-plane temperature distribution differs between each cell, heat transfer and heat exchange occur between the stacking directions, that is, between adjacent cells, and the temperature distribution of the entire stacked battery Is alleviated, and uniform temperature distribution can be achieved.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings. An embodiment of the present invention is shown in FIGS. As shown in FIGS. 1 and 2, at the lower end of the laminated battery 1, there is a header 2 for supplying / exhausting gas from the outside to the battery 1 or from the battery 1 to the outside. Is provided with three supply pipes 4 and three exhaust pipes 5 for the oxidant gas 3, and one supply pipe 7 and one exhaust pipe 8 for the fuel gas 6, respectively. Electrolyte plates 9 having electrodes on both sides and separator plates 10 are alternately laminated on the header 2 to form one laminated battery.

The fuel gas 6 and the oxidant gas 3 supplied from the outside flow into the plenum in the header 2, from which they flow into the internal supply manifolds 11 and 13 for each gas, and are distributed to each unit cell. Then, after the electric power is generated by the electrochemical reaction in each unit cell, the mixed gas 17 of the fuel gas and the generated gas and the remaining oxidant gas 16 flow into the internal discharge manifolds 12 and 14 again, and then inside the header 2. Exhaust pipe 8 after entering the plenum
And 5 flow out of the battery. Manifold 11,12,13,1
Gas leakage from the cell 4 to the outside of the cell and mutual leakage of the fuel gas 6 with the oxidant gas 3 are caused by the sealing surface 15 of the separator plate 10.
Is prevented by a wet seal between the electrolyte plate 9 and the electrolyte plate 9, and the surface pressure of the entire battery is 2 to secure the sealing effect.
It is tightened at 5 kg / cm ² .

The gas flow pattern of this embodiment of the fuel cell thus constructed will be described with reference to FIG. FIG. 2 shows only the header 2 and the stacked battery separator 10 above the header 2. As shown in the figure, in the upper part of the header 2, only the gas passing through the internal supply manifold 11A out of the oxidant gas 3 flows in the direction of the arrow and flows out from the internal discharge manifold 12A. Note that the fuel gas flows on the back surface of the separator, flows in the direction of the arrow indicated by the broken line in the figure, and all the cells of the laminated battery are in the same direction. Therefore, in the first cell, the gas flows of the oxidant gas 3 and the fuel gas 6 are substantially orthogonal to each other.

Next, the oxidant gas 3 flowing on the front side of the first separator above the header 2 flows in through the internal supply manifold 11B, and flows in the direction of the arrow in the figure, that is, the oxidant flowing above the header 2 above. The fuel gas flows in a direction orthogonal to the gas 3, and the fuel gas flowing in the back surface of the separator 1 flows in a parallel direction. Then, it is discharged to the outside of the battery through the internal discharging manifold 12B.

Next, the oxidant gas 3 flowing on the front side of the second separator laminated on one of the first separators flows in through the internal supply manifold 11C, and flows in the direction of the arrow in the figure, that is, the first separator described above. The oxidant gas 3 that has flowed through the separator 2 also flows in a direction orthogonal to the oxidant gas 3 and also flows perpendicular to the fuel gas that flows on the back surface of the separator 2. Further, the gas flow of the oxidant gas 3 of the third separator laminated thereon returns to the same flow as the flow of the oxidant gas 3 flowing through the header 2, and the flow of the oxidant gas 3 of the previous second separator is changed. Is in the opposite direction. After that, in the gas flow of the cells to be stacked, the unit batteries having three types of flow patterns are sequentially stacked in the order described above.

In this way, the flow of the oxidant gas 3 is changed to the header 2
By combining flow patterns that are orthogonal to each other between cells as seen in the first and second separators and flow patterns in which the flows of the oxidant gas 3 are opposite to each other as seen in the above second and third separators, It is possible to obtain a fuel cell that can make the temperature distribution of the entire laminated cell uniform. The temperature distribution inside the separator will be described below.

FIG. 3 shows a conventional fuel cell in which an oxidant gas and a fuel gas flow in one direction and are orthogonal to each other. As shown in the figure, the oxidant gas 3 and fuel gas 6 are supplied from the upper and lower headers 2A, 2
It flows in from one direction through 4, 7 and flows in the battery, and then flows out of the battery through discharge pipes 5, 8. FIG. 4 shows the temperature distribution of the cross flow type gas flow pattern similar to the above second and third separators. This figure is the result of temperature distribution analysis of the separator plate. As shown in the figure, a high temperature portion is generated on the fuel gas inlet side and the oxidant gas outlet side. Similarly, FIG. 5 shows a temperature distribution analysis result in the case of a laminated battery having a flow pattern in which the oxidant gas and the fuel gas are made to flow in parallel in the same direction as shown in the first separator. In the case of parallel flow, the temperature at the inlet side of both gases is low,
The temperature is highest on the exit side.

FIG. 6 shows the result of similar temperature distribution analysis performed on the embodiment of the present invention in which the above flow patterns are combined. By combining cells with three types of flow patterns, where the positions of the high temperature part and the low temperature part are different, the position of the high temperature part is slightly behind the center of the cell, that is, the only place where there is no oxidant gas supply part. It exists near the anode outlet side, and it can be seen from these temperature distributions that the mutual temperature difference becomes small due to heat exchange between the adjacent unit cells in the stacking direction. By comparison, the maximum temperature difference in the plane is 150 ° C or higher for the cross flow type as shown in Fig. 4 and 100 ° C for the parallel flow type as shown in Fig. 5. On the other hand, in the case of the example of the present invention, it is the smallest at about 75 ° C., which shows that the temperature distribution of the whole laminated battery is improved.

〔The invention's effect〕

As described above, since the fuel cell of the present invention has the above-described structure, the temperature distribution of the whole laminated cell becomes more uniform, and the fuel cell which can make the temperature distribution uniform can be obtained. .

Further, by adopting the configuration as described in the embodiment of the present invention, the temperature distribution of the whole laminated battery is improved to be more uniform, so that a fuel cell excellent in performance, life and reliability can be obtained. , Has an excellent effect.

[Brief description of drawings]

FIG. 1 is a perspective view showing a cell stacking state of an embodiment of the fuel cell of the present invention, FIG. 2 is a perspective view showing a gas flow of the same embodiment, and FIG. 3 is an oxidant gas and a fuel gas, respectively. FIG. 4 is a perspective view showing a stacked state of a conventional fuel cell flowing in from one direction, FIG. 4 is a unit cell temperature distribution diagram when the oxidant gas and the fuel gas are orthogonal to each other, and FIG. 5 is a oxidant gas and the fuel gas are parallel to each other. FIG. 6 is a temperature distribution diagram of a unit battery in the case of flowing in the following manner, and FIG. 1 ... laminated battery, 2 ... header, 3 ... oxidant gas,
4 ... Oxidizing gas supply pipe, 5 ... Oxidizing gas exhaust pipe, 6
…… Fuel gas, 7 …… Fuel gas supply pipe, 8 …… Fuel gas exhaust pipe, 9 …… Electrolyte plate, 10 …… Separator plate, 11,13
...... Internal supply manifold, 12,14 ...... Internal discharge manifold, 15 …… Seal surface, 16 …… Oxidizing gas, 17…
… Mixed gas

Claims (2)

[Claims] 1. A fuel cell in which a unit cell including an electrolyte plate, an oxidant electrode and a fuel electrode that sandwich the electrolyte plate from both sides, and a separator plate that separates the fuel gas and the oxidant gas are stacked. The flow direction is the same in all unit cells, and the unit cell in which the flow direction of the oxidant gas is the same as the flow direction of the fuel gas and the flow direction of the oxidant gas is orthogonal to the flow direction of the fuel gas. A unit battery in the 1 direction,
The flow direction of the oxidant gas is orthogonal to the flow direction of the fuel gas,
A fuel cell is characterized in that a unit cell having a second direction that is opposite to the first direction is laminated. 2. A unit cell in which the flow direction of the oxidant gas is the same direction as the flow direction of the fuel gas, and a unit cell in which the flow direction of the oxidant gas is a first direction orthogonal to the flow direction of the fuel gas. And unit cells having a second direction in which the flow direction of the oxidant gas is orthogonal to the flow direction of the fuel gas and which is the opposite direction to the first direction are sequentially stacked in this order. The fuel cell according to claim 1.