JPH0821402B2 - Fuel cell - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a fuel cell.

[Technical Background of the Invention and Problems Thereof] In recent years, fuel cells have been reviewed as a power generation device from the viewpoint of effective use of energy, and development thereof has been activated.

In general, a fuel cell supplies oxygen as an oxidant and hydrogen as a fuel to a stacked unit cell to convert energy generated by a reaction of the fuel into electric energy.

By the way, the fuel cell is accompanied by heat generation due to the above reaction, but in order to improve the power generation efficiency of the fuel cell, it is necessary to remove the heat generation of the single cell, cool it, and maintain the entire temperature at a uniform temperature.

As a fuel cell cooling device for this purpose, for example, Japanese Patent Publication Sho 58
-33670 and JP-A-52-13638.

This is, for example, substantially the same as that shown in FIG. 5, and description will be given by taking FIG. 5 as an example. That is, the unit cells 101 stacked vertically are divided into a plurality of stages (three stages in FIG. 5) of fuel cell stacks 103a, 103b, 103c, and each of the fuel cell stacks 103a, 103b, 103c has a respective Cooling plates 105a, 105b, 105c are provided at both upper and lower ends and an intermediate portion.

Cooling plates 105a, 105 of each fuel cell stack 103a, 103b. 103c
b.105c has an inlet manifold 106 on its inlet side.
a, 106b, 106c are connected, and this inlet manifold 106a, 10
The other ends of inlet pipes 109a, 109b, 109c, one end of which is connected to the main supply pipe 107, are connected to 6b, 106c.

Further, outlet manifolds 110a, 110b, 110c are connected to the cooling plates 105a, 105b, 105c on the outlet side thereof, and one end side of the outlet manifolds 110a, 110b, 110c is the main outflow pipe.
The other ends of the outlet pipes 113a, 113b, 113c connected to 111 are connected.

The main supply pipe 107 is provided with a main flow rate adjusting valve 115, the main supply pipe 107 and the main outflow pipe 111 are connected via a pump and a heat exchanger (not shown), and a closed loop as a cooling device is configured. There is. Therefore, the cooling water as the cooling fluid supplied by the pump drive is the main flow rate adjusting valve 11
The flow rate is adjusted by 5 and the main supply pipe 107 to each inlet pipe 109a, 1
It is supplied to each cooling plate 105a, 105b, 105c via 09b, 109c and each inlet manifold 106a, 106b, 106c.

In the cooling plates 105a, 105b, 105c, the heat generated in the unit cell 101 is absorbed and boiled, forming a two-phase flow of a vapor phase and a liquid phase, each outlet manifold 110a, 110b.110c, each outlet pipe 113a, 113b. , 11
It is designed to flow out to the main outflow pipe 111 via 3c.

Here, from the main supply pipe 107 to each inlet pipe 109a, 109b, 109
The pressure Pnin of the cooling water flowing into c is given by Pnin = Poin-ρL · g · Hn (1).

Here, Poin is the pressure at the lower end of the main supply pipe, ρL is the liquid density of the cooling water, g is the acceleration of gravity, and Hn is the height from the lower end of the main supply pipe to each inlet pipe.

On the other hand, each outlet pipe 113a, 113b, 1 in the main outflow pipe 111
The pressure Pnout of the cooling water at the 13c position is determined by each outlet pipe 113a, 113
If b and 113c have the same two-phase flow, Pnout = Poout− (ρL (1-α) + ρG · α) · g · Hn
… (2) is given.

Here, Poout is the pressure at the lower end of the main outflow pipe, ρG is the vapor density of the cooling water, and α is the void ratio.

Therefore, each cooling plate of each fuel cell stack 103a, 103b, 103c
The pressure difference between the inlet and outlet of the cooling water in 105a, 105b, 105c is Pnin−Pnout = (Poin−Poout) − (ρL−ρG) · α · g · Hn ... from the above equations (1) and (2). It is given in (3). In this case, ρG << ρL, so ρ
The G term can be ignored, and the above equation (3) is expressed as Pnin, −Pnout = (Poin−Poout) −ρL · α · g · Hn.
(4)

As is clear from the above formula (4), the higher the Hn of the fuel cell stack, the smaller the pressure difference between the inlet and the outlet of the cooling plate, and the cooling to each fuel cell stack 103a, 103b, 103c. A uniform water supply flow rate cannot be maintained. Therefore, each fuel cell stack
The cooling capacity of the cooling plates in 103a, 103b, and 103c is not uniform, and there is a high possibility that the two-phase flow flow instability described later will occur, resulting in a decrease in power generation efficiency.

On the other hand, as shown in FIG.
a, 109b, 109c are provided with fixed throttles 117a, 117b, 117c, and the flow rate of cooling water supplied to each fuel cell stack 103a, 103b, 103c and each fuel cell stack 103a, 103b, 103c flow out. It is conceivable that the weight ratio (hereinafter referred to as quality) of the vapor phase flow rate in the total flow rate of the fluid is set to be substantially equal.

Here, the vapor phase flow rate is the amount that the cooling water boils and changes from the liquid phase to the vapor phase, and is approximately proportional to the amount of heat absorbed by the cooling plate from the unit cells, that is, the amount of heat generated by each fuel cell stack. Determined. Therefore, the quality of the fluid that flows out for each fuel cell stack is also determined substantially in proportion to the heat generation amount of each fuel cell stack.

Further, the fixed throttles 117a, 117b, 117c are, for example, the fuel cell stacks 103a, 1c when the fuel cell operating conditions are full load operation.
Based on the calorific value of 03b, 103c and the rated flow rate (total flow rate) of the cooling water flowing through the main supply pipe 107, the inlet pipes 109a, 109b, 10
The outlet side flow rate of 9c is set to be uniform. Then, the ratio (flow rate) of each cooling water flow rate determined by the fixed throttles 117a, 117b, 117c and the average flow rate per one fuel cell stack 103a (103b, 103c), and each cooling plate 105a. , 105b, 105c outlet piping 113a, 1
When the qualities at 13b and 113c are obtained, the results are shown by the line segment in FIG. 3 and the line segment a in FIG.

Here, when the operating condition of the fuel cell changes and the partial load operation is performed, the heat generation amount in each of the fuel cell stacks 103a, 103b, 103c also decreases. Now, when the calorific value in each fuel cell stack 103a, 103b, 103c is half that in full load operation, cooling of each fuel cell stack 103a, 103b, 103c by the rated flow of cooling water I went.
When the quality at the outlet side of each cooling plate 105a, 105b, 105c at this time is obtained, it is reduced to about 1/4 of the quality at full load operation as shown by the line segment a in FIG.

By the way, generally, in a group of pipelines in which a liquid phase fluid flowing through the pipeline causes a boiling phenomenon in the middle of the flow, when the quality is usually 1% or less and 4% or more, a unique flow of gas-liquid two-phase flow is obtained. There is a risk that an instability phenomenon may occur, the flow rate flowing in the pipeline may be sharply reduced, or may fluctuate up and down in a certain cycle, which may lower the cooling capacity and promote thermal fatigue.

Therefore, it is not preferable that the quality on the outlet side of each of the cooling plates 105a, 105b, 105c as described above greatly differs depending on the change in the operating conditions of the fuel cell.

On the other hand, the cooling water supplied to the main supply pipe 107 according to the heat generation amount of the fuel cell stacks 103a, 103b, 103c in order to suppress the above-described decrease in quality on the outlet side of the cooling plates 105a, 105b, 105c. Adjust the total flow rate of the fixed throttle 117a, 1
Since the flow rate passing through 17b, 117c is significantly different from the rated flow rate, the effect of equalizing the flow rate of the cooling water by the fixed throttles 117a, 117b, 117c is weakened, and as shown by the line segment in FIG. Causes a difference of plus or minus 15% between the fuel cell stacks 3a, 3b and 3c.

In addition, as shown by the line a in FIG.
The maximum quality on the exit side of 5a, 105b, 105c is 1.75.
%, The minimum value is 0.95%, which is a big difference. Therefore, the flow rate ratio and the quality of the cooling water become non-uniform, and in this case as well, there is a problem that the cooling capacity is lowered for the same reason as in the cooling device of FIG.

[Object of the Invention] The present invention was created in view of the above problems,
Even if the operating load condition of the fuel cell changes with respect to the total flow rate of the cooling fluid supplied, the variation in the flow rate of the cooling fluid supplied to each cooling plate and the quality change at the cooling plate outlet side are significantly suppressed. However, it is an object of the present invention to provide a fuel cell capable of maintaining a stable cooling state as a whole.

SUMMARY OF THE INVENTION In view of the conventional problems as described above, the present invention provides a fuel cell in which a cooling plate is provided at both upper and lower end portions and an intermediate portion of a stacked body formed by stacking a plurality of unit cells vertically. The stacks are provided in a plurality of upper and lower stages, and a main supply pipe for supplying a cooling liquid to each cooling plate of each fuel cell stack, and a branch from the main supply pipe corresponding to each fuel cell stack With each inlet pipe,
Each inlet manifold connected from each inlet pipe to each cooling plate of each fuel cell stack, each outlet manifold connected to each cooling plate of each fuel cell stack, and main outflow pipe for collecting the cooling plate And a respective outlet pipe connecting the respective outlet manifolds to the main outflow pipe, a flow rate of a coolant corresponding to a coolant flow rate during rated operation of the plurality of fuel cell stacks. A plurality of fixed throttles provided in each of the inlet pipes so that they are always supplied to each fuel cell stack almost equally, and a plurality of bypasses connected to the outlet pipes from the downstream side of the fixed throttles. Tubes, a plurality of flow rate detection devices that detect the flow rate of the cooling liquid supplied to the cooling plate of each fuel cell stack, and output an actual flow rate signal, and the amount of heat generated by changes in the operating conditions of each fuel cell stack. Fluctuation can be confirmed Detecting means for detecting various factors, and a plurality of converting means for setting an appropriate flow rate of the cooling liquid supplied to each fuel cell stack based on each factor output from each detecting means and outputting an appropriate flow rate signal. Device, comparing the actual flow rate signal input from each of the flow rate detection devices and the appropriate flow rate signal input from each of the conversion devices to set the flow rate of the cooling liquid supplied to each of the fuel cell stacks to an appropriate flow rate. A plurality of flow rate control devices capable of controlling the flow rate of the cooling liquid flowing through each of the bypass pipes to control the flow rate of the cooling liquid flowing through the cooling plate in each of the fuel cell stacks. The configuration is such that control is performed according to changes in the heat generation amount due to partial load operation.

[Effects of the Invention] As is apparent from the above configuration, in the present invention, a fuel cell stack in which cooling plates are provided at both upper and lower ends and an intermediate portion of a stack formed by stacking a plurality of unit cells vertically Are provided in the upper and lower stages, and each inlet pipe connected to each inlet manifold connected to the cooling plate of each fuel cell stack is branched from the main supply pipe. A fixed throttle is provided in each of the inlet pipes so that the flow rate of the cooling liquid corresponding to the flow rate of the cooling liquid during the rated operation of the plurality of fuel cell stacks is constantly and substantially supplied to the respective fuel cell stacks. I am doing it.

Therefore, the flow rate of the cooling liquid supplied from the main supply pipe to the cooling plate side of each fuel cell stack is always substantially equal. That is, the flow rate of the cooling liquid supplied to the main supply pipe may be always constant, no external control is required, and the structure is simplified accordingly.

Furthermore, in the present invention, a plurality of flow rate detection devices that detect the flow rate of the cooling liquid supplied to the cooling plate of each fuel cell stack and output an actual flow rate signal are provided, and the operating conditions of each fuel cell stack are Proper flow rate of the cooling liquid supplied to each fuel cell stack based on each factor output from each of the above-mentioned detecting means, which comprises a plurality of detecting means for detecting a factor capable of confirming the variation of the heat generation amount due to the change Is provided and a plurality of converters for outputting an appropriate flow rate signal are provided.

And, a plurality of bypass pipes that connect the downstream side of each fixed throttle provided in the inlet pipe of each fuel cell stack and the outlet pipe of each fuel cell stack are provided, and the cooling liquid flowing through each bypass pipe is provided. The flow rate is controlled by controlling the flow rate of the cooling plate supplied to each fuel cell stack to an appropriate flow rate by comparing the actual flow rate signal input from each of the flow rate detection devices and the appropriate flow rate signal input from each of the conversion devices. The flow rate of the cooling liquid flowing through the cooling plate in each fuel cell stack is controlled according to the fluctuation of the heat generation amount due to the partial load operation of each fuel cell stack. It is a configuration for controlling.

Therefore, according to the present invention, the flow rate of the cooling plates supplied from the main supply pipe to the plurality of fuel cell stacks is always substantially equal, and the cooling plates of the respective fuel cell stacks have the same flow rate. The cooling liquid is supplied at an appropriate flow rate according to the heat generation amount of the partial load operation of the body, and the excess cooling liquid flows out to the outlet pipe through the bypass pipe. Even if the heat generation amount of each fuel cell stack changes individually, the quality of each fuel cell stack and the cooling liquid flowing out to each outlet pipe through each fuel cell stack can be maintained without substantially changing. Therefore, it is possible to maintain stable cooling of the whole and to always perform efficient power generation.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows a cooling system diagram of a fuel cell, in which a plurality of fuel cell stacks 3a, 3b, 3c formed by vertically stacking a plurality of unit cells 1 are arranged in a plurality of stages (three stages in FIG. 1). Cooling plates 5a, 5b, 5c are provided at the upper and lower ends and in the middle of each of the fuel cell stacks 3a, 3b, 3c. An inlet manifold 6a, 6b, 6c is connected to each cooling plate 5a, 5b, 5c on the inlet side, and an inlet pipe 9a whose one end side is connected to the main supply pipe 7 is connected to this inlet manifold 6a, 6b, 6c. , 9b, 9c are connected to the other end side. Further, the outlet manifolds 10a, 10b, 10c are connected to the respective cooling plates 5a, 5b, 5c on the outlet side thereof, and one end side of the outlet manifolds 10a, 10b, 10c is connected to the main outflow pipe 11. The other ends of the outlet pipes 13a, 13b, 13c are connected.

The main supply pipe 7 is provided with a main flow rate adjusting valve 15 for keeping the flow rate of the cooling water supplied to the main supply pipe 7 always constant, and is connected to the main supply pipe 7 via a pump and a heat exchanger (not shown). The main outflow pipe 11 is connected to form a cooling device.

Each of the inlet pipes 9a, 9b, 9c has a fixed throttle 17a, 17b, 17c.
Is provided so that the flow rate of the cooling water supplied to each of the fuel cell stacks 3a, 3b, 3c is set to be substantially equal to the flow rate of the cooling water during the rated operation.

Each of the inlet pipes 9a, 9b, 9c has a fixed throttle 17a, 17b, 17c.
A plurality of bypass pipes 19a, 19b, 19c connected to the outlet pipes 13a, 13b, 13c from the downstream side thereof are provided. Each bypass pipe 19a, 19b, 19c has a flow rate detection device 21a, 21b, 21c.
In addition, flow rate control devices 23a, 23b, 23c are provided.

Each of the flow rate detecting devices 21a, 21b.
The actual flow rate signals La, Lb, Lc are detected based on the detection result of the actual flow rate of cooling water as a cooling fluid flowing through a, 19b, 19c. The actual flow rate of the bypass pipes 19a, 19b, 19c has a correlation with the cooling water supplied to each cooling plate 5a, 5b, 5c, and as a result, the cooling water supplied to each cooling plate 5a, 5b, 5c. The actual flow rate will be detected. This actual flow signal La, L
b and Lc are configured to be input to the respective flow rate control devices 23a, 23b and 23c.

In addition, each flow rate control device 23a, 23b, 23c, the converter 25
The proper flow rate signals Sa, Sb, Sc output from a, 25b, 25c are input.

The conversion device 25a, 25b, 25c is a factor capable of confirming the fluctuation of the heat generation amount due to the change of the operating condition of the fuel cell, for example, a detection means for detecting the power generation amount of each fuel cell stack 3a, 3b, 3c.
The detection signals Ha, Hb, and Hc output from 27a, 27b, and 27c are input. The converters 25a, 25b, 25c use the detection signals Ha, Hb, Hc to detect the bypass pipes 19a, 19b, 19c.
The proper flow rate of the cooling water flowing to c, in other words, each cooling plate 5a,
It is configured to set an appropriate flow rate of the cooling water supplied to 5b, 5c and output appropriate flow rate signals Sa, Sb, Sc. This proper flow rate is determined so that the quality on the outlet side of each cooling plate 5a, 5b, 5c is kept constant.

Then, the flow rate control device 23a, 23b, 23c, the actual flow rate signal La, Lb, Lc and the proper flow rate signal Sa, Sb, Sc input from the flow rate detection device 21a, 21b, 21c and the conversion device 25a, 25b, 25c. Are compared with each other, and the former is matched with the latter, and the flow rate of the cooling water flowing through each bypass pipe 19a, 19b, 19c is adjusted and controlled to an appropriate flow rate.

 Next, the operation of the above embodiment will be described.

The total flow rate of the cooling water as a cooling fluid supplied in the liquid phase from the outside is adjusted by the main flow rate adjusting valve 15 to the rated flow rate at the full load operation of the fuel cell, and the main supply pipe 7 and the inlet pipes 9a, 9b. , 9c, fixed throttles 17a, 17b, 17c, and inlet manifolds 6a, 6b, 6c, and cooling plates 5 of the fuel cell stacks 3a, 3b, 3c.
It flows into a, 5b, 5c.

In this case, fixed throttles 17a, 17 in the inlet pipes 9a, 9b, 9c
The flow rates on the downstream side of b and 17c are substantially the same in each of the inlet pipes 9a, 9b and 9c. During full load operation, the inlet pipes 9a, 9b,
All the cooling water from 9c is supplied to each cooling plate 5a, 5b, 5c through each inlet manifold 6a, 6b, 6c, and the flow rate of each cooling plate 5a, 5b, 5c is made uniform.

The cooling plates 5a, 5b, 5c absorb the heat generated in the unit cell 1,
Each outlet manifold 10a, 10b, 10c, outlet piping 13a, 13b, 13c
Through the main outflow pipe 11.

Here, when partial load operation is performed due to changes in operating conditions of the fuel cell, each fuel cell stack 3a, 3b,
The power generation amount in 3c is detected by the detection means 27a, 27b, 27c, and the detection signals Ha, Hb, Hc are output based on the detection result.

The detection signals Ha, Hb, Hc are input to the conversion devices 25a, 25b, 25c, and the detection signals Ha, Hb, H in the conversion devices 25a, 25b, 25c.
Proper flow rate of each bypass pipe 19a, 19b, 19c corresponding to c, in other words, each outlet pipe on the cooling plate outlet side according to the amount of power generation
An appropriate flow rate is set to maintain a constant quality at the point upstream of the confluence of 13a, 13b, 13c and each bypass pipe 19a, 19b, 19c, and the appropriate flow rate signals Sa, Sb, Sc are output based on this. To be done.

On the other hand, in the flow rate detectors 21a, 21b, 21c, each bypass pipe 1
The actual flow rate of the cooling water flowing through 9a, 19b, 19c is detected, and the actual flow rate signals La, Lb, Lc are output based on this.

The flow rate control devices 23a, 23b, 23c are the flow rate detection devices 21a, 21b, 2
1c and the actual flow rate signal L output from the converters 25a, 25b, 25c
The a, Lb, Lc are compared with the appropriate flow rate signals Sa, Sb, Sc, and the flow rates of the cooling water flowing through the bypass pipes 19a, 19b, 19c are adjusted and controlled so that the former matches the latter.

Therefore, the cooling plates 5a, 5b, 5c of each fuel cell stack 3a, 3b, 3c
The cooling water flowing through is controlled in accordance with the heat generation amount of the partial load operation of each fuel cell stack 3a, 3b, 3c, and each outlet pipe 13a, 13b, 13c of the outlet side of each cooling plate 5a, 5b, 5c The quality is close to the quality of the fuel cell at full load operation. Therefore, there is no risk of unstable flow of the cooling water flowing through the cooling plates 5a, 5b, 5c.

Further, since the flow rate of the cooling water flowing through the main supply pipe 7 is constant by the action of the main flow rate adjusting valve 15 regardless of the full load or partial load operation, the fixed throttles provided in the respective inlet pipes 9a, 9b, 9c. The flow rate of the cooling water after passing through 17a, 17b, 17c is always substantially uniform for each inlet pipe 9a, 9b, 9c regardless of the change in the operating conditions of the fuel cell.

Therefore, the flow rate of the cooling water flowing through each cooling plate is also made substantially uniform, and it is possible to generate power with extremely high efficiency.

Explaining the above action specifically using a graph, for example, the calorific value of each fuel cell stack 3a, 3b, 3c becomes 1/2 with respect to full load operation, and each fuel cell stack 3a, 3b, 3c If the flow rate of the cooling water required to cool the fuel cell is set to be proportional to the heat value, the bypass pipe 1 of one fuel cell stack 3a (3b, 3c)
The proper flow rate of the cooling water flowing through 9a (19b, 19c) is 1/6 of the rated flow rate (total flow rate) (since three bypass pipes are provided in this embodiment). When numerical analysis is performed using this value, as shown by the line segment in FIG. 3, there is a change in the flow rate ratio to the average flow rate of plus or minus 5%, and in line segment a in FIG. As shown, the quality at the outlet side of each cooling plate 5a, 5b, 5c is up to 1.5.
%, The minimum is 1.2%, compared to the case of the conventional example (total flow rate: 1/2 rated flow rate) shown by the line segment in FIG. 3 and the line segment a in FIG. (Line segment in the figure,
It is clear that the changes to a) are significantly suppressed and are greatly improved as described above.

Furthermore, the flow rate of the cooling water supplied to the main supply pipe 7 is constant, no external control is required, and the structure can be simplified.

FIG. 2 shows another embodiment of the present invention. In this embodiment, the flow rate detectors 21a, 21b, 21c are connected to the inlet pipes 9a,
The appropriate flow rate signal S output by the converters 25a, 25b, 25c, which is provided downstream of the branch points of the bypass pipes 19a, 19b, 19c of 9b, 9c, and is output.
a, Sb, Sc are cooling plates 5a, 5b, 5c of each fuel cell stack 3a, 3b, 3c
It is configured to set an appropriate flow rate of the cooling water supplied to the.

As a result of the numerical analysis according to this embodiment, the flow rate ratio is plus / minus 10% as shown by the line segment in FIG.
And the quality on the outlet side of each cooling plate 5a, 5b, 5c is also a change of 1.4% at the maximum and 1.3% at the minimum, as shown by the line segment a in FIG. As in the above-described embodiment, it is clear that the line segment of FIG. 3 and the line segment a of FIG.

In this way, regardless of changes in operating conditions, the main supply pipe 7
While supplying the rated flow of cooling water to each cooling plate 5a, 5b,
The cooling water can be supplied to the 5c at substantially the same flow rate, and the quality change on the outlet side of each cooling plate 5a, 5b, 5c can be significantly suppressed, and extremely efficient power generation can be performed. .

The present invention is not limited to the above embodiment. As the factors detected by the detecting means 27a, 27b, 27c, by detecting the central temperature of each unit cell 1, the fuel supply amount, etc., cooling is performed according to the fluctuation of the heat generation amount due to the partial load operation of the fuel cell stack. It can also be configured to control the flow rate of the cooling fluid through the plate.

[Brief description of drawings]

FIG. 1 is a cooling system diagram of a fuel cell cooling device according to an embodiment of the present invention, FIG. 2 is a cooling system diagram of another embodiment of the present invention, and FIG. 3 is cooling supplied to each cooling plate. The figure showing the comparison between the example of the present invention and the conventional example for the flow rate ratio of water,
FIG. 4 is a diagram showing a comparison between the embodiment of the present invention and a conventional example regarding the quality of each cooling plate outlet side of each fuel cell stack, FIG. 5 is a cooling system diagram of the conventional example, and FIG. It is a cooling system diagram. (Explanation of the symbols indicating the main parts of the drawing) 1 ... Unit cells 3a, 3b, 3c ... Fuel cell stack 5a, 5b, 5c ... Cooling plate 9a, 9b, 9c ... Inlet piping 13a, 13b, 13c ...... Outlet pipe 17a, 17b, 17c …… Fixed throttle 19a, 19b, 19c …… Bypass pipe 21a, 21b, 21c …… Flow detector 23a, 23b, 23c …… Flow controller 25a, 25b, 25c …… Conversion Devices 27a, 27b, 27c ... Detection means

Claims (1)

[Claims] 1. A fuel cell stack comprising a plurality of unit cells stacked one above the other, with a plurality of upper and lower fuel cell stacks having cooling plates interposed at the upper and lower ends and in the middle thereof. A main supply pipe for supplying a cooling liquid to each cooling plate of the body, each inlet pipe branched from the main supply pipe corresponding to each fuel cell stack, and each fuel cell stack from each inlet pipe Each inlet manifold connected to each cooling plate of the body, each outlet manifold connected to each cooling plate of each fuel cell stack, main outlet pipe for collecting the cooling liquid, each outlet manifold and the main flow In a fuel cell provided with each outlet pipe connecting the outlet pipe, a flow rate of the cooling liquid corresponding to the cooling liquid flow rate during the rated operation of the plurality of fuel cell stacks is almost constant in each fuel cell stack. Each said inlet to be supplied equally A plurality of fixed throttles provided in the pipes, a plurality of bypass pipes connected to the outlet pipes from the downstream side of the fixed throttles, and a cooling liquid supplied to the cooling plate of each fuel cell stack. A plurality of flow rate detection devices that detect a flow rate and output an actual flow rate signal, a plurality of detection means that detect a factor capable of confirming a change in heat generation amount due to a change in operating conditions of each fuel cell stack, and each detection A plurality of converters that set an appropriate flow rate of the cooling liquid supplied to each fuel cell stack based on each factor output from the means and output an appropriate flow rate signal; and an actual input from each of the flow rate detection devices. The flow rate of the cooling liquid flowing through each of the bypass pipes in order to control the flow rate of the cooling liquid supplied to each of the fuel cell stacks by comparing the flow rate signal with the appropriate flow rate signal input from each of the converters. Controllable multiple And a control device for controlling the flow rate of the cooling liquid flowing through the cooling plate in each of the fuel cell stacks according to the fluctuation of the heat generation amount due to the partial load operation of each fuel cell stack. Characteristic fuel cell.