JP4925078B2 - Polymer electrolyte fuel cell - Google Patents

Description

  The present invention relates to a polymer electrolyte fuel cell, and in particular, a polymer electrolyte fuel in which a part of cooling water supplied to a fuel cell main body is diverted and gas such as air contained in the cooling water is discharged. It relates to batteries.

  As is well known, a polymer electrolyte fuel cell is provided with an anode (fuel electrode) and a cathode (air electrode) on both sides of a solid polymer electrolyte membrane, and a separator provided with a gas channel on both sides thereof. A fuel cell (usually a reformed gas mainly composed of hydrogen) is circulated through the gas flow path of the separator that forms the battery cell and is joined to the anode, and an oxidant gas (usually a separator gas that is joined mainly to the cathode). , Air) is circulated to cause a chemical reaction through the solid polymer electrolyte membrane, thereby generating an electromotive force. Further, in order to obtain a required electromotive force, a large number of the battery cells are stacked in units, and end plates are attached to both ends of the battery cells, and the fuel cell main body (stack) is integrated by tightening to an appropriate pressure with a rod or the like. Composed.

  In the solid polymer fuel cell, since the chemical reaction is an exothermic reaction, cooling water is supplied to the fuel cell main body to cool the fuel cell main body so as to maintain an optimum operating temperature (about 80 ° C.). Therefore, a plurality of cooling water plates for circulating the cooling water in the fuel cell main body are interposed, or a cooling water flow path is provided on the back side of any one of the separators, and the cooling water is distributed and supplied to these. A cooling water flow path is formed by providing a supply manifold for discharging and a discharge manifold for joining the discharged cooling water and discharging it to the outside.

  The cooling water supplied to the fuel cell main body is usually pumped up from a cooling water tank, and the pumped cooling water is supplied to the supply manifold to cool the fuel cell main body. After cooling, the cooling water is discharged from the discharge manifold. The cooling water is returned to the cooling water tank. However, air may be mixed in the cooling water flow path at the time of starting or stopping, or fine gas bubbles may be included in the cooling water, and thus air or gas exists in the cooling water. If this occurs, the supply of cooling water to the fuel cell body will be hindered, resulting in a shortage of cooling water supply or uneven distribution, resulting in a large temperature distribution inside the battery, resulting in a decrease in power generation performance of the fuel cell body. there were.

As means for solving such problems, conventionally, several air discharge means (air / water separation) are provided in the cooling water circulation path to be supplied to the fuel cell main body as in, for example, Patent Document 1, and air or the like is provided in the cooling water. A technique is known in which gas such as air is prevented from flowing into a fuel cell body by separating air and water with an air discharge means even if gas is contained.
JP 2003-123805 A

  However, in the above prior art, the pipe diameter must be increased in order to improve the gas venting efficiency in the air discharge means, and a plurality of air discharge means are required, so that a large installation space is required. This will increase the size of the system. Further, since a water level detection sensor or the like for controlling the venting is installed, the cooling water flow path becomes complicated and the cost increases. Furthermore, in the conventional polymer electrolyte fuel cell, although cooling water is supplied to the fuel cell main body and kept at the optimum operating temperature, both ends of the fuel cell main body are close to the outside air, so the temperature is higher than other parts. There is a problem that the power generation performance of the battery cells located near both ends is lowered.

  The present invention has been made to solve such problems of the prior art, and can suppress an increase in the size of the fuel cell system without requiring an air discharge means, a cooling water circuit having a large pipe diameter, a water level detection sensor, or the like. In addition, a part of the cooling water supplied to the fuel cell main body is diverted to discharge gas such as air contained in the cooling water, and the cooling water is supplied to both ends of the fuel cell main body to suppress the temperature drop. An object of the present invention is to provide a solid polymer fuel cell.

As a means of the present invention for achieving the above object, the present invention provides a cooling water supply port (firstly provided) in which a large number of unit battery cells are stacked in a surface-bonded state and provided in the upper part so as to penetrate in the stacking direction. Manifold), a cooling water supply port (second manifold) into which most of the cooling water flowing through the cooling water supply port (first manifold) flows, and the cooling water provided from the top to the bottom. A water flow path in which the cooling water from the supply port (second manifold) flows from the top to the bottom in each unit cell, and a cooling water drain port (third manifold) provided in the lower part and through which the cooling water from the water flow path flows And a fuel cell main body having a cooling water drain port (fourth manifold) provided at a lower portion and through which cooling water from the cooling water drain port (third manifold) flows,
A cooling water supply path is provided above the fuel cell main body,
Cooling water that is connected at the back end opposite to the inlet of the cooling water supply port (first manifold), extends upward from the fuel cell body, and flows through the cooling water supply port (first manifold). A diversion path in which a part of the diversion path is diverted, and a branch path where the cooling water diverted in the diversion path is bifurcated.
The cooling water is returned to the cooling water tank through the cooling water drain port (fourth manifold) and the cooling water discharge passage through which the cooling water from the branch passage flows, and the cooling water is supplied from the cooling water tank to the cooling water. A cooling water circulation path configured to send out toward the road,
A partition plate that is gradually inclined upward toward the back end portion of the cooling water supply port (first manifold) along the flow direction of the cooling water supplied from the cooling water supply channel is provided with the cooling water supply port (first 1 manifold),
The diversion path is configured by a narrow pipe having a smaller diameter than the cooling water discharge path, and is configured to have a larger pressure loss than the cooling water discharge path,
It is characterized by a polymer electrolyte fuel cell configured to supply cooling water of a branch path branched in a diversion path to both ends of the fuel cell main body to suppress a temperature drop.

  According to the first aspect of the present invention, since the diversion path for diverting a part of the cooling water from the cooling water supply port provided in the fuel cell main body is provided, a part of the cooling water is utilized using the diversion path. The gas such as air contained in the cooling water can be discharged by dividing the gas.

  According to the first aspect of the present invention, since the pressure distribution in the diversion path is larger than that in the cooling water circulation path, most of the cooling water supplied to the cooling water supply port of the fuel cell main body is cooling water. It distribute | circulates to a plate and can divert only a part of cooling water to a diversion path.

  According to the first aspect of the present invention, since the inlet end portion of the diversion path is provided in an upper region of the cooling water supply port, a gas such as air that easily collects in the upper region of the cooling water supply port. Can be discharged efficiently.

  According to the first aspect of the present invention, the cooling water supply port is provided with the partition plate that is gradually inclined upward along the cooling water flow direction, and the flow dividing path is located at the back end of the cooling water supply port. Therefore, gas such as air can be more easily collected at the back end of the cooling water supply port, and can be efficiently discharged.

  According to the first aspect of the present invention, the cooling water branched into the two branch paths, the cooling water branched into one branch path is circulated through one end plate of the fuel cell stack, and the cooling water branched into the other branch path Is circulated through the other end plate of the fuel cell stack, so that both ends of the fuel cell main body can be warmed by the heat of the cooling water, thereby suppressing the temperature drop of the battery cells located at the end.

Next, an embodiment of a polymer electrolyte fuel cell according to the present invention will be described with reference to the accompanying drawings.
In the accompanying drawings, FIG. 1 is a schematic configuration diagram showing a reference example 1 for explaining the basic principle of a polymer electrolyte fuel cell according to the present invention. FIG. 2 is a schematic perspective view of a fuel cell main body according to the first reference example . FIG. 3 is a schematic longitudinal sectional side view showing the cooling water flow path of the fuel cell main body according to Reference Example 1. FIG. FIG. 4 is a schematic longitudinal sectional front view showing a cooling water flow path and the like of the fuel cell main body according to Reference Example 1 . FIG. 5 is a schematic configuration diagram showing an embodiment of a polymer electrolyte fuel cell according to the present invention. FIG. 6 is a schematic configuration diagram showing a modification of the polymer electrolyte fuel cell according to the present invention.

[ Reference Example 1]
In FIG. 1, reference numeral 1 denotes a fuel cell main body, schematically showing an anode 2 and a cathode 3 which are part of the constituent elements, and a cooling water plate 4 positioned therebetween. The fuel cell main body 1 is actually provided with an anode 2 and a cathode 3 on both sides of a solid polymer electrolyte membrane 5 as shown schematically in FIG. Separators 6 and 7 are arranged to form unit battery cells 8, a large number of unit battery cells 8 are stacked in a surface-bonded state, end plates 9 and 10 are attached to both ends, and tightened with a rod (not shown) or the like. It is configured as a stack.

  In the fuel cell body 1, fuel gas (usually a reformed gas mainly composed of hydrogen) is circulated through the gas flow path of the separator 6 joined to the anode 2, and the gas flow of the separator 7 joined to the cathode 3. Electricity is generated by causing an oxidant gas (usually air) to flow through the path and causing a chemical reaction through the solid polymer electrolyte membrane 5.

  Usually, a plurality of the cooling water plates 4 are incorporated between the unit battery cells 8, but a case where the cooling water plate 4 is configured by forming a water flow path on the back side of the separator 6 or the separator 7. There is also. The cooling water is supplied to the cooling water plate 4 as shown in FIGS. 2 and 3, for example, in the cooling water supply port 11 (hereinafter referred to as the first manifold) provided in the upper part of the fuel cell main body 1 in the stacking direction. And a recessed cooling water supply port 4a (hereinafter referred to as a second manifold) provided in the upper portion of the cooling water plate 4 in communication with the first manifold 11 and in communication with the second manifold 4a. This is performed via a groove-shaped water flow path 4b arranged in parallel in the vertical direction of the cooling water plate 4. That is, the cooling water in the cooling water tank 14 is supplied to the inlet 11 a (FIG. 3) of the first manifold 11 after the water temperature is adjusted through the heat exchanger 19 by the operation of the pump 15. While flowing, it is distributed in the second manifold 4a (FIG. 2) of each cooling water plate 4, and is supplied from the second manifold 4a to each water flow path 4b.

  The cooling water that has flowed down the cooling water plate 4 in the direction of gravity communicates with each of the water flow paths 4b as shown in FIG. The cooling water discharge port 12 (hereinafter referred to as the fourth manifold) provided in the lower portion of the fuel cell main body 1 and penetrating in the stacking direction is communicated with the third manifold 4c. Then, the cooling water discharged from each cooling water plate 4 joins and is discharged to the outside from the outlet 12a (FIG. 3) of the fourth manifold 12.

In the present invention, as in the first reference example, a diversion path for diverting a part of the cooling water supplied to the fuel cell main body 1 is provided at a position higher than the fuel cell main body 1. For example, the diversion path 13 shown in FIG. 3 is connected to the upper end of the first manifold 11, that is, the upper end of the first manifold 11 opposite to the inlet 11 a (closed by the end plate 10). It extends upward. In order to increase the pressure loss more than the cooling water circulation path 16, particularly the cooling water supply path 16 a, the diversion path 13 is composed of, for example, a narrow pipe having a smaller diameter than the pipe of the cooling water supply path 16 a. The upper region of the back end portion of the first manifold 11 to which the cooling water is supplied is a place where gas such as air contained in the cooling water is easily collected, and the cooling water is connected by connecting the diversion path 13 therewith. A part of the air can be sucked and diverted, and at the same time, gas such as accumulated air can be sucked and discharged. At this time, most of the cooling water supplied to the first manifold 11 is circulated to the second manifold 4a of each cooling water plate 4 and only a part (about 5%) of the cooling water is diverted to the diversion path 13. Therefore, as described above, the pressure loss of the diversion path 13 is set large.

  Further, as shown in FIG. 3, when a partition plate 20 that is gradually inclined upward along the coolant flow direction is provided inside the first manifold 11, the rear end portion of the first manifold 11 is provided by the partition plate 20. It becomes easier for gas such as air to accumulate in the upper region of. Thereby, gas, such as air contained in cooling water, can be discharged efficiently.

  As shown schematically in FIG. 1, the branch path 13 is bifurcated in the middle, one branch path 13a is connected to the vicinity of the outlet 12a of the fourth manifold 12, and the other branch path 13b is a cooling water circulation path. It is connected to 16 cooling water discharge paths 16b. These branch passages 13a and 13b are made longer by using a spiral pipe than in the case of a straight pipe, thereby increasing the pressure loss. In this case, the diversion path 13 can be implemented by one spiral pipe without branching into two branches.

The diversion path 13 is not limited to the case where it is connected to the back end portion of the first manifold 11 in the fuel cell main body 1 as described above. For example, as shown in FIG. 4, the diversion path 13 is connected to the second manifold 4a in the cooling water plate 4. You may do it. Even when the flow dividing path 13 is provided in the second manifold 4a, the second manifold 4a is connected to the upper end of the rear end of the second manifold 4a, that is, the end opposite to the first manifold 11, and extends upward from the fuel cell body 1. To do. In order to increase pressure loss more than the cooling water circulation path 16, particularly the cooling water supply path 16a, the diversion path 13 is constituted by, for example, a narrow tube having a smaller diameter than the pipe of the cooling water supply path 16a. The upper region of the back end portion of the second manifold 4a to which the cooling water is supplied from the first manifold 11 is a place where gas such as air mixed in the cooling water is easily collected, and the flow dividing path 13 is connected thereto. In this way, a part of the cooling water can be sucked and diverted, and at the same time, gas such as accumulated air can be sucked and discharged. At this time, in order to distribute most of the cooling water supplied to the second manifold 4 a to the water flow path 4 b of the cooling water plate 4 and to divert only a part (about 5%) of the cooling water to the diversion path 13. As described above, the pressure loss of the diversion path 13 is set large. Further, if a partition plate 21 inclined upward along the coolant flow direction (in this case, the coolant inflow direction) is provided inside the second manifold 4a, the rear end of the second manifold 4a is provided by the partition plate 21. Gas such as air is more easily collected in the upper region of the section. Thereby, gas, such as air contained in cooling water, can be discharged efficiently. When the diversion path 13 is connected to the second manifold 4a, each cooling water plate 4 is provided with a merging means (not shown) for merging the diversion paths 13 on the way.

[ Embodiment]
Figure 5 shows an embodiment of a polymer electrolyte fuel cell according to the present invention, the above reference example 1 and the same components are omitted and the detailed description thereof given the same reference numerals. In the present embodiment, the cooling water diverted through the diversion path 13 is circulated through the end plates 9 and 10 on both sides of the fuel cell main body 1, thereby reducing the temperature drop of the unit battery cells located at both ends of the fuel cell main body 1. It is something to be suppressed.

  In FIG. 5, one branch path 13 a branched from the diversion path 13 supplies and circulates cooling water to one end plate 9 in the fuel cell main body 1 and is connected to the vicinity of the outlet 12 a of the fourth manifold 12. The other branch path 13b supplies and circulates cooling water to the other end plate 10 of the fuel cell main body 1 and is connected to the cooling water discharge path 16b of the cooling water circulation path 16. The end plates 9 and 10 are each provided with a plurality of perforated water flow paths (not shown) for circulating cooling water in parallel with each other, or recessed groove water flow paths (not shown) are arranged in parallel on the inner surface side. The upper part is provided with a supply port (not shown) communicating with the inlet of each water channel, and the lower part is provided with a discharge port (not shown) communicating with the outlet of each water channel.

  The cooling water discharged from the fourth manifold 12 of the fuel cell main body 1 has a temperature close to an appropriate operating temperature (about 80 ° C.) of the fuel cell main body 1, and this cooling water is the cooling water in the cooling water circulation path 16. It returns to the cooling water tank 14 through the discharge path 16b. The temperature of the cooling water in the cooling water tank 14 gradually rises, and the temperature of the temperature rising cooling water is adjusted through the heat exchanger 19 by the operation of the pump 15, and the fuel passes through the cooling water supply path 16 a of the cooling water circulation path 16. It is supplied to the first manifold 11 of the battery body 1. The cooling water supplied to the first manifold 11 flows from the second manifold 4 a of each cooling water plate 4 through the water flow path 4 b and exchanges heat with the adjacent separator 6 or separator 7. Thereby, the inside of the fuel cell main body 1 is cooled and maintained at an appropriate operating temperature (about 80 ° C.), and the cooling water discharged from the fourth manifold 12 is warmed to about 80 ° C.

  The diversion path 13 can divert part of the cooling water supplied to the first manifold 11 as described above, and at the same time, discharge gas such as air contained in the cooling water. Then, the cooling water flowing into the branch paths 13a and 13b from the branch path 13 is supplied to the end plates 9 and 10 located at both ends of the fuel cell main body 1 as described above, so that these end plates 9 10 can be warmed. As a result, the temperature drop of the unit battery cells adjacent to the end plates 9 and 10 can be suppressed and maintained at an appropriate temperature of 80 ° C., and the deterioration of the power generation performance in the unit battery cell located at the end can be suppressed. Can do.

  In the above embodiment, the diversion path 13 is bifurcated. However, the first diversion path (not shown) is provided in the first manifold 11, and the second diversion path (not shown) in the second manifold 4a. ) May be provided, and two shunt paths may be used in combination. In the second embodiment, it is desirable to supply the coolant through the diversion path 13 almost uniformly to the end plates 9 and 10 of the fuel cell main body 1, and therefore, the diversion path 13 is preferably bifurcated. .

[ Reference Example 2]
FIG. 6 shows a modification of the polymer electrolyte fuel cell according to the present invention (hereinafter referred to as “Reference Example 2”) , and the same components as those in Reference Example 1 or the above embodiment are denoted by the same reference numerals. A detailed description thereof will be omitted. In the present reference example , the cooling water divided by the diversion path 13 is circulated through the air humidifier 17 to humidify the oxidant gas (air) supplied to the fuel cell main body 1.

  In FIG. 6, reference numeral 17 denotes an air humidifier in which a moisture permeable membrane (not shown) is disposed. The air humidifier humidifies the air taken in from the outside and the cathode of the fuel cell main body 1 by the air supply path 18 a of the air circulation path 18. 3 and the remaining unreacted air that has not been used for the power generation reaction at the cathode 3 is returned to the air humidifier 17 by the air discharge path 18b and is discharged from the air humidifier 17 to the outside. In the air humidifier 17, the region through which air taken in from outside flows and the region through which unreacted air returned from the air discharge path 18b flows are partitioned by the moisture permeable membrane.

  The branch paths 13a and 13b of the diversion path 13 are connected to the air discharge path 18b of the air circulation path 18, respectively. In addition, it is also possible to implement with one spiral pipe without branching the diversion path 13 into two branches.

  The diversion path 13 can divert part of the cooling water supplied to the first manifold 11 of the fuel cell main body 1 and simultaneously discharge a gas such as air contained in the cooling water. The cooling water that has flowed into the branch paths 13a and 13b from the branch path 13 is supplied into the air discharge path 18c of the air circulation path 18, and is thus discharged from the cathode 3 of the fuel cell main body 1 to the air discharge path. Mix with unreacted air flowing in 18b. The unreacted air in the gas-liquid mixed state flows through the air humidifier 17, and at that time, moisture is absorbed by the moisture permeable membrane.

  Since the air taken in from the outside flows through the other region partitioned by the moisture permeable membrane, the air is humidified by the moisture evaporated from the moisture permeable membrane. That is, moisture exchange is performed between the unreacted air in the gas-liquid mixed state that is in contact with the moisture permeable membrane and the air taken from the outside. The air humidified by the air humidifier 17 is supplied as an oxidant gas from the air supply path 18a to the cathode 3 of the fuel cell body 1, and the dehumidified unreacted air is discharged from the air humidifier 17 to the outside. Thereby, the bubbling means for humidification etc. which were conventionally used become unnecessary.

In the embodiment and the modification described above, an example in which the diversion path 13 is bifurcated has been described. However, the first diversion path (not shown) is provided in the first manifold 11, and the second diversion flow is provided in the second manifold 4a. A path (not shown) may be provided, and two shunt paths may be used in combination. In the above-described embodiment , it is desirable to supply the cooling water by the diversion path 13 almost uniformly to the end plates 9 and 10 of the fuel cell main body 1, and therefore, the diversion path 13 is preferably bifurcated.

  The polymer electrolyte fuel cell according to the present invention can be applied by being incorporated as a power generation means in a stationary fuel cell power generation system, a cogeneration system co-generation with heat and power, or other devices and devices.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram showing a reference example 1 for explaining a basic principle of a polymer electrolyte fuel cell according to the present invention. 2 is a schematic perspective view of a fuel cell main body according to Reference Example 1. FIG. It is a schematic longitudinal cross-sectional side view which shows the cooling water flow path of the fuel cell main body which concerns on the reference example 1. FIG. It is a schematic longitudinal cross-sectional front view which shows embodiment of the fuel cell main body which concerns on the reference example 1. FIG. 1 is a schematic configuration diagram showing an embodiment of a polymer electrolyte fuel cell according to the present invention. It is a schematic block diagram which shows the reference example 2 which is a modification of the polymer electrolyte fuel cell which concerns on this invention.

1 Fuel Cell Body 2 Anode 3 Cathode 4 Cooling Water Plate 4a Cooling Water Supply Port (Second Manifold)
4b Water channel 4c Cooling water outlet (third manifold)
5 Solid polymer electrolyte membrane 6, 7 Separator 8 Unit battery cell 9, 10 End plate 11 Cooling water supply port (first manifold)
11a Partition plate 12 Cooling water outlet (fourth manifold)
13 Branch path 13a, 13b Branch path 14 Cooling water tank 15 Pump 16 Cooling water circulation path 16a Cooling water supply path 16b Cooling water discharge path 17 Air humidifier 18 Air distribution path 18a Air supply path 18b Air discharge path 19 Heat exchanger 20, 21 Partition plate

Claims (1)

A large number of unit battery cells are stacked in a surface-bonded state, and a cooling water supply port (first manifold) provided penetrating in the stacking direction in the upper part and the cooling water supply port (first manifold) provided in the upper part are provided. A cooling water supply port (second manifold) into which most of the circulating cooling water flows and a cooling water from the cooling water supply port (second manifold) provided from the upper part to the lower part passes through each unit cell. From the cooling water drain port (third manifold) provided in the lower part and the cooling water drain port (third manifold) provided in the lower part. A fuel cell body having a cooling water drainage port (fourth manifold) through which water flows;
A cooling water supply path is provided above the fuel cell main body,
Cooling water that is connected at the back end opposite to the inlet of the cooling water supply port (first manifold), extends upward from the fuel cell body, and flows through the cooling water supply port (first manifold). A diversion path in which a part of the diversion path is diverted, and a branch path where the cooling water diverted in the diversion path is bifurcated.
The cooling water is returned to the cooling water tank through the cooling water drain port (fourth manifold) and the cooling water discharge passage through which the cooling water from the branch passage flows, and the cooling water is supplied from the cooling water tank to the cooling water. A cooling water circulation path configured to send out toward the road,
A partition plate that is gradually inclined upward toward the back end portion of the cooling water supply port (first manifold) along the flow direction of the cooling water supplied from the cooling water supply channel is provided with the cooling water supply port (first 1 manifold),
The diversion path is configured by a narrow pipe having a smaller diameter than the cooling water discharge path, and is configured to have a larger pressure loss than the cooling water discharge path,
A polymer electrolyte fuel cell, characterized in that it is configured to supply a cooling water of a branch path branched in a diversion path to both ends of the fuel cell main body to suppress a temperature drop.

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