JP2008181783A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell having simple and economical constitution, easily and surely draining produced water from reaction gas passages, and enhancing system efficiency. <P>SOLUTION: A cooling medium inlet manifold 50a for supplying a cooling medium to a cooling medium supply communication hole 32a is mounted on an end plate 24a. A cooling medium flow rate adjusting mechanism 60 corresponding to the cooling medium supply communication hole 32a is installed in the cooling medium inlet manifold 50a. The cooling medium flow rate adjusting mechanism 60 has a butterfly valve 62, the butterfly valve 62 is position-adjusted in first opening P1 and second opening P2 corresponding to the temperature of the medium by the balance of torque corresponding to temperatures of a shape-memory alloy spring member 66a and a usual metal spring member, and a cooling medium supply flow rate supplied to the cooling medium supply communicating hole 32a is adjusted. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  In the present invention, an electrolyte membrane / electrode structure provided with a pair of electrodes on both sides of an electrolyte membrane and a separator are stacked, and a reaction gas flow path for supplying a reaction gas along the electrode surface is formed. The present invention relates to a fuel cell in which a cooling medium flow path is formed that supplies a cooling medium in a direction that intersects a reaction gas flow direction of the reaction gas flow path and that extends along the electrode surface.

  For example, a polymer electrolyte fuel cell has a power generation cell in which an electrolyte membrane / electrode structure in which an anode side electrode and a cathode side electrode are arranged on both sides of an electrolyte membrane made of a polymer ion exchange membrane is sandwiched by separators. I have. This type of fuel cell is normally used as a fuel cell stack by stacking a predetermined number of power generation cells.

  In the above fuel cell, a fuel gas channel (reaction gas channel) for flowing fuel gas to the anode side electrode and an oxidant gas channel for flowing oxidant gas to the cathode side electrode in the plane of the separator (Reactive gas flow path) is provided. Furthermore, between the separators, a cooling medium flow path for flowing the cooling medium is provided along the surface direction of the separator.

  By the way, in the cathode side electrode, generated water is generated by the power generation reaction, and this generated water moves to the downstream side along the oxidant gas flow path and is easily condensed to form water droplets. For this reason, the condensed water tends to stay downstream (exit) of the oxidant gas flow path, the oxidant gas flow path may be blocked, and deterioration of the electrolyte membrane may be promoted.

  Thus, for example, a fuel cell disclosed in Patent Document 1 is known. In this fuel cell, as shown in FIG. 9, a cooling plate 1 is interposed between the single cells, and the cooling plate 1 is formed with two channels 2a and 2b for cooling water. . Temperature control water W1 having a first temperature T1 is passed through one flow path 2a, and temperature control water W2 having a second temperature T2 lower than the first temperature T1 is passed through the other flow path 2b. ing.

  Specifically, the first circulation channel 3 is connected to the channel 2a, and the second circulation channel 4 is connected to the channel 2b. The circulation channels 3 and 4 are provided with radiators 6a and 6b provided with fans 5a and 5b, respectively, and circulation pumps 7a and 7b. The circulation pumps 7 a and 7 b are connected to the electronic control unit 8.

  Accordingly, the circulation pumps 7a and 7b are driven and controlled via the electronic control unit 8, whereby the temperature-controlled water W1 having the first temperature T1 flows through the flow path 2a, while the second temperature T2 flows through the flow path 2b. Temperature control water W2 flows. As a result, a temperature gradient along the cathode gas flow is obtained, and the relative temperature of the gas in the power generation surface and the condensed state of the generated water are made uniform to stabilize power generation.

Japanese Patent Laid-Open No. 7-320755 (FIG. 4)

  However, in Patent Document 1, circulation channels 3 and 4 are connected to the respective channels 2a and 2b, and the circulation channels 3 and 4 include radiators 6a and 6b including fans 5a and 5b. Circulation pumps 7a and 7b are provided. As a result, problems have been pointed out that the entire system becomes larger and the cost increases due to an increase in the number of parts.

  The present invention solves this type of problem, and with a simple and economical configuration, the relative temperature of the gas in the power generation surface and the condensed state of the generated water are made uniform, and the system efficiency is improved satisfactorily. An object of the present invention is to provide a fuel cell capable of satisfying the requirements.

  In the present invention, an electrolyte membrane / electrode structure provided with a pair of electrodes on both sides of an electrolyte membrane and a separator are stacked, and a reaction gas flow path for supplying a reaction gas along the electrode surface is formed. The present invention relates to a fuel cell in which a cooling medium flow path is formed that supplies a cooling medium in a direction that intersects a reaction gas flow direction of the reaction gas flow path and extends along the electrode surface.

  The cooling medium flow path communicates with the plurality of cooling medium supply communication holes and the plurality of cooling medium discharge communication holes extending in the stacking direction of the electrolyte membrane / electrode structure and the separator, and the fuel cell includes the plurality of cooling medium supply communication holes. A cooling medium flow rate adjusting mechanism is disposed corresponding to at least one of the cooling medium supply communication holes or the plurality of cooling medium discharge communication holes.

  In addition, a pair of end plates are disposed at both ends of the electrolyte membrane / electrode structure and the separator in the stacking direction, and a cooling medium flow rate adjusting mechanism is integrally disposed within at least one of the end plates. It is preferable. Furthermore, the cooling medium flow rate adjustment mechanism preferably includes a butterfly valve.

  According to the present invention, in the configuration in which the reaction gas flow direction in the reaction gas flow path intersects the cooling medium flow direction in the cooling medium flow path, the flow rate distribution of the cooling medium can be adjusted along the reaction gas flow direction. It is possible to arbitrarily set the temperature distribution in the electrode surface. Therefore, for example, by setting the electrode surface temperature on the reaction gas outlet (downstream in the reaction gas flow direction) side where the amount of generated water is likely to be higher than that of other portions, the relative temperature of the gas in the power generation surface and the generated water It is possible to make the condensed state of the water uniform.

  As a result, the power generation performance of the fuel cell can be satisfactorily maintained over a long period of time with a simple and economical configuration, and the system efficiency can be effectively improved.

  FIG. 1 is an explanatory schematic perspective view of a fuel cell 10 according to the first embodiment of the present invention, and FIG. 2 is an exploded schematic perspective view of a main part of the fuel cell 10.

  The fuel cell 10 includes a unit cell 18 having an electrolyte membrane / electrode structure 12 and a first separator 14 and a second separator 16 that sandwich the electrolyte membrane / electrode structure 12, and the unit cell 18 is in the direction of arrow A. It is configured to be laminated. The first separator 14 and the second separator 16 are constituted by a metal separator or a carbon separator.

  As shown in FIG. 1, terminal plates 20a and 20b, insulating plates 22a and 22b, and end plates 24a and 24b are disposed outward at both ends of the unit cell 18 in the stacking direction. The fuel cell 10 is, for example, integrally held by a box-like casing (not shown) including end plates 24a and 24b configured in a rectangular shape as end plates, or a plurality of tie rods extending in the direction of arrow A. (Not shown) are integrally clamped and held.

  As shown in FIG. 2, the first separator 14 and the second separator 16 have a vertically long shape, and have long sides directed in the direction of gravity (arrow C direction) and short sides directed in the horizontal direction (arrow B direction). Configured.

  The upper edge of the long side direction of the unit cell 18 communicates with each other in the direction of arrow A, and an oxidant gas supply communication hole 26a for supplying an oxidant gas, for example, an oxygen-containing gas, and a fuel gas, for example, A fuel gas supply passage 28a for supplying a hydrogen-containing gas is provided.

  At the lower edge of the long side direction of the unit cell 18, the fuel gas discharge communication hole 28 b for discharging the fuel gas and the oxidant gas discharge for discharging the oxidant gas are communicated with each other in the arrow A direction. A communication hole 26b is provided.

  At one edge of the unit cell 18 in the short side direction (arrow B direction), there are provided two upper and lower cooling medium supply communication holes 30a and 32a communicating with each other in the arrow A direction for supplying the cooling medium. The upper and lower two cooling medium discharge communication holes 30b and 32b for discharging the cooling medium are provided at the other end edge of the unit cell 18 in the short side direction.

  The electrolyte membrane / electrode structure 12 includes, for example, a solid polymer electrolyte membrane 34 in which a perfluorosulfonic acid thin film is impregnated with water, and a cathode side electrode 36 and an anode side electrode 38 that sandwich the solid polymer electrolyte membrane 34. With.

  The cathode side electrode 36 and the anode side electrode 38 are uniformly coated on the surface of the gas diffusion layer with a gas diffusion layer (not shown) made of carbon paper or the like, and porous carbon particles carrying a platinum alloy on the surface. An electrode catalyst layer (not shown). The electrode catalyst layers are formed on both surfaces of the solid polymer electrolyte membrane 34.

  An oxidant gas flow path (reactive gas flow path) 40 communicating the oxidant gas supply communication hole 26a and the oxidant gas discharge communication hole 26b is formed on the surface 14a of the first separator 14 facing the electrolyte membrane / electrode structure 12. Is formed. The oxidizing gas channel 40 has a plurality of linear channel grooves 40a extending in the direction of arrow C.

  A fuel gas flow path (reactive gas flow path) 42 that connects the fuel gas supply communication hole 28a and the fuel gas discharge communication hole 28b is formed on the surface 16a of the second separator 16 facing the electrolyte membrane / electrode structure 12. The The fuel gas channel 42 has a plurality of linear channel grooves 42 a extending in the direction of arrow C.

  Between the surface 16b of the second separator 16 and the surface 14b of the first separator 14, a cooling medium flow path 44 communicating with the cooling medium supply communication holes 30a and 32a and the cooling medium discharge communication holes 30b and 32b is formed. Is done. The cooling medium flow path 44 has a plurality of linear flow path grooves 44a extending in the direction of arrow B. The cooling medium flow path 44 may be partitioned up and down by a partition wall 44b at a substantially intermediate height position in the arrow C direction.

  Although not shown, a sealing member is disposed between the electrolyte membrane / electrode structure 12 and the first separator 14 and the second separator 16 and between the first separator 14 and the second separator 16. .

  As shown in FIG. 1, the end plate 24a has an oxidant gas inlet manifold 46a communicating with the oxidant gas supply communication hole 26a, a fuel gas inlet manifold 48a communicating with the fuel gas supply communication hole 28a, and an oxidant gas discharge communication. An oxidant gas outlet manifold 46b that communicates with the hole 26b and a fuel gas outlet manifold 48b that communicates with the fuel gas discharge communication hole 28b are provided at both upper and lower edges.

  A cooling medium inlet manifold 50a that communicates integrally with the cooling medium supply communication holes 30a and 32a and a cooling medium outlet manifold 50b that communicates integrally with the cooling medium discharge communication holes 30b and 32b are provided at both left and right edges of the end plate 24a. Is provided.

  The oxidant gas inlet manifold 46a, the fuel gas inlet manifold 48a, the oxidant gas outlet manifold 46b, the fuel gas outlet manifold 48b, the cooling medium inlet manifold 50a, and the cooling medium outlet manifold 50b are formed of a resin material, and each has a pipeline. 52a, 54a, 52b, 54b, 56a and 56b are integrally provided.

  The end plate 24a is provided with a cooling medium flow rate adjusting mechanism 60 corresponding to at least one of the cooling medium supply communication holes 30a and 32a and the cooling medium discharge communication holes 30b and 32b, for example, the cooling medium supply communication holes 32a. Is done. As shown in FIGS. 3 and 4, the cooling medium flow rate adjusting mechanism 60 is mounted as a unit on the cooling medium inlet manifold 50a.

  The cooling medium flow rate adjusting mechanism 60 includes a butterfly valve 62, and a shaft portion 64 of the butterfly valve 62 is rotatably supported by the unit wall portion 65. A spring member 66a made of a shape memory alloy is attached to one end portion of the shaft portion 64, and a spring member 66b made of a general material is attached to the other end portion.

  When the temperature of the cooling medium is lower than the set temperature, the spring members 66a, 66b are closed side opening positions for reducing the flow rate of the cooling medium supplied to the cooling medium supply communication hole 32a, for example, the first opening. The butterfly valve 62 can be arranged at the position P1. On the other hand, when the temperature of the cooling medium is equal to or higher than the set temperature, the opening side opening position that increases the flow rate of the cooling medium supplied to the cooling medium supply communication hole 32a, for example, the second opening position (fully opened) P2 The butterfly valve 62 can be arranged on the front.

  The operation of the fuel cell 10 configured as described above will be described below.

  First, as shown in FIG. 1, in the fuel cell 10, an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas inlet manifold 46a, and a fuel gas such as a hydrogen-containing gas is supplied to the fuel gas inlet manifold 48a. Is done. Further, a cooling medium such as pure water or ethylene glycol is supplied to the cooling medium inlet manifold 50a.

  As shown in FIG. 2, the oxidant gas is introduced into the oxidant gas flow path 40 of the first separator 14 from the oxidant gas supply communication hole 26 a constituting each unit cell 18, and the electrolyte membrane / electrode structure 12. It moves vertically downward along the cathode side electrode 36.

  On the other hand, the fuel gas is introduced into the fuel gas flow path 42 of the second separator 16 from the fuel gas supply communication hole 28 a constituting each unit cell 18, and vertically along the anode side electrode 38 of the electrolyte membrane / electrode structure 12. Move down.

  As described above, in each electrolyte membrane / electrode structure 12, the oxidant gas supplied to the cathode side electrode 36 and the fuel gas supplied to the anode side electrode 38 are electrochemically reacted in the electrode catalyst layer. It is consumed and power is generated.

  Next, the oxidant gas supplied and consumed to the cathode side electrode 36 is discharged from the oxidant gas discharge communication hole 26b to the oxidant gas outlet manifold 46b (see FIG. 1). Similarly, the fuel gas supplied to the anode side electrode 38 and consumed is discharged from the fuel gas discharge communication hole 28b to the fuel gas outlet manifold 48b.

  Further, after the cooling medium is divided into the cooling medium supply communication holes 30a and 32a in the cooling medium inlet manifold 50a, the cooling medium flow path 44 between the first and second separators 14 and 16 as shown in FIG. To be introduced. The cooling medium flows along the arrow B direction (horizontal direction), cools the electrolyte membrane / electrode structure 12, and is then discharged from the cooling medium discharge communication holes 30b and 32b to the cooling medium outlet manifold 50b.

  In this case, in the first embodiment, the coolant flow rate adjusting mechanism 60 is accommodated in the end plate 24a corresponding to the coolant supply passage 32a. The butterfly valve 62 constituting the cooling medium flow rate adjusting mechanism 60 has a rotational force balance according to the temperature of the shape memory alloy spring member 66a attached to the shaft portion 64 and the general material spring member 66b. The position can be adjusted to the first opening position P1 and the second opening position P2 (see FIG. 4).

  Therefore, when the power generation output of the fuel cell 10 is small, the temperature of the cooling medium circulated and supplied to the fuel cell 10 is low. Therefore, the butterfly valve 62 is disposed at the first opening position P1 depending on the temperature of the cooling medium. Therefore, as shown in FIG. 5, the cooling medium flow rate supplied from the cooling medium supply communication hole 30a to the upper side of the cooling medium flow channel 44 is lower than the cooling medium flow channel 44 from the cooling medium supply communication hole 32a. The flow rate of the cooling medium supplied to the side is reduced.

  At that time, the oxidant gas and the fuel gas are flowing from the vertically upward direction to the downward direction, and the power generation output of the fuel cell 10 is small. Flooding tends to occur on the lower side of the cell 18.

  Here, in the vicinity of the oxidant gas discharge communication hole 26b and the fuel gas discharge communication hole 28b corresponding to the lower side of the cooling medium flow path 44, the flow rate of the cooling medium decreases, so the temperature of the power generation surface tends to rise. . Thereby, in particular, the amount of product water condensed on the outlet side of the oxidant gas flow path 40 can be reduced, and flooding can be prevented.

  Further, during the warm-up operation of the fuel cell 10, the temperature of each unit cell 18 itself is low, the generated water is easily condensed, and the temperature of the circulating cooling medium is low. Therefore, similarly to the above, the butterfly valve 62 is disposed at the first opening position P1, so that the flow rate of the cooling medium supplied to the lower side of the cooling medium flow path 44 can be reduced. It is possible to effectively prevent flooding from occurring on the outlet side of the flow path 40.

  As a result, in the first embodiment, the power generation performance of the fuel cell 10 is well maintained over a long period of time with a simple and economical configuration, particularly without the presence of condensed water in the oxidant gas flow path 40. Thus, it is possible to effectively improve the system efficiency.

  When the circulating coolant temperature becomes higher than the set temperature, the butterfly valve 62 is disposed at the second opening position P2 via the spring members 66a and 66b. Therefore, the cooling medium flow path 44 can maintain a cooling medium flow rate sufficient for cooling, and can cool the entire fuel cell 10 satisfactorily.

  In the first embodiment, the butterfly valve 62 is attached only to the cooling medium supply communication hole 32a. However, the present invention is not limited to this. For example, a butterfly valve (not shown) can also be attached to the cooling medium supply communication hole 30a side, and the flow rate of the cooling medium supplied from the upper side to the lower side of the cooling medium flow path 44 can be adjusted stepwise. Further, a butterfly valve (not shown) may be attached to the cooling medium discharge communication hole 32b instead of the cooling medium supply communication hole 32a.

  Furthermore, in the first embodiment, the two cooling medium supply communication holes 30a and 32a are provided. However, three or more cooling medium supply communication holes are provided, and at least in the cooling medium supply communication hole located at the lowest position. A butterfly valve 62 may be attached. The same applies to the second embodiment described below.

  FIG. 6 is a system explanatory diagram of a fuel cell 80 according to the second embodiment of the present invention. The same components as those of the fuel cell 10 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  A cooling medium flow rate adjusting mechanism 84 is disposed on an end plate 82 (or another plate adjacent to the end plate) constituting the fuel cell 80 corresponding to the cooling medium supply communication hole 32a.

  The cooling medium flow rate adjusting mechanism 84 includes a butterfly valve 62 and a rotary drive source that can adjust the butterfly valve 62 to a desired opening position, for example, a servo motor 86. The servo motor 86 is driven and controlled by the control unit 88, and the control unit 88 controls the operation of the fuel cell 80.

  For example, temperature information from a temperature sensor 90 that detects the temperature of the cooling medium discharged from the cooling medium discharge communication hole 32 b is input to the control unit 88, and the control unit 88 outputs the output voltage of the fuel cell 80. And a function of calculating the power generation output based on the output current.

  In the second embodiment configured as described above, for example, the opening degree of the butterfly valve 62 is adjusted based on the coolant temperature detected by the temperature sensor 90. Specifically, as shown in FIG. 7, when the cooling medium temperature is low, the opening degree of the butterfly valve 62 is adjusted to the first opening degree that is close to the fully closed state, whereby the cooling medium supply communication hole 32a. The cooling medium flow rate supplied to the cooling medium flow path 44 is significantly reduced.

  Then, as the temperature of the cooling medium rises, the opening degree of the butterfly valve 62 is adjusted from the second opening degree to the fully open state, so that the cooling medium flow rate supplied to the cooling medium flow path 44 is increased. Is done.

  Thereby, while preventing condensation of generated water, the cell temperature can be adjusted with high accuracy, and the power generation performance of the fuel cell 80 can be maintained well over a long period of time. Similar effects can be obtained.

  In the second embodiment, as shown in FIG. 8, the opening degree of the butterfly valve 62 can be adjusted according to the power generation output of the fuel cell 80. That is, when the power generation output of the fuel cell 80 is small, the gas flow rate is low and flooding is likely to occur.

  Therefore, when the power generation output is low, the flow rate of the cooling medium supplied to the lower side of the cooling medium flow path 44 can be reduced by adjusting the opening degree of the butterfly valve 62 to the first opening degree. Can be effectively prevented. Thus, the same effect as described above can be obtained by adjusting the opening degree of the butterfly valve 62 based on the power generation output of the fuel cell 80.

  In the second embodiment, the servo motor 86 is used to rotationally control the butterfly valve 62. However, the present invention is not limited to this. For example, a stepping motor may be used. Further, when the opening degree is adjusted by the cooling medium temperature, for example, a bimetal, a thermal expansion body (thermo wax), a shape memory alloy, or the like can be used.

1 is a schematic perspective explanatory view of a fuel cell according to a first embodiment of the present invention. It is a principal part disassembled schematic perspective view of the said fuel cell. FIG. 4 is a schematic perspective explanatory view showing a state in which a cooling medium flow rate adjusting mechanism is mounted on an end plate constituting the fuel cell. It is operation | movement explanatory drawing of a cooling medium flow volume adjustment mechanism. It is adjustment explanatory drawing of the coolant flow rate by the said coolant flow rate adjustment mechanism. It is system explanatory drawing of the fuel cell which concerns on the 2nd Embodiment of this invention. It is explanatory drawing of the opening degree adjustment by cooling-medium temperature. It is explanatory drawing of the opening degree adjustment by an electric power generation output. 2 is an explanatory diagram of a fuel cell according to Patent Document 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 80 ... Fuel cell 12 ... Electrolyte membrane electrode assembly 14, 16 ... Separator 18 ... Unit cell 24a, 24b, 82 ... End plate 26a ... Oxidant gas supply communication hole 26b ... Oxidant gas discharge communication hole 28a ... Fuel Gas supply communication hole 28b ... Fuel gas discharge communication hole 30a, 32a ... Cooling medium supply communication hole 30b, 32b ... Cooling medium discharge communication hole 34 ... Solid polymer electrolyte membrane 36 ... Cathode side electrode 38 ... Anode side electrode 40 ... Oxidizing agent Gas channel 42 ... Fuel gas channel 44 ... Coolant medium channel 46a ... Oxidant gas inlet manifold 46b ... Oxidant gas outlet manifold 48a ... Fuel gas inlet manifold 48b ... Fuel gas outlet manifold 50a ... Coolant inlet manifold 50b ... Cooling Medium outlet manifold 60, 84 ... Cooling medium flow rate adjusting mechanism 62 ... Butterfly Lube 66a, 66b ... spring members 86 ... servomotor 88 ... controller 90 ... Temperature sensor

Claims (3)

An electrolyte membrane / electrode structure provided with a pair of electrodes on both sides of the electrolyte membrane, and a separator are stacked, and a reaction gas passage for supplying a reaction gas along the electrode surface is formed, and the reaction gas passage A cooling medium flow path that crosses the reactive gas flow direction and supplies the cooling medium in a direction along the electrode surface,
The cooling medium flow path communicates with a plurality of cooling medium supply communication holes and a plurality of cooling medium discharge communication holes extending in the stacking direction of the electrolyte membrane / electrode structure and the separator,
The fuel cell is characterized in that a cooling medium flow rate adjusting mechanism is disposed inside the fuel cell corresponding to at least one of the plurality of cooling medium supply communication holes or the plurality of cooling medium discharge communication holes. . The fuel cell according to claim 1, wherein a pair of end plates are disposed at both ends of the electrolyte membrane / electrode structure and the separator in the stacking direction,
The fuel cell, wherein the cooling medium flow rate adjusting mechanism is integrally disposed in at least one of the end plates.   3. The fuel cell according to claim 1, wherein the cooling medium flow rate adjustment mechanism includes a butterfly valve. 4.

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