JP5123824B2 - FUEL CELL STACK AND METHOD OF OPERATING FUEL CELL STACK - Google Patents

Description

The present invention includes a unit cell having a joined body constituted by sandwiching a solid polymer electrolyte membrane between an anode side electrode and a cathode side electrode, and a plurality of the unit cells are stacked to integrally constitute a cell assembly. the method of operating a fuel cell stack and a fuel cell stack you about.

  In general, a polymer electrolyte fuel cell (PEFC) employs an electrolyte membrane made of a polymer ion exchange membrane (cation exchange membrane), and an anode side electrode mainly composed of carbon on each side of the electrolyte membrane. And a unit cell (unit power generation cell) configured by sandwiching a joined body (electrolyte / electrode assembly) composed of a cathode electrode and a separator (bipolar plate), A predetermined number of these unit cells are stacked and used as a fuel cell stack.

  In this type of fuel cell, a fuel gas supplied to the anode side electrode, for example, a gas mainly containing hydrogen (hereinafter, also referred to as a hydrogen-containing gas) is hydrogen ionized on the catalyst electrode, and passes through an electrolyte. It moves to the cathode side electrode side. Electrons generated in the meantime are taken out to an external circuit and used as direct current electric energy. The cathode side electrode is supplied with an oxidant gas, for example, a gas mainly containing oxygen or air (hereinafter also referred to as an oxygen-containing gas). And oxygen react to produce water.

  By the way, in the fuel cell stack, for example, when used for in-vehicle use, a relatively large output is required. For this reason, the structure which sets the dimension of the reaction surface (power generation surface) of a unit cell large, the structure which laminates | stacks many said unit cells, etc. are employ | adopted (refer patent document 1).

JP 2000-30730 A

  However, it has been pointed out that when the size of the unit cell itself is set large, the entire fuel cell stack becomes large and is not suitable for in-vehicle use. Therefore, a fuel cell stack in which a large number of relatively compact unit cells are stacked is usually used. However, as the number of stacked layers increases, temperature distribution tends to occur in the stacking direction, and the electrochemical reaction causes There is a problem that the generated water drainage and the like are deteriorated and the desired power generation performance cannot be obtained.

The present invention has been made to solve this kind of problem, an object with a simple structure, it is possible to effectively improve the power generation performance of each unit cell, to provide a fuel cell stack that Suitable for miniaturization And

Another object of the present invention is to provide a method for operating a fuel cell stack capable of effectively generating power in a unit cell and improving drainage and the like.

In the fuel cell stack according to the present onset bright, with a unit cell having a joint body composed by sandwiching a solid polymer electrolyte membrane between the anode electrode and a cathode electrode are superposed plurality, the unit cells, A reaction gas flow path for flowing at least one reaction gas of a fuel gas or an oxidant gas is provided along the electrode surface, and at least two of the unit cells include cell assemblies having different reaction gas flow path lengths, respectively . said same cell assembly are superimposed plurality. For this reason, it becomes possible to employ | adopt the structure optimal for reaction for every unit cell, and can improve a power generation function effectively. Furthermore, in the unit cell in which the reaction gas channel length is set to be long, a pressure drop of the reaction gas is caused, and the drainage of the produced water can be improved.

At that time, it provided in at least two unit cells, the reactive gas flow channel for flowing at least one reactant gas in the fuel gas or oxidant gas, that have different respective flow path cross-sectional area. Thereby, even if the amount of reaction gas decreases due to the electrochemical reaction, the reaction on the reaction surface of each unit cell is made uniform.

Specifically, each of the flow path cross-sectional area are each channel depth, at least one of the channel width or the channel number is Ru is set by different. By setting the flow path depth shallow, the unit cell can be thinned and the entire cell assembly can be downsized. If the flow path width is set narrow or the number of flow paths is reduced, the contact area between the unit cells increases and the contact resistance can be reduced.

Wherein at least two unit cells, that have different respective reaction gas flow path configuration. For example, by setting one to a linear shape and the other to a meandering shape, a structure optimal for reaction can be adopted for each unit cell.

Furthermore, at least two unit cells each have a different joined body. For example, the joined body on the downstream side in the flow direction of the reaction gas channel is set to have higher heat resistance than the joined body on the upstream side in the flow direction. This is because the joined body on the downstream side in the flow direction has a higher temperature than the joined body on the upstream side in the flow direction. Specifically, the reaction gas channel in the flow direction upstream side of the assembly, while with a fluoride Motomaku, conjugate flows downstream side is provided with a hydrocarbon Motomaku. Flow direction downstream side of the joint body temperature is higher than the bonded body in the flow direction upstream side, by using a hydrocarbon Motomaku having heat resistance, improvement of durability is achieved.

Also, in the cell assembly, reaction gas passages for flowing at least one reactant gas in the fuel gas or oxidizer gas to the plurality of unit cells, and communicates at least a portion in series across each unit cell. Here, at least a part means a case where it is at least a part of a plurality of reaction gas channels and a case where it is at least a part of the reaction gas channels themselves.

  For this reason, the humidity of each unit cell can be made uniform simply by increasing the flow rate of the reaction gas supplied into the cell assembly, and the current density distribution of the plurality of unit cells is made uniform to reduce the concentration overvoltage. It becomes possible to do. In addition, the generated water of each unit cell can be effectively discharged only by increasing the flow rate of the reaction gas supplied into the cell assembly, and the drainage of the entire cell assembly is improved.

Also, the operating method of the fuel cell stack according to the present onset bright, each unit cell constituting a plurality overlapped with cell assemblies, at least two are operated at different conditions. Specifically, with respect to the temperature of the unit cells in the flow direction upstream side of the reaction gas (or one), that has a temperature of the unit cells in the flow direction downstream side (or the other) to a high temperature. Because a large amount of produced water in the flow direction downstream side is generated, by raising the temperature of the unit cell on the downstream side, because drainage is improved enabled.

Furthermore, that with respect to the flow rate of the reaction gas flowing through the unit cell in the flow direction upstream side of the reaction gas (or one), it has a higher flow rate of the reaction gas flowing through the unit cell of the flow direction downstream side (or the other) . Accordingly, it is possible to reliably discharge a large amount of generated water downstream in the flow direction.

Furthermore, the humidity at the reaction gas inlet of the unit cell downstream (or the other) in the flow direction is lower than the humidity at the reaction gas outlet of the unit cell upstream (or one) in the reaction gas flow direction. The For this reason, the generated water is smoothly discharged from the downstream side in the flow direction.

The engagement Ru fuel cell stack to the present invention, together with the cell assembly by superimposing a plurality of unit cells are configured, the unit cell, the fuel gas or the reactive gas stream flowing at least one reactant gas of the oxidizing gas A path is provided along the electrode surface, and at least two of the unit cells have different reaction gas flow path lengths , and each unit cell can adopt an optimum structure for the reaction. The power generation function can be effectively improved.

Further, in the fuel cell stack operation method according to the present invention, each unit cell is operated under different conditions, so that optimum operation conditions are set for each unit cell, and it is easy to improve power generation performance and drainage performance. It becomes feasible.

  FIG. 1 is an exploded perspective view of a main part of a polymer electrolyte cell assembly 10 according to a first embodiment of the present invention, and FIG. 2 is a diagram in which a plurality of sets of the cell assemblies 10 are stacked (stacked). 1 is a schematic perspective view of a fuel cell stack 12 configured.

  As shown in FIG. 1, the cell assembly 10 is configured by overlapping a first unit cell 14 and a second unit cell 16, and the first and second unit cells 14 and 16 include first and second unit cells 14 and 16. Two joined bodies 18 and 20 are provided.

  The first and second assemblies 18 and 20 include solid polymer electrolyte membranes 22a and 22b, and cathode-side electrodes 24a and 24b and anode-side electrodes 26a and 26b disposed with the electrolyte membranes 22a and 22b interposed therebetween. Have. The cathode-side electrodes 24a and 24b and the anode-side electrodes 26a and 26b are configured by bonding a noble metal-based catalyst electrode layer to a base material mainly composed of carbon, and the surface thereof is, for example, a porous layer. A gas diffusion layer made of porous carbon paper or the like is provided.

  As shown in FIGS. 1 and 3, the first separator 28 is disposed on the cathode side electrode 24 a side of the first assembly 18, and the second separator 30 is disposed on the anode side electrode 26 b side of the second assembly 20. In addition, an intermediate separator 32 is disposed between the first and second joined bodies 18 and 20. On the outer surface side of the first and second separators 28 and 30, a thin plate-like wall plate (partition wall member) 34 is provided.

  As shown in FIG. 1, the first and second unit cells 14 are disposed at one end edge on the long side of the first and second joined bodies 18 and 20, the first and second separators 28 and 30, and the intermediate separator 32. , An oxidant gas inlet 36a for passing an oxidant gas (reaction gas) which is an oxygen-containing gas or air, and communicates with each other in the overlapping direction (arrow A direction) of 16, an oxidant gas outlet 36b, A fuel gas intermediate communication hole 38 for allowing a fuel gas (reaction gas) such as a hydrogen-containing gas to pass therethrough is provided.

  The first and second joined bodies 18 and 20, the first and second separators 28 and 30, and the other end edges on the long side of the intermediate separator 32 communicate with each other in the direction of arrow A, and oxidant gas is supplied. An oxidant gas intermediate communication hole 40 for passing, a fuel gas inlet 42a for passing fuel gas, a fuel gas outlet 42b, a cooling medium inlet 44a for passing a cooling medium, and a cooling medium outlet 44b Is provided.

  The first separator 28 is composed of a thin metal plate, and a portion corresponding to the reaction surface (power generation surface) of the first joined body 18 is set to have an uneven shape, for example, a wave shape. As shown in FIGS. 3 and 4, the first separator 28 is provided with a plurality of oxidant gas flow paths (reactive gas flow paths) 46 on the side facing the cathode side electrode 24 a of the first joined body 18, The oxidant gas channel 46 extends linearly in the long side direction (arrow B direction), and both ends thereof communicate with the oxidant gas inlet 36 a and the oxidant gas intermediate communication hole 40.

  As shown in FIGS. 1 and 3, the first separator 28 is provided with a plurality of cooling medium channels 48 on the side facing the one surface of the wall plate 34. The cooling medium flow path 48 extends linearly in the long side direction (arrow B direction), one end communicates with the cooling medium inlet 44a, and the other end side is formed on the wall plate 34, or another It communicates with the cooling medium outlet 44b from the other surface side of the wall plate 34 through a hole 50 which is an intermediate folded portion formed in the member.

  The second separator 30 is configured in substantially the same manner as the first separator 28 described above, and a plurality of fuel gas flow paths (reactive gas flow paths) 52 are provided on the side of the second assembly 20 facing the anode side electrode 26b. The fuel gas channel 52 extends linearly in the long side direction (arrow B direction), and both ends thereof communicate with the fuel gas intermediate communication hole 38 and the fuel gas outlet 42b. The second separator 30 is provided with a plurality of cooling medium channels 54 on the side facing the wall plate 34. The cooling medium channel 54 extends linearly in the long side direction (arrow B direction), and the end communicates with the cooling medium outlet 44b.

  The intermediate separator 32 is configured in substantially the same manner as the first and second separators 28 and 30 described above, and a plurality of fuel gas flow paths (reactive gases) are provided on the side of the first assembly 18 facing the anode side electrode 26a. The fuel gas channel 56 extends linearly in the long side direction (arrow B direction), and both ends thereof communicate with the fuel gas inlet 42a and the fuel gas intermediate communication hole 38. To do.

  As shown in FIG. 3, the intermediate separator 32 is provided with a plurality of oxidant gas flow paths (reaction gas flow paths) 58 on the side facing the cathode side electrode 24b of the second assembly 20, and the oxidant gas. The flow path 58 extends linearly in the long side direction (arrow B direction), and both ends thereof communicate with the oxidant gas intermediate communication hole 40 and the oxidant gas outlet 36b.

  The oxidant gas channels 46 and 58 provided in series in the first and second unit cells 14 and 16 and the fuel gas channels 56 and 52 have different channel cross-sectional areas. As shown in FIG. 3, the outlet side oxidant gas flow path 58 and the fuel gas flow path 52 are set to have a smaller cross-sectional area than the inlet side oxidant gas flow path 46 and the fuel gas flow path 56. Yes.

  As shown in FIG. 2, the cell assembly 10 configured as described above is superposed in the direction of the arrow A as shown in FIG. 2 while being integrally held via a fixing unit (not shown). End plates 62a and 62b are disposed at both ends of the cell assembly 10 in the direction of arrow A via current collecting electrodes 60a and 60b, and the end plates 62a and 62b are tightened by a tie rod or the like (not shown) to thereby form a fuel cell stack. 12 is configured.

  An oxidant gas supply port 64a and an oxidant gas discharge port 64b communicating with the oxidant gas inlet 36a and the oxidant gas outlet 36b are formed at one end edge on the long side of the end plate 62a. At the other end of the long side of the end plate 62a, a fuel gas inlet 42a, a fuel gas outlet 42b, a fuel gas supply port 66a communicating with the cooling medium inlet 44a and the cooling medium outlet 44b, a fuel gas outlet 66b, A medium supply port 68a and a cooling medium discharge port 68b are formed.

  Operations of the fuel cell stack 12 and the cell assembly 10 configured as described above will be described below.

  In the fuel cell stack 12, a fuel gas such as a hydrogen-containing gas is supplied from the fuel gas supply port 66a, and an oxidant gas that is air or an oxygen-containing gas is supplied from the oxidant gas supply port 64a, and further cooled. A cooling medium such as pure water, ethylene glycol, or oil is supplied from the medium supply port 68a. For this reason, in the fuel cell stack 12, the fuel gas, the oxidant gas, and the cooling medium are sequentially supplied to the plurality of sets of cell assemblies 10 superimposed in the direction of arrow A.

  As shown in FIG. 5, the oxidant gas supplied to the oxidant gas inlet 36 a communicating in the direction of arrow A is introduced into a plurality of oxidant gas flow paths 46 provided in the first separator 28. , And moves along the cathode side electrode 24a constituting the first joined body 18. On the other hand, the fuel gas supplied to the fuel gas inlet 42 a is introduced into the plurality of fuel gas flow paths 56 provided in the intermediate separator 32 and moves along the anode side electrode 26 a constituting the first assembly 18. To do. Therefore, in the first joined body 18, the oxidant gas supplied to the cathode side electrode 24a and the fuel gas supplied to the anode side electrode 26a are consumed by an electrochemical reaction in the catalyst layer, and power generation is performed. .

  The oxidant gas partially consumed by the first joined body 18 is introduced from the oxidant gas flow path 46 into the oxidant gas intermediate communication hole 40 and along the oxidant gas intermediate communication hole 40 in the direction of arrow A. After the movement, the gas is introduced into the oxidant gas channel 58 provided in the intermediate separator 32. The oxidant gas moves along the cathode side electrode 24b constituting the second assembly 20 through the oxidant gas flow path 58.

  Similarly, the fuel gas partially consumed by the anode side electrode 26a constituting the first joined body 18 is introduced into the fuel gas intermediate communication hole 38, and then moves in the direction of arrow A to reach the second separator 30. It is introduced into the provided fuel gas flow path 52 and moves along the anode side electrode 26 b constituting the second assembly 20. For this reason, in the 2nd conjugate | zygote 20, oxidant gas and fuel gas are consumed by an electrochemical reaction within a catalyst layer, and electric power generation is performed. The oxidant gas in which oxygen is consumed is discharged to the oxidant gas outlet 36b, and the fuel gas in which hydrogen is consumed is discharged to the fuel gas outlet 42b.

  On the other hand, the cooling medium supplied to the cooling medium inlet 44 a moves along the cooling medium flow path 48 provided in the first separator 28, and then turns back at the hole 50 formed in the wall plate 34. It moves along the cooling medium flow path 54 provided in the separator 30, and is discharged to the cooling medium outlet 44b.

  In this case, in the first embodiment, the oxidant gas channels 46 and 58 and the fuel gas channels 56 and 52 have different channel cross-sectional areas. Specifically, the oxidant gas channel 58 and the fuel gas channel 52 on the outlet side are set to have a smaller channel cross-sectional area than the oxidant gas channel 46 and the fuel gas channel 56 on the inlet side ( (See FIG. 3). As the oxidant gas and the fuel gas move to the outlet side, the oxygen gas and the hydrogen gas are consumed and reduced by the reaction. For this reason, by reducing the cross-sectional areas of the oxidant gas flow path 58 and the fuel gas flow path 52 on the outlet side, the reaction on the reaction surface of the second joined body 20 is made uniform.

  Here, when changing the cross-sectional area of each of the oxidant gas flow paths 46 and 58 and the fuel gas flow paths 56 and 52, the flow path depth, the flow path width, or the number of the flow paths is set. It can be set by changing.

  Specifically, as shown in FIG. 6, the oxidant gas flow path provided in the plate-shaped intermediate separator 32a with respect to the flow path depth of the oxidant gas flow path 46a provided in the plate-shaped first separator 28a. The flow path depth of 58a is set to be shallow, and the fuel gas flow path 52a provided in the plate-shaped second separator 30a has a flow path depth of the fuel gas flow path 56a of the intermediate separator 32a. The flow path depth is set small. Thereby, the thickness of the first and second unit cells 14 and 16 can be reduced, and the entire cell assembly 10 can be easily reduced in size.

  Further, as shown in FIG. 7, in the intermediate separator 32b and the second separator 30b, the flow width of the fuel gas flow path 52b on the outlet side is set smaller than the flow width of the fuel gas flow path 56b on the inlet side. The For this reason, the contact area between the first and second unit cells 14 and 16 is increased, and the contact resistance can be reduced. Although not shown, the same applies to the oxidizing gas channel.

  Further, as shown in FIG. 8, in the plate-like first separator 28c, intermediate separator 32c, and second separator 30c, the number of outlets is larger than the number of inlet-side oxidant gas passages 46c and fuel gas passages 56c. The number of the oxidant gas passages 58c and the fuel gas passages 52c on the side is reduced. As a result, the contact area between the first and second unit cells 14 and 16 can be effectively increased as described above.

  Furthermore, in order to improve drainage in the first and second unit cells 14 and 16, the gas flow path length in the second unit cell 16 on the outlet side is set to the value of the first unit cell 14 on the inlet side. What is necessary is just to set longer than the gas flow path length. This is because the amount of generated water increases toward the outlet side, and by increasing the length of the gas flow path on the outlet side, a pressure drop can be caused and the drainage of the generated water can be improved.

  Specifically, as shown in FIG. 9, for example, the intermediate separator 32 is provided with a linear fuel gas passage 56, while the second separator 30d is provided with a meandering fuel gas passage 52d. . Therefore, the gas flow path length of the fuel gas flow path 52d on the outlet side is effectively made longer than the gas flow path length of the fuel gas flow path 56 on the inlet side. In place of the meandering fuel gas passage 52d, a bent or curved fuel gas passage may be employed.

  In the first embodiment, a plurality of cell assemblies 10, for example, two unit cells 14 and 16, are integrally formed, so that each unit cell is handled by handling as the cell assembly 10. Compared to the conventional configuration, the workability when assembling the fuel cell stack 12 is effectively simplified.

  Further, in the first embodiment, the cell assembly 10 is integrally configured by the first and second unit cells 14, 16, and the oxidant gas flow path 46 extends across the first and second unit cells 14, 16. 58 and the fuel gas flow paths 56 and 52 communicate at least partially in series via the oxidant gas intermediate communication hole 40 and the fuel gas intermediate communication hole 38. As a result, the oxidant gas flow path 46 and the fuel gas flow path 56 on the inlet side are supplied with the oxidant gas and fuel gas in amounts necessary for the reaction of the entire first and second unit cells 14 and 16, respectively. The oxidant gas flow path 46 and the fuel gas flow path 56 have a flow rate twice that of a normal unit cell.

  Therefore, in particular, drainage performance in the oxidant gas flow paths 46 and 58 in which the generated water is generated can be improved, and the humidity in the first and second unit cells 14 and 16 can be made uniform. For this reason, it is possible to obtain an effect that the density overvoltage can be reduced by making the current density distribution of the first and second unit cells 14 and 16 uniform.

  Further, since the oxidant gas flow paths 46 and 58 and the fuel gas flow paths 56 and 52 communicate in series across the first and second unit cells 14 and 16, they are supplied to the oxidant gas inlet 36a and the fuel gas inlet 42a. The flow rates of the oxidizing gas and the fuel gas increase as compared with the conventional unit cell. Therefore, the generated water generated in the first and second unit cells 14 and 16 can be effectively discharged, and the drainage of the entire cell assembly 10 is greatly improved.

  Next, an operation method according to the present invention will be described using the cell assembly 10 and the fuel cell stack 12 described above. The basic operation has been described in the operations of the cell assembly 10 and the fuel cell stack 12, and will be briefly described below.

  In the operation method of the present invention, the first and second unit cells 14 and 16 are operated under mutually different conditions. Specifically, the following first to fourth methods are employed.

  First, in the first method, the temperature of the second unit cell 16 on the downstream side is set higher than the temperature of the first unit cell 14 on the upstream side. For example, in the case of the cathode side electrodes 24a and 24b, as shown in FIG. 10, by increasing the temperature in the gas flow path on the second unit cell 16 side compared to the first unit cell 14 side, The relative humidity in the gas flow paths of the second unit cells 14 and 16 is as shown in FIG. This is because the change in humidity is reduced in the first unit cell 14 because the oxidant gas for two cells is supplied, whereas the relative humidity is reduced in the second unit cell 16 due to the cell temperature being increased. .

  Thereby, the relative humidity in the first and second unit cells 14 and 16 can be made uniform, the ionic conductivity of the electrolyte membranes 22a and 22b can be improved, and the concentration overvoltage can be reduced.

  In the second method of the present invention, the flow rates of the oxidant gas and the fuel gas flowing through the second unit cell 16 are made higher than the flow rates of the oxidant gas and the fuel gas flowing through the first unit cell 14. ing. In particular, a larger amount of generated water is generated toward the outlet side of the oxidant gas, and by setting the flow rate of the oxidant gas flowing through the second unit cell 16 on the downstream side in the flow direction, the generated water is discharged. There is an advantage that the performance is improved.

  Furthermore, in the third method of the present invention, the oxidant gas that is the reaction gas inlet of the second unit cell 16 with respect to the humidity in the oxidant gas intermediate communication hole 40 that is the reaction gas outlet of the first unit cell 14. The humidity at the inlet 36a is lowered (see the solid line in FIG. 11).

  Furthermore, in the fourth method of the present invention, the utilization rate of the reaction gas in the second unit cell 16 is made higher than the utilization rate of the reaction gas in the first unit cell 14. For this reason, the utilization factor of the cell assembly 10 as a whole is improved, and the amount of reaction gas used can be effectively reduced.

  FIG. 12 is an exploded perspective view of main parts of a cell assembly 80 according to the second embodiment of the present invention. Note that the same components as those of the cell assembly 10 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. The same applies to the third and subsequent embodiments described below.

  The cell assembly 80 includes first and second joined bodies 82 and 84. The first joined body 82 has a fluorine-based electrolyte membrane 86, and the second joined body 84 has a hydrocarbon-based electrolyte membrane 88.

  In the second embodiment configured as described above, the second joined body 84 on the downstream side in the flow direction of the reaction gas has a higher temperature than the first joined body 82 on the upstream side in the flow direction. A hydrocarbon electrolyte membrane 88 having heat resistance is provided at 84. Thereby, the durability of the second bonded body 84 is improved, and the second bonded body 84 can be used over a long period of time, which is economical.

  FIG. 13 is an exploded perspective view of a main part of a polymer electrolyte cell assembly 100 according to the third embodiment of the present invention.

  The cell assembly 100 is configured by superposing first and second unit cells 102 and 104 in the direction of arrow A. The first and second unit cells 102 and 104 include first and second joined bodies 106 and 108, and the first and second joined bodies 106 and 108 include the first separator 110, the second separator 112, and the middle. It is sandwiched between separators 114.

  At one end edge on the long side of the first and second unit cells 102, 104, an oxidant gas inlet 36a, a fuel gas outlet 42b, and a cooling medium inlet 44a are provided in communication with each other in the direction of arrow A. Similarly, an oxidant gas outlet 36b, a fuel gas inlet 42a, and a cooling medium outlet 44b are provided at the other end of the long side in communication with each other in the direction of arrow A.

  A plurality of cooling medium channels 48 are provided on one surface of the first separator 110. One end of the cooling medium channel 48 communicates with the cooling medium inlet 44a and the other end communicates with the cooling medium outlet 44b, and extends linearly in the arrow B direction.

  On the other surface of the first separator 110, as shown in FIG. 14, a plurality of fuel gas passages 56 are provided in a straight line in the direction of arrow B, and the fuel gas passages 56 are arranged at the fuel gas inlet. Both ends communicate with 42a and the fuel gas outlet 42b. The fuel gas channel 56 is configured, for example, such that the groove depth becomes shallower toward the fuel gas outlet 42b.

  In the second separator 112, a plurality of oxidant gas flow paths 58 are linearly provided in the direction of arrow B on the surface side facing the cathode side electrode 24 b constituting the second joined body 108. The oxidant gas flow path 58 has both ends communicating with the oxidant gas inlet 36a and the oxidant gas outlet 36b.

  The intermediate separator 114 is provided with an oxidant gas flow path 46 in a straight line on the surface facing the cathode side electrode 24a constituting the first assembly 106, and both ends of the oxidant gas flow path 46 are oxidant gas. Narrowed portions 116a and 116b are formed at portions communicating with the inlet 36a and the oxidizing gas outlet 36b. A fuel gas flow path 52 is formed on the surface side of the intermediate separator 114 facing the anode side electrode 26b constituting the second assembly 108, as in the first separator 110 (see FIG. 15).

  In the cell assembly 100 configured as described above, the cooling medium flow path 48 is provided on the surface of the second separator 112 opposite to the oxidant gas flow path 58. For this reason, the oxidant gas flow path 58 of the second separator 112 is cooled via the cooling medium and becomes the low temperature side, while the oxidant gas flow path 46 of the intermediate separator 114 is hardly cooled and becomes the high temperature side, Different temperature environments occur between the second unit cells 102 and 104. At this time, in the second separator 112 on the low temperature side, generated water exists in the oxidant gas flow path 58, and water accumulates in the flow path, the diffusion layer, or the catalyst layer, and the oxidant gas flow path 58 may be blocked. There is.

  Therefore, in the third embodiment, a structure is adopted in which the humidity is made uniform by increasing the flow rate in the oxidant gas flow path 58 provided in the second separator 112 and the generated water drainage is improved by increasing the flow velocity. doing. That is, throttle portions 116a and 116b are provided at portions communicating with the oxidant gas inlet 36a and the oxidant gas outlet 36b of the oxidant gas flow path 46 provided in the high temperature side intermediate separator 114 (see FIG. 13). ). Thereby, the oxidant gas flow rate in the oxidant gas flow path 58 of the second separator 112 is increased as compared with the oxidant gas flow rate in the oxidant gas flow path 46 of the intermediate separator 114.

  For this reason, in the third embodiment, the generated water is reliably discharged from the second separator 112 on the low temperature side, the humidity is made uniform, and the flow rate and flow rate of the oxidant gas flowing through the intermediate separator 114 on the high temperature side are By decreasing, it is possible to prevent the first joined body 106 from being dried.

  In the third embodiment, the constricted portions 116a and 116b are provided on both end sides of the high-temperature side oxidant gas flow path 46. Instead, grooves in the low-temperature side oxidant gas flow path 58 are provided. By making the depth shallower than the groove depth of the oxidizing gas channel 46 on the high temperature side, it is possible to easily cope with this.

  FIG. 16 is an exploded perspective view of a main part of a polymer electrolyte cell assembly 120 according to the fourth embodiment of the present invention. Note that the same components as those of the cell assembly 100 according to the third embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The cell assembly 120 is configured by stacking a first unit cell 122, a second unit cell 124, and a third unit cell 126 in the arrow A direction. The first to third unit cells 122, 124, and 126 include first to third assemblies 106, 108, and 128, and the first to third assemblies 106, 108, and 128 include the first separator 110, The two separators 112 and the first and second intermediate separators 114a and 114b are sandwiched.

  In the cell assembly 120, different temperature environments are generated in the first to third unit cells 122, 124 and 126, respectively, and in particular, the second joined body 108 is hotter than the first and third joined bodies 106 and 128. It is easy to become.

  Therefore, the first and third bonded bodies 106 and 128 having a relatively low temperature include a fluorine-based electrolyte membrane 86 that can obtain stable performance in a low temperature range, while the second bonded body 108 having a relatively high temperature is a high temperature. Hydrocarbon electrolyte membrane 88 that can withstand Furthermore, since the humidity is high in the first and third joined bodies 106 and 128, a catalyst layer and a diffusion layer having excellent drainage are used, while in the second joined body 108, the humidity is low, Use a diffusion layer with water retention.

  In the cell stack 120 configured as described above, by using different types of the first to third joined bodies 106, 108, and 128, it is possible to improve the performance corresponding to different temperature environments. can get.

  FIG. 17 is an exploded perspective view of main parts of a polymer electrolyte cell assembly 140 according to the fifth embodiment of the present invention.

  The cell assembly 140 is configured by superposing first and second unit cells 142 and 144, and the first and second unit cells 142 and 144 include first and second assemblies 146 and 148. The first and second joined bodies 146 and 148 are sandwiched between the first and second separators 150 and 152 and the first and second intermediate separators 154 and 156, and the first and second intermediate separators 154 and 156 are sandwiched between the first and second separators 154 and 156. A flat plate rectifying plate 158 is interposed therebetween.

  A fuel gas inlet 42 a, an oxidant gas intermediate communication hole 40, and a fuel gas outlet 42 b are provided at one end edge of the long side of the cell assembly 140 in the direction of arrow A, and the long side of the cell assembly 140 An oxidant gas inlet 36a, a cooling medium inlet 44a, a fuel gas intermediate communication hole 38, a cooling medium outlet 44b, and an oxidant gas outlet 36b are provided in the other end edge on the side in the direction of arrow A.

  A cooling medium flow path 54 is linearly provided on the surfaces of the first and second intermediate separators 154 and 156 facing the rectifying plate 158, and in the first intermediate separator 154, the cooling medium inlet 44a One end of the cooling medium flow path 54 communicates with the other end of the cooling medium flow path 54 by a rectifying plate 158 and communicates with the cooling medium flow path 54 provided in the second intermediate separator 156. The cooling medium channel 54 communicates with the cooling medium outlet 44 b of the second intermediate separator 156.

  In the cell assembly 140 configured as described above, the oxidant gas, the fuel gas, and the cooling medium are sent to the first and second unit cells 142 and 144 in series along the flow direction shown in FIG. At that time, a cooling medium flow path 54 is formed between the first and second unit cells 142 and 144 via a rectifying plate 158. Thereby, in particular, it is possible to reliably prevent the temperature from rising excessively inside the cell assembly 140.

  FIG. 19 is an exploded perspective view of main parts of a polymer electrolyte cell assembly 160 according to the sixth embodiment of the present invention. Note that the same components as those of the cell assembly 140 according to the fifth embodiment shown in FIG. 17 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The cell assembly 160 is configured by overlapping the first and second unit cells 162 and 164 in the direction of arrow A, and the oxidant gas intermediate communication hole 40 is not provided. Therefore, in the cell assembly 160, as shown in FIG. 20, while the fuel gas flows along the fuel gas flow paths 56 and 52 that are communicated in series from the first unit cell 162 to the second unit cell 164, Oxidant gas is individually flowed to the first and second unit cells 162 and 164 via the oxidant gas flow paths 46 and 58, that is, in parallel.

  Thus, since the low viscosity fuel gas flows along the fuel gas flow paths 56 and 52 connected in series, the flow length is lengthened and sufficient pressure loss can be provided. There is an advantage that the generated water from the electrodes 26a and 26b can be effectively discharged.

It is a principal part disassembled perspective view of the polymer electrolyte cell assembly which concerns on the 1st Embodiment of this invention. It is a schematic perspective view of a fuel cell stack. It is a partial cross section explanatory view of the cell assembly. It is a front view of the 1st separator which comprises the said cell assembly. 3 is a flow diagram within the cell assembly. It is explanatory drawing at the time of setting a channel cross-sectional area with different channel depths. It is explanatory drawing at the time of setting the said flow-path cross-sectional area by varying a flow-path width. It is explanatory drawing at the time of setting the said flow-path cross-sectional area by varying the number of flow paths. It is a disassembled perspective explanatory drawing of the said cell assembly which changed the flow path length. It is explanatory drawing of the cathode temperature in a 1st and 2nd unit cell. It is explanatory drawing of the cathode relative humidity in the said 1st and 2nd unit cell. It is a principal part disassembled perspective view of the polymer electrolyte cell assembly which concerns on the 2nd Embodiment of this invention. It is a principal part disassembled perspective view of the polymer electrolyte cell assembly which concerns on the 3rd Embodiment of this invention. It is a front view of the 1st separator which comprises the said cell assembly. It is a flowchart of the cell assembly which concerns on the said 3rd Embodiment. It is a principal part disassembled perspective view of the polymer electrolyte cell assembly which concerns on the 4th Embodiment of this invention. It is a principal part disassembled perspective view of the polymer electrolyte cell assembly which concerns on the 5th Embodiment of this invention. 10 is a flowchart of the cell assembly according to the fifth embodiment. It is a principal part disassembled perspective view of the polymer electrolyte cell assembly which concerns on the 6th Embodiment of this invention. 10 is a flowchart of the cell assembly according to the sixth embodiment.

Explanation of symbols

10, 80, 100, 120, 140, 160 ... cell assembly 12 ... fuel cell stack 14, 16, 102, 104, 122, 124, 126, 142, 144, 162, 164 ... unit cell 18, 20, 82, 84 106, 108, 128, 146, 148 ... 22a, 22b, 86, 88 ... electrolyte membranes 24a, 24b ... cathode side electrodes 26a, 26b ... anode side electrodes 28, 28a-28c, 30, 30a-30d, 110 , 112, 150, 152 ... separators 32, 32a to 32c, 114, 154, 156 ... intermediate separator 36a ... oxidant gas inlet 36b ... oxidant gas outlet 38 ... fuel gas intermediate communication hole 40 ... oxidant gas intermediate communication hole 42a ... fuel gas inlet 42b ... fuel gas outlet 44a ... cooling medium inlet 44b ... cooling medium outlet 46 46a-46c, 58, 58a-58c ... Oxidant gas channel 48, 54 ... Cooling medium channel 50 ... Hole 52, 52a-52d, 56, 56a-56c ... Fuel gas channel 64a ... Oxidant gas supply port 64b ... Oxidant gas discharge ports 116a, 116b ... throttle part 158 ... current plate

Claims (14)

A plurality of unit cells having a joined body formed by sandwiching a solid polymer electrolyte membrane between an anode side electrode and a cathode side electrode are stacked, and the unit cell is composed of at least one of a fuel gas and an oxidant gas. A reaction gas flow path for flowing a reaction gas is provided along the electrode surface, and at least two of the unit cells include cell assemblies having different reaction gas flow path lengths, respectively.
A fuel cell stack, wherein a plurality of the same cell assemblies are stacked.   2. The fuel cell stack according to claim 1, wherein the reaction gas flow path cross-sectional areas of at least two of the unit cells are set by different at least one of a flow path depth, a flow path width, and the number of flow paths, respectively. A fuel cell stack characterized by   2. The fuel cell stack according to claim 1, wherein at least two of the unit cells have different reaction gas flow path shapes. 3.   2. The fuel cell stack according to claim 1, wherein at least two of the unit cells include different assemblies. 3.   5. The fuel cell stack according to claim 4, wherein the joined body on the downstream side in the flow direction of the reaction gas passage is set to have higher heat resistance than the joined body on the upstream side in the flow direction. . The fuel cell stack according to claim 5, wherein the low-temperature bonded body includes a fluorine film,
The fuel cell stack, wherein the high-temperature joined body includes a hydrocarbon film.   7. The fuel cell stack according to claim 1, wherein in the cell assembly, a reaction gas flow path for flowing at least one reaction gas of a fuel gas or an oxidant gas to the plurality of unit cells is provided. A fuel cell stack, wherein at least a part of the fuel cell stack communicates in series across each unit cell. Set in the fuel cell stack according to claim 1, the reaction gas flow path length of the unit cell of the exit side of the reaction gas is greater than the reaction gas flow path length of the unit cell of the incoming port side of the reaction gas A fuel cell stack. A plurality of unit cells having a joined body formed by sandwiching a solid polymer electrolyte membrane between an anode side electrode and a cathode side electrode are stacked, and the unit cell is composed of at least one of a fuel gas and an oxidant gas. A reaction gas flow path for supplying a reaction gas is provided along the electrode surface, and at least two of the unit cells include cell assemblies having different reaction gas flow path lengths, and a plurality of the same cell assemblies are stacked. A fuel cell stack operating method for operating a fuel cell stack comprising:
The method of operating a fuel cell stack, wherein at least two unit cells are operated under different conditions.   10. The operation method according to claim 9, wherein the temperature of the other unit cell is set higher than the temperature of the one unit cell.   10. The operation method according to claim 9, wherein the temperature of the reaction gas inlet of the other unit cell is increased with respect to the temperature of the reaction gas outlet of the one unit cell, thereby increasing the temperature of the reaction gas outlet of the one unit cell. The fuel cell stack operating method is characterized in that the humidity at the reaction gas inlet of the other unit cell is lowered with respect to the humidity of the other unit cell. A plurality of unit cells each having a joined body formed by sandwiching a solid polymer electrolyte membrane between an anode side electrode and a cathode side electrode, and the unit cell is a reaction gas of at least one of a fuel gas and an oxidant gas. And at least two of the unit cells have different reaction gas channel lengths, and the plurality of reaction gas channels have at least a portion extending over each unit cell. A fuel cell stack operating method for operating a fuel cell stack comprising a plurality of cell assemblies that are connected in series, and wherein the same cell assembly is stacked.
The method of operating a fuel cell stack, wherein at least two unit cells are operated under different conditions. 13. The operation method according to claim 12 , wherein the temperature of the unit cell downstream in the flow direction is set higher than the temperature of the unit cell upstream in the flow direction of the reaction gas. . 13. The operation method according to claim 12 , wherein the temperature of the reaction gas inlet of the unit cell downstream in the flow direction is made higher than the temperature of the reaction gas outlet of the unit cell upstream in the flow direction of the reaction gas, Operation of a fuel cell stack characterized by lowering the humidity at the reaction gas inlet of the unit cell downstream in the flow direction relative to the humidity at the reaction gas outlet of the unit cell upstream in the flow direction of the reaction gas Method.

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