JP5115070B2 - Fuel cell - Google Patents

Description

  The present invention relates to a fuel cell.

  Conventionally, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2005-353303, a fuel cell is known in which fuel gas is retained in an anode during normal power generation, and the anode is periodically purged. According to this conventional technique, the fuel gas can be efficiently used by generating power while retaining the fuel gas in the anode.

  Impurities such as nitrogen and moisture accumulate in the gas flow path on the anode side of the fuel cell as the operation time elapses. When purging inside the anode to prevent such accumulation of impurities, if the purge gas contains fuel gas, the fuel utilization efficiency is reduced. Therefore, in the above conventional technique, a nitrogen adsorbing member is provided on the downstream side of the gas flow path of the anode, and the fuel gas is effectively utilized while selectively removing nitrogen as an impurity.

JP 2005-353303 A JP 2006-127770 A JP 9-31167 A JP-A-2005-353569 JP 2005-243477 A JP 2006-164762 A JP 2006-216426 A

  In the above conventional technique, nitrogen is collected at the most downstream side of the gas flow path on the anode side. In such a case, depending on the timing of nitrogen removal, the amount of nitrogen becomes excessive, leading to a decrease in power generation reaction, or a special member for removing nitrogen is required. As a result, there is a risk that the control content must be complicated in order to accurately perform the nitrogen removal timing, or that the addition of a dedicated nitrogen removal member may lead to a complicated structure.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a fuel cell capable of generating power while preventing a decrease in power generation performance due to impurities with a simple configuration. To do.

In order to achieve the above object, a first invention is a fuel cell,
Catalyst layer is formed on both surfaces of the electrolyte membrane, supplied with fuel gas containing hydrogen to the anode catalyst layer on one surface side of the both sides of the catalyst layer, the cathode of the other surface side of the both sides of the catalyst layer A power generator for generating electricity by receiving supply of oxidizing gas containing oxygen to the catalyst layer;
It is arranged so as to overlap the anode catalyst layer and extends along a gas inlet into which the fuel gas flows and a surface facing the catalyst layer on the one surface side, the downstream side terminates in the surface, and the upstream side A gas supply member comprising a plurality of groove flow paths that merge with the gas inlet;
A fuel cell system having a fuel cell Ru provided with,
The gas supply member includes a current collector plate disposed to overlap the anode catalyst layer,
The groove channel is formed on a surface of the current collector plate facing the catalyst layer;
The plurality of groove flow paths merge in the plane of the gas supply member to form a branching branch in the plane;
The downstream end of each of the plurality of groove channels is disposed over the entire area of the gas supply member facing the anode catalyst layer and overlapping the anode catalyst layer,
The groove channel is formed such that the channel cross-sectional area in the flow direction of the fuel gas decreases toward the downstream side when viewed from the gas inlet,
The plurality of groove channels are
A plurality of main groove passages extending from a branch portion provided in the vicinity of the center of the current collector plate in the plane and arranged radially around the branch portion;
A plurality of branches are formed from each of the plurality of main groove flow paths, and the downstream end portions of the gas supply members face the anode catalyst layer over the entire region overlapping the anode catalyst layer. An arranged branch channel,
Including
The plurality of main groove channels are
A plurality of first main groove channels having the branch channel;
A second main groove channel provided between the plurality of first main groove channels and not having the branch channel;
Including
The gas supply member does not have an exhaust passage for exhausting the fuel off gas from the catalyst layer,
A fuel tank communicating with the gas inlet of the gas supply member;
A fuel cell system characterized by performing a dead-end operation in which power generation is continuously performed in a state where the partial pressure of the impurity on the anode catalyst layer side is balanced with the partial pressure of the impurity on the cathode catalyst layer side.

The second invention is the first invention, and
The fuel cell system according to claim 1, wherein the first main groove flow paths and the second main groove flow paths are alternately arranged.

According to the first invention, it is possible to generate power by stopping the fuel gas in the anode of the fuel cell while branching and flowing the fuel gas flowing in from the gas inlet into the plurality of groove flow paths. The voltage drop due to the impurity is caused by the local concentration of the impurity in the anode surface of the fuel cell. According to the first aspect of the invention, since the fuel gas branches and flows into the plurality of groove channels, the impurity in the groove channel is dispersed in the plurality of groove channels, so that the impurity is concentrated in one place. It is possible to avoid the situation of being concentrated. This makes it possible to alleviate the concentration of impurities by devising the structure of the groove channel formed in the current collector plate, and with a simple configuration that does not require the addition of components or complicated control operations, the power generation performance resulting from the impurities A decrease can be prevented.
In addition, by devising the structure of the current collector plate, it is possible to prevent a decrease in power generation performance due to impurities with a simple configuration that does not require the addition of components or complicated control operations.
In addition, since the plurality of groove flow paths form grooves that extend in a branched manner in the plane of the fuel cell, the fuel gas can be introduced throughout the entire plane simply by injecting the fuel gas from one gas inlet. Can be supplied in a well-balanced manner.
Further, the downstream end portion of the groove channel, which is the portion having the highest impurity concentration, is dispersed in a well-balanced manner in the plane of the fuel cell. When an impurity concentration gradient occurs in the plane of the fuel cell, diffusion occurs such that the impurity concentration gradient is smoothed. Such concentration gradient can be advanced efficiently, and concentration smoothing can be promptly advanced.
further

According to the second aspect of the present invention, hydrogen can be supplied in a more balanced manner and impurity concentration can be more effectively suppressed.

Embodiment 1 FIG.
[Configuration of Embodiment 1]
The fuel cell of Embodiment 1 has a membrane electrode assembly in which electrode catalyst layers are laminated on both surfaces of an electrolyte membrane. A gas diffusion layer and a current collector are sequentially positioned so as to sandwich the membrane electrode assembly, and one surface side of the membrane electrode assembly functions as an anode and the other surface side functions as a cathode. Many configurations of the membrane electrode assembly and the gas diffusion layer have already been disclosed and are not new configurations, and thus detailed description thereof is omitted. Hereinafter, the configuration of the anode-side current collector plate, which is a feature of the fuel cell of Embodiment 1, will be described.

  FIG. 1 is a diagram showing a configuration of a current collector plate 10 provided on the anode side of the fuel cell of the first embodiment. FIG. 1 shows a surface of the current collector plate 10 facing the anode side. That is, the current collector plate 10 and the membrane electrode assembly are laminated so that the surface shown in FIG. 1 faces the structure on the anode side of the membrane electrode assembly.

  Lines denoted by reference numerals 12, 14, 16, and 18 in FIG. 1 indicate groove channels formed in the current collector plate 10, respectively. As shown in FIG. 1, the groove flow paths 12, 14, 16, and 18 are grooves formed to extend in the surface direction over the entire surface of the current collector plate 10. Note that the cross-sectional area of the groove channel viewed in the gas flow direction is constant in the first embodiment. The groove channels 12, 14, 16, and 18 can be formed by, for example, cutting or pressing.

  A plurality of groove flow paths 14 branch from the groove flow path 12, and the groove flow paths 14 extend in the plane of the current collector plate 10 and further branch to the groove flow paths 16. A plurality of groove channels 18 are further branched from the groove channel 16. Here, the “groove flow path” means a single continuous groove extending in the plane of the current collector plate 10.

  That is, in FIG. 1, three groove channels 18 are connected (joined) to each groove channel 16 to form a groove channel group. And it can be said that this groove channel group is connected (joined) to one groove channel 14 by five. In other words, six groove channels 14 branch from the groove channel 12, five groove channels 16 branch from each groove channel 14, and three groove channels 18 from each groove channel 16. Can be said to be branched.

  The groove channel 18 extends partway in the plane of the current collector plate 10 and has a terminal end. That is, the groove channel 18 is formed such that its downstream end is dead end in the plane. As a result, as shown in FIG. 1, the groove flow paths 12, 14, 16, and 18 are integrated to form a groove having a number of dead ends in the surface.

  The current collector plate 10 is provided with a hydrogen inlet 20 that opens toward a surface facing the left side of FIG. The hydrogen inlet 20 is connected to a fuel tank (not shown) when generating power. The groove channel 12 extends to the lower left part of the current collector plate 10 and is connected to the hydrogen inlet 20.

  The fuel cell of Embodiment 1 has a cathode structure (not shown). Similarly to the anode, an electrode catalyst layer, a gas diffusion layer, and a current collector plate are located on the cathode. A gas flow path for circulating air is formed in the cathode current collector plate. In the fuel cell of this embodiment, the cathode is an open system, as in various conventionally known fuel cells.

  That is, the cathode is provided with an air inlet and outlet, and air is supplied from the cathode gas flow path to the gas diffusion layer and the electrode catalyst layer in the process of air flowing from the inlet to the outlet. It has become. Since the specific structure of such an open cathode is the same as various structures already known, detailed description thereof is omitted.

  At the time of power generation, a fuel gas containing hydrogen flows into the groove channel 12 from the hydrogen inlet 20 and then flows into the groove channels 14, 16, and 18. The fuel gas diffuses into the gas diffusion layer and reaches the electrode catalyst layer in the course of flowing through the groove channel. Hydrogen arrives at the electrode catalyst layer on the anode side and oxygen in the electrode catalyst layer on the cathode side causes an electrochemical reaction to generate electric power.

  For example, when the nitrogen partial pressure rises to some extent on the anode side, the nitrogen partial pressures of the anode and the cathode become equal, and the nitrogen partial pressure on the anode side no longer rises. The same applies to gases other than nitrogen. The fuel cell according to the present embodiment uses this point to generate power in a state where the nitrogen partial pressure is balanced. At this time, the pressure of the anode during power generation is kept higher than the nitrogen partial pressure at the cathode.

[Effect of non-reactive gas pool on power generation]
The power generation of the fuel cell is performed by causing an electrochemical reaction between hydrogen at the anode and oxygen in the air at the cathode via the electrolyte membrane. In a fuel cell that generates power while retaining hydrogen in the anode, hydrogen is continuously supplied in accordance with hydrogen consumption by power generation. Thus, during power generation, hydrogen continuously flows from the hydrogen supply port into the anode.

  The electrolyte membrane has a property of transmitting gas. For this reason, during power generation, oxygen in the cathode air is consumed for power generation, and impurities that do not participate in the power generation reaction such as nitrogen and water vapor pass through the electrolyte membrane from the cathode and move to the anode. Yes. This impurity is swept down downstream as hydrogen flows into the anode.

  FIG. 2 is a schematic diagram for explaining a phenomenon in which impurities are swept away and concentrated. In addition to nitrogen, air contains impurities such as water vapor and carbon dioxide that are not used for power generation, but their concentrations in the air are extremely small compared to nitrogen. We will focus on and describe. However, it does not mean that substances other than nitrogen are excluded from the impurity assumed by the present invention.

  For example, when the fuel gas flows in the S-shaped channel as shown in FIG. 2 along the direction of the arrow, the impurity in the gas channel is pushed downstream by the fuel gas, and nitrogen is concentrated from the downstream side. (The hatched area 30 indicates the nitrogen enriched area). If the impurity is excessively concentrated, the concentrated region becomes a power generation impossible region, which causes various adverse effects such as a decrease in power generation performance due to a voltage drop and an undesirable effect on the internal structure (specifically, the catalyst layer). .

[Operation and Effect of Embodiment 1]
On the other hand, in Embodiment 1, since nitrogen present in the anode is distributed to each groove channel branched in the anode surface, the impurity is transferred into the anode surface through each groove channel, Concentration of nitrogen in one place is prevented. Nitrogen dispersed in the anode surface by each groove channel is further dispersed in the surface by diffusion or the like in the gas diffusion layer. Thereafter, as described above, nitrogen returns to the cathode through the electrolyte membrane and balances in relation to the nitrogen partial pressure difference with the cathode. Thus, according to this embodiment, a voltage drop due to impurities such as nitrogen can be prevented by devising the structure of the groove channel of the current collector plate 10. Therefore, there is an advantage that the addition of components and complicated control operations are not essential.

  In the present embodiment, the groove channels 12, 14, 16, and 18 form continuous grooves so as to be branched in a large number in the anode surface. According to such a configuration, it is possible to supply hydrogen in a well-balanced manner throughout the anode surface only by flowing hydrogen from one hydrogen inlet 20. In addition, it is easier to manufacture as compared to a method of three-dimensionally providing through holes.

  Moreover, in this embodiment, the downstream end part of the groove flow path 18 is disperse | distributed and located over the whole anode surface. When a concentration gradient is generated in the anode plane, gas diffusion occurs such that the nitrogen concentration gradient is smoothed in a layer inside the anode such as a gas diffusion layer. According to the present embodiment, the downstream end portion of the groove channel 18 that is the portion having the highest nitrogen concentration is distributed in a balanced manner in many regions. Therefore, such a concentration gradient can be efficiently advanced to smooth the concentration. Can be advanced promptly.

  Further, the nitrogen existing in the groove channel is diffused from the downstream side toward the upstream side (that is, from the groove channel 18 to the hydrogen inlet 20 through the groove channels 16, 14, 12). ) Try to move. Then, the slower the hydrogen flow rate in the groove channel, the more nitrogen diffuses upstream of the groove channel. In this embodiment, the channel cross-sectional areas of the groove channels 12, 14, 16, 18 are made constant. As a result, hydrogen is consumed in power generation in the process of flowing through the inside of the groove channel, and as a result, the flow rate of hydrogen is reduced. Therefore, it is possible to suppress the concentration of nitrogen by suppressing the flow rate of hydrogen and promoting the concentration diffusion of nitrogen.

In the first embodiment described above, a membrane electrode assembly (not shown) is used as the “power generator” in the first invention, and the current collector plate 10 is used as the “gas supply member” in the first invention. Reference numeral 18 corresponds to the “groove channel” in the first invention, and the hydrogen inlet 20 corresponds to the “gas inlet” in the first invention. The current collecting plate 10 corresponds to the “current collecting plate” in the first invention. A branched groove formed by joining a plurality of groove flow paths 18 to the groove flow paths 16, 14, 12 in the surface of the current collector plate 10 is “in the plane” of the first invention. This corresponds to a “branching groove”.

[Modification of Embodiment 1]
The groove channel pattern according to the present invention is not limited to the pattern of the first embodiment. For example, each groove flow path does not necessarily extend linearly in the surface of the current collector plate 10 as shown in the drawing, and may draw a curve in the surface of the current collector plate 10. In FIG. 1, the groove channel 18 may not be provided, and the downstream side may be terminated up to the groove channel 16. Alternatively, only the groove channels 12 and 14 may be provided, and the downstream end of the groove channel 14 may be a dead end. This is because the hydrogen flowing in from the hydrogen inlet 20 can be branched and flowed by these configurations, and the nitrogen concentration can be dispersed throughout.

  For example, as a modification, variations of the groove flow paths as shown in FIGS. The current collecting plate 50 in FIG. 3 is obtained by changing the channel cross-sectional area at each position in the groove channel having the same pattern as that of the first embodiment. In the current collector plate 50, the channel cross-sectional area is gradually reduced toward the groove channels 52 and 54 and further downstream thereof (the line width in FIG. 3 corresponds to the width of the groove channel). ). According to the structure concerning the current collector plate 50, the hydrogen flow rate can be made slower toward the upstream side where the flow rate of hydrogen is larger. Note that the flow path cross-sectional area may be changed stepwise or continuously. For example, each groove channel may be formed such that the channel cross-sectional area continuously decreases toward the downstream side.

  Further, as shown in FIG. 4, a plurality of hydrogen inlets 68 may be provided in one current collector plate 60, and a groove channel may be formed in each hydrogen inlet 68. Further, like the current collector plate 70 of FIG. 5, the groove flow path 72 extends from the hydrogen inlet 78 toward the center side in the plane, and the plurality of groove flow paths 74 extend radially from the central branch portion 73. It is good also as a structure.

Embodiment 2. FIG.
[Configuration of Embodiment 2]
Similar to the first embodiment, the fuel cell of the second embodiment includes a membrane electrode assembly, a gas diffusion layer, and a current collector plate as constituent elements. However, the fuel cell of Embodiment 2 is a type of fuel cell in which a porous body layer is inserted between the gas diffusion layer and the current collector plate. Further, the fuel cell of the second embodiment performs power generation while retaining the fuel gas (hydrogen) in the anode, as in the first embodiment. Further, as in the first embodiment, the cathode is an open system.

  In addition, the fuel cell of a type provided with a porous body layer therein has already been disclosed and publicly known in many documents. Therefore, the detailed description is abbreviate | omitted. In the following description, the structure of the current collector plate on the anode side, which is a feature of the second embodiment, will be described.

  FIG. 6 is a diagram for explaining the configuration of a current collector plate provided on the anode side of the fuel cell of the second embodiment. The anode-side current collector plate of this embodiment includes a plate 100 shown in FIG. 6A, an intermediate plate 120 shown in FIG. 6B, and a plate 140 shown in FIG. It is a thing.

  Note that the idea of forming the current collector plate as a single body by stacking three plates in this way has already been disclosed in, for example, JP-A-2006-164762 and JP-A-2006-216426. It is known. Therefore, in the following description, the characteristic configuration of the present embodiment will be described, and the description of other points similar to the known techniques such as the above-described documents (for example, a sealing method) will be omitted.

  FIG. 6A is a plan view of the plate 100 constituting the current collector plate according to the present embodiment. The plate 100 is in contact with the porous body layer on the anode side. A region surrounded by a broken line in the plane of the plate 100 in FIG. 6A indicates a region in contact with the porous body layer on the anode side. The plate 100 includes hydrogen supply through holes 102 and 104, an air supply through hole 106, an air discharge through hole 108, a coolant supply through hole 110, and a coolant discharge through hole 112. The hatched regions in FIG. 6A penetrate through the back side of the page as the above-mentioned through holes. The plate 100 includes slit-like through holes 103 and 105.

  FIG. 6B is a plan view of the intermediate plate 120 constituting the current collector plate according to the present embodiment. The plate 120 includes hydrogen supply through holes 122, 124, air supply through holes 126, air discharge through holes 128, coolant supply through holes 130 (130a, 130b), and coolant discharge through holes 132 (132a, 132b). The hatched regions in FIG. 6B penetrate through the back side of the paper as the respective through holes. The hydrogen supply through hole 122 includes a distribution part 122 a and a distribution part 122 b extending in the plane of the intermediate plate 120.

  The coolant supply through hole 130 and the coolant discharge through hole 132 are connected by a plurality of linear through holes extending in the center of the intermediate plate 120. The coolant supply through hole 130 is divided into two parts (coolant supply through holes 130 a and 130 b) by the distribution part 122 b of the hydrogen supply through hole 122. The coolant discharge through-hole 132 is also divided into two parts by the distribution part 124b.

  FIG.6 (c) is a top view of the plate 140 which comprises the current collecting plate concerning this embodiment. The plate 140 is in contact with the porous body layer on the cathode side. A region surrounded by a broken line in the plane of the plate 140 in FIG. 6C indicates a region in contact with the porous body layer on the cathode side. The plate 140 includes hydrogen supply through holes 142 and 144, an air supply through hole 146, an air discharge through hole 148, a coolant supply through hole 150, and a coolant discharge through hole 152. The hatched regions in FIG. 6C penetrate through the back side of the paper as the through holes. The plate 140 includes slit-shaped through holes 147 and 149.

  When the three plates illustrated in FIGS. 6A to 6C are stacked, the through holes at the corresponding positions communicate with each other. Specifically, the hydrogen supply through holes 102, 122, and 142 are connected, and the hydrogen supply through holes 104, 124, and 144 are connected. Further, the through hole 103 is connected to the distribution parts 122a and 122b of the hydrogen supply through hole 122, and the through hole 105 is connected to the distribution parts 124a and 124b of the hydrogen supply through hole 124, respectively.

  The air supply through holes 106, 126, and 146 are connected to the air discharge through holes 108, 128, and 48, respectively. The coolant supply through holes 110, 130, and 150 are connected to the coolant discharge through holes 112, 132, and 152, respectively. When forming a fuel cell stack by alternately stacking current collector plates, membrane electrode assemblies, etc., anode gas supply manifolds can be formed by connecting the hydrogen supply through holes of each current collector plate. Further, the coolant supply manifold and the coolant discharge manifold can be formed by connecting the coolant supply through hole and the coolant discharge through hole of each current collector plate, respectively.

  FIG. 7 is a cross-sectional view taken along line AA in a state where the three plates illustrated in FIGS. 6A to 6C are stacked. As a result of stacking the three plates, one current collector plate is formed. FIG. 7 assumes a state in which a plurality of fuel cells are stacked to form a fuel cell stack. In this case, the current collector plate also functions as a separator.

  In FIG. 7, the porous body layer on the anode side of one fuel cell and the porous body layer on the cathode side of another fuel cell located across the current collector plate are indicated by broken lines. In practice, a plurality of laminated bodies in which a membrane electrode assembly, a gas diffusion layer and a porous body layer are sequentially laminated and a current collector plate are alternately laminated. In FIG. 7, for convenience of explanation, the current collector plate according to the present embodiment and the state of the vicinity thereof are partially illustrated.

  As shown in FIG. 7, when three plates are stacked, the through hole 103 and the distribution parts 122a and 122b are connected, and the through hole 105 and the distribution parts 124a and 124b are connected. The distributors 122a, 122b, 124a, and 124b are covered from the anode side by the plate 140. As a result, the through holes 103 and 105 each form a groove flow path along the surface on the anode side of the current collector (in a direction penetrating the paper surface in FIG. 7). The two groove flow paths formed by the through holes 103 merge with the hydrogen supply through holes 122, and the two groove flow paths formed by the through holes 105 merge with the hydrogen supply through holes 124, respectively.

  As described above, the distributors 122a and 122b are connected to the hydrogen supply through hole 122, and the distributors 124a and 124b are connected to the hydrogen supply through hole 124, respectively. Therefore, by flowing hydrogen into the hydrogen supply through holes 122 and 124, hydrogen can be supplied to the porous body layer from the through holes 103 and 105 as shown by arrows in FIG. On the cathode side, air flows from the through hole 147 into the porous body layer as indicated by an arrow in FIG. Hydrogen and air flowing into the porous body layer are subjected to a power generation reaction in the membrane electrode assembly through the gas diffusion layer. On the cathode side, thereafter, air (cathode off-gas) flows out from the porous body layer through the through hole 149. This cathode off gas is normally discharged to a cathode exhaust system (not shown).

[Operation and Effect of Embodiment 2]
According to the second embodiment, the plurality of groove channels extend along the surface direction of the current collector plate, and two groove channels are connected to one hydrogen supply through hole. For this reason, in the same way as in the case where hydrogen flows from the hydrogen inlet 20 to the plurality of groove channels in the first embodiment, the nitrogen inside the groove channel is reduced by flowing hydrogen from the hydrogen supply through hole to each groove channel. Distributing to each groove channel, nitrogen concentration can be mitigated. Thus, according to the present embodiment, as in the first embodiment, it is possible to effectively prevent the concentration of nitrogen to one place in the anode surface by devising the structure of the current collector plate.

  Moreover, according to this embodiment, the following effects are also acquired. FIG. 8 is a diagram for explaining the operation and effect of the fuel cell of the second embodiment. FIG. 8 shows a plan view of the plate 100 also shown in FIG. As described above, when hydrogen is introduced from the hydrogen supply through holes 122 and 124, the hydrogen flows out of the through holes 103 and 105.

  As described in FIG. 7, when the plate 100 is in contact with the porous body layer, the hydrogen flowing out from the through holes 103 and 105 flows into the porous body layer. The hydrogen that has flowed into the porous body layer flows in the vertical direction along the surface direction of the plate 100 as indicated by arrows in FIG. As a result, hydrogen easily spreads in the porous body layer, and according to this, there is an advantage that it is possible to prevent generation of a region where power generation is impossible due to nitrogen concentration.

  FIG. 9 is a diagram showing a structure of a plate 200 that is a comparative example with respect to the second embodiment. Unlike the plate 100, the plate 200 has through holes 203 and 205 at an upper end and a lower end in a region where the porous body layer is in contact, respectively. The other points are the same as those of the plate 100. When comparing the hydrogen flow distance (distance in the direction of the arrow) between the case where hydrogen is introduced from the end side of the porous body layer as shown in FIG. 9 and the case of this embodiment of FIG. Thus, it can be seen that the flow distance of hydrogen can be shortened by flowing hydrogen from the plane of the porous body layer.

  Further, according to the configuration of the second embodiment, the coolant supply through hole and the coolant discharge through hole are divided by the hydrogen supply through hole in the plane of the plate 140. As a result, while maintaining the cooling performance by securing a space for the coolant to flow in the plane of the current collector plate, the branch portion of the through hole for supplying hydrogen is arranged at the center side in the plane of the current collector plate (that is, the porous body). To the middle side of the layer). In addition, the layout of the intermediate plate 120 as viewed in the plane direction makes it possible to guide the through holes for supplying hydrogen to the in-plane region of the porous body layer while effectively using the in-plane space. It can also be said.

  In the second embodiment described above, a membrane electrode assembly (not shown) overlaps the current collector plate in which the plate 100, the intermediate plate 120, and the plate 140 are stacked on the “power generator” in the first invention. The porous body layers positioned respectively correspond to the “gas supply member” in the first invention. In the second embodiment, the through hole 103 and the distribution parts 122a and 122b are connected to each other, and the through hole 105 and the distribution parts 124a and 124b are connected to each other. Is formed. Further, the through holes 102 and 104 for supplying hydrogen correspond to the “gas inlet” in the first invention.

  In addition, the idea of Embodiment 1 can be combined with Embodiment 2 as follows. For example, the shape in the surface direction of the through holes 103 and 105 of the plate 100 may be a shape (a pattern like the groove channel described in FIGS. 1, 3, 4, and 5) extending in a plurality of branches. You may arrange | position a through-hole so that the position of a downstream edge part may be disperse | distributed to the whole contact area | region (area | region enclosed in the rectangle with the broken line in FIG. 6) with a porous body layer. Further, the width of the through hole may be changed continuously or stepwise so that the channel cross-sectional area becomes smaller toward the downstream side.

  In the second embodiment, the mode in which three current plates are formed by stacking three plates has been described. However, the present invention is not limited to this. Of course, the current collector plate is constructed by appropriately stacking two, four, five, or other plural plates as appropriate, using a method such as three-dimensionally forming a through hole in one plate-like member. A gas supply member having a groove channel may be formed.

Embodiment 3 FIG.
[Configuration and Operation of Embodiment 3]
The third embodiment is a type of fuel cell in which a porous body layer is inserted between a gas diffusion layer and a current collector plate, as in the second embodiment. However, the fuel cell of the third embodiment is different from the second embodiment in that the groove channel is formed not in the current collector plate but in the porous body layer. The current collecting plate may have a known configuration as disclosed in, for example, Japanese Patent Application Laid-Open Nos. 2006-164762 and 2006-216426. However, in the current collector plate, a hydrogen inlet for joining the groove flow path formed in the porous body layer is formed as a groove or a through hole. This is because hydrogen can be supplied from the outside to the groove channel by using this hydrogen inlet.

  In the porous body layer, a groove channel is formed on the surface of the porous body layer on the side in contact with the membrane electrode assembly along the surface direction in the same manner as in the first embodiment. The groove channel further extends in the thickness direction of the porous body layer and joins the hydrogen inlet. In addition, the configuration of the membrane electrode assembly, the gas diffusion layer, the cathode side, and the like are the same as those in the second embodiment. By flowing hydrogen into the groove channel having a pressure loss smaller than that of the porous body layer, the effect of mitigating nitrogen concentration can be obtained as in the above embodiments.

  In the above-described third embodiment, the membrane electrode assembly (not shown) is the “power generation body” in the first invention, and the current collector plate and the porous body layer (not shown) are the “gas supply member” in the first invention. The groove channel formed in the porous body layer is the “groove channel” in the first invention, and the hydrogen inlet formed in the current collector plate is the “gas flow” in the first invention. Each corresponds to an “entrance”.

Embodiment 4 FIG.
In the third embodiment, the groove channel is formed on the surface of the porous body layer in contact with the membrane electrode assembly. On the other hand, in Embodiment 4, the groove flow path is provided on the surface of the porous body layer on the side in contact with the current collector plate. Other configurations can be the same as those in the third embodiment. By flowing hydrogen through the plurality of groove channels, nitrogen is dispersed in the plane of the fuel cell, and the effect of mitigating nitrogen concentration can be obtained as in the first to third embodiments.

  As a modification of the fourth embodiment, a plurality of tubular channels may be formed so as to extend through the inside of the porous body layer. Here, the “tubular flow path” is a flow path obtained by forming a tubular space penetrating in the surface direction inside the porous body layer. However, the fine pores inherent to the porous body layer itself are not included in the tubular flow path. That is, the tubular flow path has a sufficiently large diameter at least as compared with the pore diameter of the porous body layer.

  The downstream end of the tubular flow channel is terminated in the plane of the porous body layer in the same manner as the groove flow channel of the first to third embodiments. Then, the upstream side of each tubular channel is joined to the hydrogen inlet of the current collector plate. As a result, a tubular flow path that extends while branching in the plane direction of the porous body layer and has a number of dead ends in the plane is formed. Hydrogen flows through this tubular flow path having a pressure loss smaller than that of the porous body layer, and nitrogen is dispersed in the plane, so that the effect of mitigating nitrogen concentration can be obtained as in the above embodiments.

Embodiment 5 FIG.
The fifth embodiment of the present invention will be described below. The fifth embodiment is provided by configuring a fuel cell system using any of the fuel cells according to the first to fourth embodiments described above.

  The fuel cell system according to Embodiment 5 includes a mode in which almost all of the supplied fuel gas is consumed by the catalyst layer (anode reaction portion) of the anode (hereinafter, this mode is also referred to as “dead end operation”). A fuel cell system (hereinafter, such a system is also referred to as a “dead end system”). The term “almost all fuel gas” means all fuel gas consumed with power generation except for the fuel gas that has moved from the anode to the cathode side by so-called cross leak and decreased from the anode.

  In other words, the dead-end system is a fuel cell system that continuously generates power without exhausting the gas in the anode electrode. The dead-end system is continued in a state where the partial pressure of the impurity (specifically, for example, nitrogen) at the anode electrode is balanced with the partial pressure of the impurity (specifically, for example, nitrogen) at the cathode electrode. It is a fuel cell system that generates electricity automatically.

  Specifically, in the fifth embodiment, first, a fuel cell stack is configured by stacking a plurality of the fuel cells of any of the first to third embodiments. The fuel cell stack includes an anode gas supply manifold that extends through the fuel cell in the stacking direction. For example, as described in the second embodiment, the anode gas supply manifold is formed as a fuel cell stack by forming a through hole in the thickness direction of the current collector plate and connecting the through hole and the groove flow path. At this time, it can be formed by communicating each through hole of the current collector plate.

  The fuel cell stack configured as described above also includes various manifolds such as a cathode gas supply manifold, a cathode gas discharge manifold, and a coolant distribution manifold. These manifolds are also provided in the fuel cell stack as appropriate in the same manner as in the second embodiment or using a conventional known technique.

  For such a fuel cell stack, an anode side system and a cathode side system are respectively configured. The system on the anode side can be configured by connecting the above-described anode gas supply manifold to a hydrogen tank via a fuel supply control valve such as an injector or a valve. Moreover, the system on the cathode side can be configured as an open system including an air compressor or the like, as in the prior art.

  During power generation, a desired amount of hydrogen is supplied by controlling the fuel supply control valve described above from the end (introduction port) of the anode gas supply manifold located at the end of the fuel cell stack. In the process of consuming the supplied fuel gas, as described above, the nitrogen partial pressure of the anode electrode is balanced with the nitrogen partial pressure of the cathode electrode, and then power generation is continued.

  According to the fifth embodiment described above, the present invention is a fuel cell system including a mode in which almost all the supplied fuel gas is consumed at the anode from a different viewpoint from the first to fourth embodiments. An inlet (manifold communication portion) for introducing fuel gas (anode gas) into the fuel cell (power generation cell) and an anode gas supplied from the inlet are branched from each other to guide the fuel gas in the in-plane direction of the fuel cell. A plurality of groove flow paths, and the ends of the branched groove flow paths are arranged so as to be dispersed in the plane of the fuel cell. Provided.

It is a top view of the current collection board concerning the fuel cell of Embodiment 1 of the present invention. It is a schematic diagram for demonstrating the phenomenon that an impurity is concentrated. 6 is a diagram showing a modification of the first embodiment. FIG. 6 is a diagram showing a modification of the first embodiment. FIG. 6 is a diagram showing a modification of the first embodiment. FIG. It is each top view of the three plates which comprise the current collecting plate concerning the fuel cell of Embodiment 2 of this invention. FIG. 5 is a cross-sectional view of a current collector plate according to a second exemplary embodiment. 6 is a plan view of a current collector plate according to a fuel cell of Embodiment 2. FIG. 10 is a diagram illustrating a comparative example with respect to Embodiment 2. FIG.

Explanation of symbols

10 Current collecting plate 12, 14, 16, 18, 52, 72, 74 Groove flow path 20, 68, 78 Hydrogen inlet 50, 60, 70 Current collecting plate 73 Branch part 100, 140 Plate 102, 104, 142, 144 Through hole for hydrogen supply 103, 105, 147, 149 Through hole 106, 126, 146 Through hole for air supply 108, 128, 148 Through hole for air discharge 110, 130, 150 Through hole for cooling liquid supply 112, 132, 152 Through hole 120 for cooling liquid discharge Intermediate plate 122 Through holes 122a and 122b for supplying hydrogen Distributing part 124 Through holes 124a and 124b for supplying hydrogen Distributing part

Claims (2)

Catalyst layer is formed on both surfaces of the electrolyte membrane, supplied with fuel gas containing hydrogen to the anode catalyst layer on one surface side of the both sides of the catalyst layer, the cathode of the other surface side of the both sides of the catalyst layer A power generator for generating electricity by receiving supply of oxidizing gas containing oxygen to the catalyst layer;
It is arranged so as to overlap the anode catalyst layer and extends along a gas inlet into which the fuel gas flows and a surface facing the catalyst layer on the one surface side, the downstream side terminates in the surface, and the upstream side A gas supply member comprising a plurality of groove flow paths that merge with the gas inlet;
A fuel cell system having a fuel cell Ru provided with,
The gas supply member includes a current collector plate disposed to overlap the anode catalyst layer,
The groove channel is formed on a surface of the current collector plate facing the catalyst layer;
The plurality of groove flow paths merge in the plane of the gas supply member to form a branching branch in the plane;
The downstream end of each of the plurality of groove channels is disposed over the entire area of the gas supply member facing the anode catalyst layer and overlapping the anode catalyst layer,
The groove channel is formed such that the channel cross-sectional area in the flow direction of the fuel gas decreases toward the downstream side when viewed from the gas inlet,
The plurality of groove channels are
A plurality of main groove passages extending from a branch portion provided in the vicinity of the center of the current collector plate in the plane and arranged radially around the branch portion;
A plurality of branches are formed from each of the plurality of main groove flow paths, and the downstream end portions of the gas supply members face the anode catalyst layer over the entire region overlapping the anode catalyst layer. An arranged branch channel,
Including
The plurality of main groove channels are
A plurality of first main groove channels having the branch channel;
A second main groove channel provided between the plurality of first main groove channels and not having the branch channel;
Including
The gas supply member does not have an exhaust passage for exhausting the fuel off gas from the catalyst layer,
A fuel tank communicating with the gas inlet of the gas supply member;
A fuel cell system characterized by performing a dead-end operation in which power generation is continuously performed in a state where the partial pressure of the impurity on the anode catalyst layer side is balanced with the partial pressure of the impurity on the cathode catalyst layer side. The fuel cell system according to claim 1, wherein the first main groove flow paths and the second main groove flow paths are alternately arranged.

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