JP6406170B2 - Gas flow path forming plate for fuel cell and fuel cell stack - Google Patents

Description

  The present invention is formed by laminating a plurality of gas flow path forming plates that are interposed between a membrane electrode assembly and a flat flat separator to constitute a single cell separator of a fuel cell, and a plurality of the single cells. The present invention relates to a fuel cell stack.

  For example, a polymer electrolyte fuel cell includes a fuel cell stack formed by stacking a plurality of single cells each including a membrane electrode assembly and a pair of separators sandwiching the membrane electrode assembly.

  As such a separator, there is one having a flat flat separator and a gas flow path forming plate interposed between the membrane electrode assembly and the flat separator (for example, see Patent Document 1).

  A plurality of concave grooves extending in parallel to each other are formed on a surface of the gas flow path forming plate facing the membrane electrode assembly, and the concave grooves form a gas flow path for circulating fuel gas or oxidant gas. Is done. In addition, a plurality of concave grooves extending in parallel to each other are formed on the surface of the gas flow path forming plate facing the flat separator, and the concave grooves are used to discharge water generated during power generation. It is said. The ditch | groove which forms a water flow path is located between the two ditch | grooves which form a gas flow path. The gas flow path forming plate is formed with a communication path that connects the gas flow path and the water flow path. In such a fuel cell stack, water generated with power generation in the membrane electrode assembly flows into the gas flow path of the gas flow path forming plate, and flows into the water flow path through the communication path. And it is discharged | emitted outside the water flow path by the flow pressure of the fuel gas or oxidant gas which flows through a water flow path.

  By the way, when the flow rate of the fuel gas or the oxidant gas is increased in order to increase the power generation amount, a lot of water is generated in the membrane electrode assembly. In this case, there is a risk that the water discharge through the water flow channel will not be in time, the water in the water flow channel will flow into the gas flow channel again through the communication channel, and the gas flow channel will overflow. As a result, the pressure loss of the gas flowing through the gas flow path increases, or the diffusion of the gas to the membrane electrode assembly side is hindered, thereby reducing the power generation performance.

  On the other hand, in the gas flow path forming plate described in Patent Document 1, the flow path cross-sectional area of the outlet opening is increased by expanding the part including the outlet opening of the water flow path more than the part upstream of the same part. It is larger than the cross-sectional area of the upstream portion. Thereby, since the diameter of the water droplet at the outlet opening is increased, the surface tension of the water droplet, that is, the adhesion force acting between the water droplet and the edge of the outlet opening of the water channel is reduced. As a result, the pressure required to push out water droplets through the outlet opening of the water channel is reduced, and water can be discharged to the outside through the water channel even if the gas has a lower flow rate and lower flow pressure.

Japanese Patent Laid-Open No. 2015-15218

  By the way, in the case of the gas flow path forming plate described in Patent Document 1, the gas flow path is narrowed by expanding the portion including the outlet opening of the water flow path. As a result, the pressure loss of the gas flowing through the gas flow path is increased, and the system performance may be degraded.

  An object of the present invention is to provide a fuel cell gas flow path forming plate and a fuel cell stack capable of enhancing the drainage performance of a water flow path and suppressing an increase in gas pressure loss in the gas flow path. It is in.

  A gas flow path forming plate for a fuel cell for achieving the above object constitutes a single cell separator of a fuel cell interposed between a membrane electrode assembly and a flat flat separator, Formed on the surface facing the membrane electrode assembly, formed on the back surface of a plurality of concave groove-like gas flow paths extending in parallel with each other and between the two adjacent gas flow paths A plurality of groove-shaped water flow paths, and a plurality of communication paths communicating the gas flow path and the water flow path are formed on the protrusion, and an outlet end surface of the water flow path is the water flow path. It is inclined with respect to the stretching direction.

  A fuel cell stack for achieving the above object is formed by stacking a plurality of single cells, and the single cell sandwiches the membrane electrode assembly and the membrane electrode assembly. A pair of separators, and one of the separators includes the flat separator and the fuel cell gas flow path forming plate interposed between the membrane electrode assembly and the flat separator. .

  According to this configuration, since the outlet end surface of the water channel is inclined with respect to the extending direction of the water channel, the outlet end surface of the water channel is compared with the configuration in which the outlet end surface is orthogonal to the extending direction of the water channel. The area of the outlet opening is increased. Moreover, the diameter of the water droplet formed in the outlet opening becomes larger as the area of the outlet opening of the water channel becomes larger. From these things, according to the said structure, the diameter of the water droplet formed in the exit opening of a water flow path becomes large. For this reason, the surface tension of the water droplet, that is, the adhesion force acting between the water droplet and the edge of the outlet opening of the water channel is reduced. Accordingly, the pressure required to push out the water droplets through the outlet opening of the water flow path is reduced, and water can be discharged through the water flow path even if the gas has a lower flow rate or a lower flow pressure.

  Further, in the above configuration, in order to improve the drainage of water in the water flow path, the outlet end face of the water flow path is merely inclined with respect to the extending direction of the water flow path. Will not be affected.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to improve the drainage property of a water flow path, the increase in the pressure loss of the gas in a gas flow path can be suppressed.

Sectional drawing of a fuel cell stack about one Embodiment of the gas flow path formation board for fuel cells, and a fuel cell stack. The perspective view of the 1st separator in the embodiment. The elements on larger scale of FIG. (A) is the fragmentary sectional view along the aa line of FIG. 3, (b) is the fragmentary sectional view along the bb line of FIG. The expanded sectional view which expands and shows the exit part of the water flow path of the embodiment. (A), (b) is a schematic diagram of a gas flow path and a communicating path. (A)-(d) is sectional drawing centering on a communicating path, Comprising: Explanatory drawing explaining the effect | action of the same embodiment. The perspective view of the gas flow path formation board which comprises the 1st separator of a modification. The expanded sectional view which expands and shows the exit part of the water flow path of the modification. The perspective view of the gas flow path formation board which comprises the 1st separator of another modification. The enlarged plan view which expands and shows the exit part of the water flow path of the modification.

Hereinafter, an embodiment will be described with reference to FIGS.
As shown in FIG. 1, the polymer electrolyte fuel cell stack is formed by stacking a plurality of single cells 10. In the figure, the upper unit cell 10 has a cross-sectional shape cut at a position where water channels 26 and 36 described later are shown, while the lower unit cell 10 includes gas channels 25 and 35 described later. The cross-sectional shape cut | disconnected in the position shown is shown.

  Each unit cell 10 includes a first frame 11 and a second frame 12 each having a rectangular frame shape, and the outer edge portion of a known membrane electrode assembly 13 having a rectangular sheet shape is sandwiched between the frames 11 and 12. Has been.

  The membrane electrode assembly 13 includes a solid polymer electrolyte membrane 14, and the solid polymer electrolyte membrane 14 is sandwiched between well-known electrode catalyst layers 15 and 16, respectively. Further, well-known gas diffusion layers 17 and 18 are provided on the surfaces of the electrode catalyst layers 15 and 16, respectively.

The membrane electrode assembly 13 is sandwiched by the first separator 20 and the second separator 30 from the cathode side (lower side in the figure) and the anode side (upper side in the figure), respectively.
The first separator 20 includes a flat flat separator 21 and a gas flow path forming plate 22 interposed between the flat separator 21 and the membrane electrode assembly 13.

The second separator 30 includes a flat flat separator 31 and a gas flow path forming plate 32 interposed between the flat separator 31 and the membrane electrode assembly 13.
The flat separators 21 and 31 and the gas flow path forming plates 22 and 32 are made of, for example, a stainless steel plate.

  A supply passage 41 for supplying an oxidant gas from an oxidant gas supply source (not shown) to the gas flow path 25 by the first frame 11 and the flat separator 21, and a gas flow path for the oxidant gas that has not been used for power generation 25 and a discharge passage 42 for discharging to the outside.

  In addition, the second frame 12 and the flat separator 31 supply a supply passage 51 for supplying a fuel gas from a fuel gas supply source (not shown) to the gas passage 35, and a fuel passage that has not been used for power generation in the gas passage 35. And a discharge passage 52 for discharging to the outside.

  In addition, in the part shown in FIG. 1, the gas flow path forming plate 32 of the second separator 30 has a shape in which the gas flow path forming plate 22 of the first separator 20 is turned upside down and turned left and right. Therefore, hereinafter, the gas flow path forming plate 22 of the first separator 20 will be described, and the gas flow path forming plate 32 of the second separator 30 will be denoted by the reference numerals of the respective parts of the gas flow path forming plate 22 of the first separator 20. A duplicate description is omitted by adding a symbol “3 *” obtained by adding “10” to “2 *”. In some cases, a symbol “37 *” obtained by adding “100” to the symbol “27 *” is added.

Next, the structure of the gas flow path forming plate 22 will be described.
As shown in FIG. 2, the gas flow path forming plate 22 has a substantially corrugated cross section, and is formed, for example, by roll forming a single metal plate material such as a stainless steel plate. A plurality of inner ridges 23 extending in parallel to each other are formed on the upper surface of the gas flow path forming plate 22, and the top surface of the inner ridge 23 is in contact with the membrane electrode assembly 13. In addition, a plurality of gas flow paths 25 are formed between the two adjacent inner ridges 23 to form a concave groove and allow the oxidant gas to flow therethrough.

  A plurality of outer ridges 24 extending in parallel to each other are formed on the lower surface of the gas flow path forming plate 22, and the top surface of the outer ridge 24 is in contact with the flat separator 21. In addition, a plurality of water flow paths 26 are formed on the back surface of the inner ridge 23, each of which has a concave groove shape and discharges water generated with power generation in the membrane electrode assembly 13. Accordingly, the outer ridge 24 is located between two adjacent water flow paths 26 and defines the two water flow paths 26.

  As shown in FIGS. 2 to 4, in the gas flow path forming plate 22, the extending direction of the protrusions 23, 24, that is, the extending direction of the gas flow path 25 (hereinafter simply referred to as the extending direction L). A plurality of ribs 271 extending along a direction orthogonal to the direction (hereinafter referred to as the width direction W) are formed.

  As shown in FIG. 2, each gas flow path 25 is formed with a plurality of pairs each formed of a pair of ribs 271 formed close to each other in the extending direction L. The sets of the pair of ribs 271 are provided at equal intervals in the extending direction L. The plurality of ribs 271 are formed by partially bending the protrusions 23 and 24 when the gas flow path forming plate 22 is formed by roll forming a metal plate along the width direction W. It is formed.

  As shown in FIGS. 2 to 4, the plurality of ribs 271 are formed on the inner ridge 23 of the gas flow path forming plate 22, thereby connecting a plurality of communication channels that connect the gas flow path 25 and the water flow path 26. A passage 27 is formed. As shown in FIGS. 4A and 4B, the ribs 271 protrude into the gas channel 25 and the water channel 26, respectively. As shown in FIGS. 2 to 4, the outer ridge 24 is formed with a communication groove 272 that connects the water flow paths 26 adjacent to each other.

  The rib 271 is closer to the top surface of the outer ridge 24 than the top surface of the inner ridge 23 in the thickness direction of the gas flow path forming plate 22 (vertical direction in FIGS. 4A and 4B). Is provided. For this reason, the cross-sectional area of the portion of the rib 271 that blocks the water flow path 26 is larger than the cross-sectional area of the portion that blocks the gas flow path 25. Therefore, even if the channel cross-sectional area of the gas channel 25 and the channel cross-sectional area of the water channel 26 at the position where the rib 271 does not exist in the extending direction L are set to be the same, the pressure loss in the entire water channel 26 is The pressure loss in the entire gas flow path 25 becomes larger. The shape and size of the communication path 27 are set so that the pressure loss in the communication path 27 is larger than the pressure loss in the gas flow path 25. For these reasons, the oxidant gas mainly flows through the gas flow path 25 with a small pressure loss.

  As shown in FIGS. 1, 2, and 5, the outlet end face 28 of the water channel 26 is inclined with respect to the extending direction L of the water channel 26. That is, the outlet end face 28 is inclined so as to be positioned on the outer side in the extending direction L as it approaches the top face of the outer protrusion 24 in the thickness direction of the gas flow path forming plate 22 (vertical direction in FIG. 5).

  The flow path cross-sectional areas of the plurality of gas flow paths 25 are the same throughout the extending direction L of the gas flow path 25 except for the portion of the communication path 27 and the outlet opening. Further, the channel cross-sectional areas of the plurality of water channels 26 are the same throughout the extending direction L of the water channel 26 except for the portion of the communication channel 27 and the outlet opening 29.

Next, the operation of this embodiment will be described.
As shown in the lower unit cell 10 in FIG. 1, when the fuel gas is supplied into the gas flow path 35 through the supply passage 51, the fuel gas flows into the gas diffusion layer 18 through the gas flow path 35. The fuel gas passes through the gas diffusion layer 18 and is diffused and supplied to the electrode catalyst layer 16.

  When the oxidant gas is supplied into the gas flow path 25 through the supply passage 41, the oxidant gas flows into the gas diffusion layer 17 through the gas flow path 25. The oxidizing gas passes through the gas diffusion layer 17 and is diffused and supplied to the electrode catalyst layer 15.

  When the fuel gas and the oxidant gas are supplied to the membrane electrode assembly 13 in this manner, power generation is performed by an electrochemical reaction in the membrane electrode assembly 13. At this time, the water generated with the power generation mainly flows into the gas flow path 25 of the gas flow path forming plate 22 on the cathode side.

  6A and 6B, a part of this water flows in the gas flow path 25 by the flow pressure of the oxidant gas flowing in the gas flow path 25, as indicated by the thick thick arrows. . And water is discharged | emitted outside through the discharge channel | path 42 (refer FIG. 1). As described above, the pressure loss in the communication passage 27 is larger than the pressure loss in the gas flow path 25. For this reason, as shown in FIG. 6B, the oxidant gas mainly flows through the gas flow path 25. Thereby, most of the water S present in the gas flow path 25 moves in the gas flow path 25 toward the discharge passage 42 while being pushed by the oxidant gas. In addition, as shown by thin arrows in FIG. 6B, some water is introduced into the water flow path 26 through the communication path 27.

  At this time, the water introduced into the water channel 26 becomes water droplets due to the surface tension acting according to the opening area of the outlet opening 29 of the water channel 26. When the water flow path 26 is in a wet state, when the water droplets S are moored to the ribs 271, the water in the water flow path 26 becomes the priming water, and the water in the communication path 27 is guided into the water flow path 26 by capillary action and is described above. It is discharged through the outlet opening 29.

  Further, when there is no dry water in the water flow path 26, as shown in FIG. 7 (a), water is connected to each other on the top surface of the inner ridge 23 that is in contact with the gas diffusion layer 17. The water droplets S1 and S2 are formed by being guided into the passage 27 by capillary action.

  Then, when the water droplets S1 and S2 grow as water is further guided, both the water droplets S1 and S2 are combined to form one water droplet S3 as shown in FIG. 7B. Immediately after this combination or when the water droplet S3 further grows, the water droplet S3 comes into contact with the rib 271. Then, as shown in FIG. 7C, when the water droplet S3 reaches the gap between the pair of ribs 271, the water droplet S3 is drawn into the gap by capillary action as shown in FIG. 7D. It is introduced into the water channel 26.

  As shown in FIG. 5, the outlet end face 28 of the water flow path 26 is inclined with respect to the extending direction L of the water flow path 26, so that the outlet end face is orthogonal to the extending direction L of the water flow path. Thus, the area of the outlet opening 29 of the water flow path 26 is increased. Further, the diameter of the water droplet S formed at the outlet opening 29 increases as the area of the outlet opening 29 of the water flow path 26 increases.

  For these reasons, the diameter of the water droplet S formed at the outlet opening 29 of the water flow path 26 increases as shown by the two-dot chain line in FIG. For this reason, the surface tension of the water droplet S, that is, the adhesion force acting between the water droplet S and the edge of the outlet opening 29 of the water channel 26 is reduced. Accordingly, the pressure required to push out the water droplets S through the outlet opening 29 of the water flow path 26 is reduced, and even if an oxidant gas having a lower flow rate or an oxidant gas having a lower flow pressure is used, water is supplied through the water flow path 26. Can be discharged.

  Further, in order to improve the drainage of water in the water flow path 26, the outlet end face 28 of the water flow path 26 is merely inclined with respect to the extending direction L of the water flow path 26, whereby the oxidant of the gas flow path 25 is obtained. The gas flow is not affected.

  A part of the water generated by power generation flows into the gas flow path 35 of the gas flow path forming plate 32 through the electrode catalyst layer 16 and the gas diffusion layer 18 on the anode side (upper side in FIG. 1). In the present embodiment, the anode-side gas flow path forming plate 32 has basically the same configuration as the cathode-side gas flow path forming plate 22, and therefore, in the anode-side gas flow path 35 and the water flow path 36 as well. The same action as the cathode side gas passage 25 and the water passage 26 is exhibited.

According to the fuel cell gas flow path forming plate and the fuel cell stack according to the present embodiment described above, the following effects can be obtained.
(1) The outlet end faces 28 and 38 of the water channels 26 and 36 are inclined with respect to the extending direction L of the water channels 26 and 36. For this reason, the above-described action is exhibited, and the drainage performance in the water flow paths 26 and 36 can be enhanced, and an increase in gas pressure loss in the gas flow paths 25 and 35 can be suppressed.

  (2) The flow passage cross-sectional areas of the plurality of gas passages 25 and 35 are the same throughout the extending direction L of the gas passages 25 and 35 except for the portions of the communication passages 27 and 37 and the outlet opening, and the plurality of water passages 26 , 36 are made the same in the entire extending direction L of the water flow paths 26, 36 except for the portions of the communication paths 27, 37 and the outlet opening 29. Therefore, it is possible to smoothly supply and discharge the gas through the gas flow paths 25 and 35 and smoothly discharge the water through the water flow paths 26 and 36.

<Modification>
In addition, the said embodiment can also be changed as follows, for example.
The gas flow path forming plates 22 and 32 may be formed of a metal plate material other than a stainless steel plate such as a titanium plate.

  As shown in FIGS. 8 and 9, the outlet end surface 128 of the water channel 126 extends in the extending direction L as it approaches the top surface of the inner protrusion 123 in the thickness direction of the gas channel forming plate 122 (vertical direction in the figure). The outlet end face 128 of the water flow path 126 may be inclined with respect to the extending direction L so as to be positioned outside of the water flow path 126. In addition, about the structure corresponding to the gas flow path formation board 22 of the said embodiment among the structures of the gas flow path formation board 122, the code | symbol which added "100" to the code | symbol "2 *" of the gas flow path formation board 22 respectively. A duplicate description is omitted by attaching “12 *”. Further, the communication groove 272 is denoted by the same reference numeral.

  Even in this case, since the outlet end surface 128 of the water channel 126 is inclined with respect to the extending direction L, the water channel is compared with the conventional configuration in which the outlet end surface is orthogonal to the extending direction L of the water channel. The area of the 126 outlet openings 129 is increased. Therefore, the same operation as in the above embodiment is achieved, and the effect according to the effects (1) and (2) of the above embodiment can be achieved.

  As shown in FIGS. 10 and 11, the water flow is such that the outlet end surface 228 of the water flow channel 226 is positioned on the outer side in the extending direction L as it approaches one end of the water flow channel 226 in the width direction W of the gas flow channel forming plate 222. The outlet end surface 228 of the path 226 may be inclined with respect to the extending direction L. In addition, about the structure corresponding to the gas flow path formation board 22 of the said embodiment among the structures of the gas flow path formation board 222, the code | symbol which added "200" to the code | symbol "2 *" of the gas flow path formation board 22 respectively. A duplicate description is omitted by attaching “22 *”. Further, the communication groove 272 is denoted by the same reference numeral.

  Even in this case, since the outlet end surface 228 of the water channel 226 is inclined with respect to the extending direction L, the outlet channel is compared with the conventional configuration in which the outlet end surface is orthogonal to the extending direction L of the water channel. The area of the outlet opening of 226 is increased. Therefore, the same operation as in the above embodiment is achieved, and the effect according to the effects (1) and (2) of the above embodiment can be achieved.

  In the above embodiment, the outlet end faces 28 and 38 of the water flow paths 26 and 36 are flat. However, the outlet end face only needs to be inclined with respect to the extending direction L of the water flow path. Can be stepped.

  In the above embodiment, the gas flow path forming plates 22 and 32 are provided on both the cathode side and the anode side of the membrane electrode assembly 13, but instead, only on the cathode side of the membrane electrode assembly 13. A gas flow path forming plate 22 may be provided, and a separator having no communication hole may be disposed on the anode side.

  DESCRIPTION OF SYMBOLS 10 ... Single cell, 11 ... 1st frame, 12 ... 2nd frame, 13 ... Membrane electrode assembly, 14 ... Solid polymer electrolyte membrane, 15, 16 ... Electrode catalyst layer, 17, 18 ... Gas diffusion layer, 20 ... 1st separator, 21 ... flat separator, 22 ... gas flow path forming plate, 23 ... inner ridge, 24 ... outer ridge, 25 ... gas flow path, 26 ... water flow path, 27 ... communication path, 271 ... rib, 272 ... Communication groove 28 ... Exit end face 29 ... Exit opening 30 ... Second separator 31 ... Flat separator 32 ... Gas flow path forming plate 33 ... Inner ridge 34 ... Outer ridge 35 ... Gas flow path , 36 ... water flow path, 37 ... communication path, 371 ... rib, 372 ... communication groove, 38 ... outlet end face, 39 ... outlet opening, 41 ... supply path, 42 ... discharge path, 51 ... supply path, 52 ... supply path.

Claims (3)

A gas flow path forming plate interposed between a membrane electrode assembly and a flat flat separator to constitute a single cell separator of a fuel cell,
A plurality of groove-shaped gas flow paths formed on a surface facing the membrane electrode assembly and extending in parallel with each other;
A plurality of groove-shaped water flow paths formed on the back surface of the ridge located between two adjacent gas flow paths,
A plurality of communication passages that connect the gas flow path and the water flow path are formed in the ridge,
The outlet end face of the water channel is inclined with respect to the extending direction of the water channel,
A fuel cell gas flow path forming plate. The flow path cross-sectional areas of the plurality of gas flow paths are the same throughout the extending direction of the gas flow path except for the portion of the communication path and the outlet opening of the gas flow path,
The flow passage cross-sectional areas of the plurality of water flow paths are the same throughout the extending direction of the water flow path except for the portion of the communication path and the outlet opening of the water flow path.
The gas flow path forming plate for a fuel cell according to claim 1. A fuel cell stack formed by stacking a plurality of single cells,
The single cell includes a membrane electrode assembly and a pair of separators sandwiching the membrane electrode assembly,
One said separator is equipped with the said flat separator and the gas flow path formation board for fuel cells of Claim 1 or Claim 2 interposed between the said membrane electrode assembly and the said flat separator. ing,
Fuel cell stack.