fuel cell

Abstract

This technology provides a way to reduce pressure loss that occurs when gas flows into a throttling section. [Solution] The fuel cell cell comprises a pair of separators, one having a cathode-side separator and the other an anode-side separator, which sandwich the power generator. The cathode-side separator has a plurality of grooves that form a cathode gas flow path through which cathode gas flows between it and the power generator, and a rib portion that isolates the plurality of grooves from each other and contacts the power generator. At least one of the plurality of grooves has a throttling portion that narrows the flow path cross-sectional area of ​​the cathode gas flow path, and a throttling upstream portion located in the groove on the inflow side where cathode gas flows into the cathode gas flow path, rather than the throttling portion. The rib portion is provided on both sides of the throttling upstream portion and has fine grooves that connect the throttling upstream portion and the grooves adjacent to the grooves having the throttling upstream portion, and the fine grooves are provided at an angle greater than 0 degrees and less than 90 degrees with respect to the direction of cathode gas flow of the throttling upstream portion.

Description

Technical Field

[0001] The present disclosure relates to fuel cells.

Background Art

[0002] A fuel cell in which a throttle portion is provided in a cathode gas flow path is known (see Patent Document 1). The flow path cross-sectional area of the throttle portion is smaller than that of other portions of the cathode gas flow path.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] There has been a problem of reducing the pressure loss that occurs when gas flows from a portion other than the throttle portion into the throttle portion.

Means for Solving the Problems

[0005] The present disclosure has been made to solve the above problems and can be realized in the following forms.

[0006] According to an embodiment of the present disclosure, a fuel cell is provided. The fuel cell includes a pair of separators having a cathode-side separator and an anode-side separator that sandwich a power generator. The cathode-side separator has a plurality of grooves that form a cathode gas flow path through which cathode gas flows between it and the power generator, and rib portions that isolate the plurality of grooves from each other and abut against the power generator. At least one of the plurality of grooves has a throttling portion that narrows the flow path cross-sectional area of ​​the cathode gas flow path, and a throttling upstream portion located in the groove on the inflow side of the cathode gas flow path, rather than the throttling portion. The rib portion is provided on both sides of the throttling upstream portion and has fine grooves that connect the throttling upstream portion and grooves among the plurality of grooves adjacent to the groove having the throttling upstream portion, and the fine grooves are inclined at an angle greater than 0 degrees and less than 90 degrees with respect to the flow direction of the cathode gas in the throttling upstream portion. In this type of fuel cell, when cathode gas flows from the upstream part of the throttling into the throttling section, the cathode gas flows into the fine grooves which are inclined at an angle greater than 0 degrees and less than 90 degrees with respect to the direction of cathode gas flow, thereby suppressing pressure loss.

[0007] Furthermore, this disclosure can be implemented in various forms, for example, as a separator for fuel cell cells, a fuel cell stack comprising multiple stacked fuel cell cells, or a method for manufacturing fuel cell cells. [Brief explanation of the drawing]

[0008] [Figure 1] This is an explanatory diagram showing a disassembled fuel cell. [Figure 2] This is a perspective view of section A in Figure 1. [Figure 3] This graph shows an example of the relationship between the angle of the micro-groove and the pressure loss. [Modes for carrying out the invention]

[0009] A. First Embodiment: Figure 1 is an exploded view of a fuel cell cell 100 in one embodiment of the present disclosure. Figure 2 is a perspective view of part A in Figure 1. The fuel cell cell 100 is a solid polymer fuel cell that generates electricity by receiving hydrogen as the cathode gas and oxygen as the anode gas as reaction gases. The fuel cell cell 100 comprises a power generation unit 10, a resin frame 20, a pair of separators 30 and 40, and a manifold hole 50.

[0010] The power generator 10 comprises an electrolyte membrane (not shown), catalyst layers (not shown) formed adjacent to both sides of the electrolyte membrane, and a gas diffusion layer (not shown) formed adjacent to one side of the catalyst layer. The electrolyte membrane is a solid polymer thin film that exhibits good proton conductivity in a wet state. The electrolyte membrane is composed of, for example, an ion exchange membrane made of a fluororesin. The catalyst layer comprises a catalyst that promotes the chemical reaction between hydrogen and oxygen, and carbon particles supporting the catalyst. The electrolyte membrane and catalyst layer together are also called a membrane electrode assembly (MEA).

[0011] The gas diffusion layer is provided adjacent to one of the catalyst layers. The gas diffusion layer diffuses the reaction gas used in the electrode reaction along the plane of the electrolyte membrane and is composed of a porous diffusion layer substrate. As the diffusion layer substrate, porous substrates with conductivity and gas diffusion properties such as carbon fiber substrates, graphite fiber substrates, and foamed metals are used. This electrolyte membrane, catalyst layer, and gas diffusion layer together are also called a membrane electrode gas diffusion layer assembly (MEGA).

[0012] The resin frame 20 is a frame-shaped resin sheet member having a hole 21 in the center. In this embodiment, polyethylene terephthalate (PET) is used for the resin frame 20. However, various other thermoplastic resin members such as polypropylene and polyethylene may be used as the resin member. The power generation element 10 is placed in the hole 21 of the resin frame 20. The bonded structure of the power generation element 10 and the gas diffusion layer provided on the other side of the power generation element 10 (the side with the catalyst layer) to the resin frame 20 is also called a bonded structure.

[0013] The pair of separators 30 and 40 are members that sandwich the power generator 10. More specifically, the cathode-side separator 30 is positioned adjacent to the cathode-side surface of the power generator 10. The anode-side separator 40 is positioned adjacent to the anode-side surface of the power generator 10. The separators 30 and 40 are formed, for example, by press molding a metal plate made of stainless steel, titanium, or an alloy thereof.

[0014] The cathode-side separator 30 has a plurality of grooves 31 and ribs 32. The grooves 31 are portions that sandwich the anode-side separator 40 and the power generator 10, forming a cathode gas flow path through which cathode gas flows between the cathode-side separator 30 and the cathode-side surface of the power generator 10. The cathode gas flows in the direction of arrow AR1. The ribs 32 are portions that separate the plurality of grooves 31 from each other and are in contact with the cathode-side surface of the power generator 10.

[0015] The groove 31 has a diaphragm 31a and a diaphragm upstream section 31b. In this embodiment, each of the multiple grooves 31 has multiple diaphragm 31a and multiple diaphragm upstream sections 31b. The diaphragm 31a is a section that narrows the cross-sectional area of ​​the cathode gas flow path and limits the flow rate of the cathode gas passing through it. The diaphragm upstream section 31b is a section of the groove 31 that is located on the inlet side of the cathode gas flow path, i.e., upstream of the diaphragm 31a. In this embodiment, the width of the diaphragm 31a is smaller than the width of the diaphragm upstream section 31b. Also, the depth of the diaphragm 31a is smaller than the depth of the diaphragm upstream section 31b.

[0016] The rib portion 32 has a plurality of micro-grooves 36. The plurality of micro-grooves 36 are provided in parallel on both sides of the aperture upstream portion 31b. The micro-grooves 36 communicate the aperture upstream portion 31b with the groove portion 31 that is adjacent to the groove portion 31 that has the aperture upstream portion 31b. The micro-grooves 36 are provided at an angle greater than 0 degrees and less than 90 degrees with respect to the flow direction of the cathode gas in the aperture upstream portion 31b. In this embodiment, the angle θ of the micro-grooves 36 with respect to the flow direction is 45 degrees.

[0017] The section A shown in Figure 1 is an enlarged view of the first groove 33, the second groove 34, and the third groove 35 among the multiple grooves 31. The first groove 33 and the second groove 34 are adjacent to each other. Also, the first groove 33 and the third groove 35 are adjacent to each other. That is, the first groove 33 is located between the second groove 34 and the third groove 35. Below, we will describe the fine grooves 36 provided on both sides of the upstream portion 31b of the apex of the first groove 33.

[0018] In this embodiment, the micro-groove 36 provided in the rib portion 32 located between the first groove portion 33 and the second groove portion 34 is referred to as the first micro-groove portion 36a. The micro-groove 36 provided in the rib portion 32 located between the first groove portion 33 and the third groove portion 35 is referred to as the second micro-groove portion 36b. The first micro-groove portion 36a connects the upstream portion 31b of the throttling of the first groove portion 33 and the second groove portion 34. Cathode gas flows from the first groove portion 33 to the second groove portion 34 through the first micro-groove portion 36a. The second micro-groove portion 36b connects the upstream portion 31b of the throttling of the first groove portion 33 and the third groove portion 35. Cathode gas flows from the first groove portion 33 to the third groove portion 35 through the second micro-groove portion 36b.

[0019] The resin frame 20 and the separators 30 and 40 have manifold holes 50. The manifold holes 50 connect the resin frame 20 and the separators 30 and 40, through which reaction gas or cooling water flows.

[0020] FIG. 3 is a graph showing an example of the relationship between the angle θ of the fine groove portion 36 and the pressure loss. The graph shown in FIG. 4 has the horizontal axis indicating the angle of the fine groove portion 36 with respect to the flow direction of the cathode gas. The vertical axis indicates the pressure loss when the cathode gas flows from the upstream portion 31b of the throttle to the throttle portion 31a. When the angle θ of the fine groove portion 36 is greater than 90 degrees, the probability that the cathode gas flows from the second groove portion 34 or the third groove portion 35 to the first groove portion 33 through the fine groove portion 36 is high, so the pressure loss increases. As shown in FIG. 4, the pressure loss decreases by making the angle θ of the fine groove portion 36 less than 90 degrees. Note that the angle θ of the fine groove portion 36 is preferably 30 degrees or more and 60 degrees or less.

[0021] In the present embodiment, when the cathode gas flows from the upstream portion 31b of the throttle to the throttle portion 31a, the cathode gas flows into the fine groove portion 36 provided at an angle greater than 0 degrees and less than 90 degrees with respect to the flow direction of the cathode gas, so that the pressure loss can be suppressed.

[0022] B. Other Embodiments: (B1) In the above-described embodiment, each of the plurality of groove portions 31 has a plurality of throttle portions 31a and a plurality of upstream throttle portions 31b. However, it is not limited to this, and the groove portion 31 may have only one throttle portion 31a and one upstream throttle portion 31b, respectively. Also, only at least one arbitrary groove portion 31 of the plurality of groove portions 31 may have a throttle portion 31a and an upstream throttle portion 31b.

[0023] (B2) In the above-described embodiment, the rib portions 32 have fine groove portions 36 provided on both sides of all the upstream throttle portions 31b. However, it is not limited to this, and the rib portions 32 may have fine groove portions 36 provided only on both sides of an arbitrary groove portion 31 of the plurality of upstream throttle portions 31b.

[0024] (B3) In the above-described embodiment, the anode-side separator 40 may also have a diaphragm, an upstream diaphragm, and a fine groove. More specifically, the plurality of grooves in the anode-side separator 40 that form an anode gas flow path between the anode-side separator 40 and the anode-side surface of the power generator 10 by sandwiching the power generator 10 between the cathode-side separator 30 and the anode-side separator 40 may have a diaphragm and an upstream diaphragm. In addition, the rib portion of the anode-side separator 40 that isolates the plurality of grooves of the anode-side separator 40 from each other may have a fine groove.

[0025] (B4) In the embodiment described above, the rib portion 32 has multiple fine grooves 36 arranged in parallel. However, the rib portion 32 may have only one fine groove 36 on each side of the upstream portion 31b of the throttling.

[0026] (B5) In the embodiment described above, the angles θ of the multiple micro-grooves 36 are all the same. However, the angle θ of each of the multiple micro-grooves 36 may be any angle as long as it is greater than 0 degrees and less than 90 degrees.

[0027] This disclosure is not limited to the embodiments described above, and can be implemented in various configurations without departing from its spirit. For example, the technical features in the embodiments corresponding to the technical features in each form described in the summary of the invention can be replaced or combined as appropriate in order to solve the problems described above or to achieve some or all of the effects described above. Furthermore, if a technical feature is not described as essential in this specification, it can be deleted as appropriate. [Explanation of symbols]

[0028] 10...Power generator, 20...Resin frame, 21...Hole, 30...Cathode-side separator, 31...Groove, 31a...Constriction, 31b...Upstream of constriction, 32...Rib, 33...First groove, 34...Second groove, 35...Third groove, 36...Fine groove, 36a...First fine groove, 36b...Second fine groove, 40...Anode-side separator, 50...Manifold hole, 100...Fuel cell cell

Claims

[Claim 1] It is a fuel cell cell, It comprises a pair of separators, one having a cathode-side separator and the other an anode-side separator that sandwich the power generation element. The cathode-side separator has a plurality of grooves that form a cathode gas flow path through which cathode gas flows between it and the power generator, and a rib portion that separates the plurality of grooves from each other and contacts the power generator. At least one of the plurality of grooves has a throttling portion that narrows the cross-sectional area of ​​the cathode gas flow path, and a throttling upstream portion located in the groove on the inflow side of the cathode gas flow path, rather than the throttling portion. The rib portion is provided on both sides of the upstream portion of the throttling, and is a fine groove portion that connects the upstream portion of the throttling with a groove portion among the plurality of groove portions that has the upstream portion of the throttling with a groove portion adjacent to the groove portion having the upstream portion of the throttling, and the fine groove portion is provided at an angle greater than 0 degrees and less than 90 degrees with respect to the flow direction of the cathode gas in the upstream portion of the throttling, in a fuel cell cell.

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