JP2009170314A - Fuel cell stack and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell stack for suppressing the backflow of impure gas into a fuel gas flow path, and to provide its manufacturing method. <P>SOLUTION: The fuel cell stack 100 comprises a plurality of laminated single cells 130 having the fuel gas flow paths, wherein a resistance part 25 is provided in each fuel gas flow path for suppressing the flow of fuel gas. It satisfies ΔOc/ΔPo≥r/(2(St2-1)), where ΔP<SB>c</SB>is pressure drop from the inlet to the outlet of the fuel gas flow path, ΔP<SB>o</SB>is pressure loss from the inlet of the fuel gas flow path to the resistance part, (1+r) is a maximum dispersion of flow path resistance from the inlet of the fuel gas flow path to the resistance part between the single cells, and St<SB>2</SB>is the stoichiometric ratio of fuel gas in the fuel gas flow path having minimum flow path resistance. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel cell stack and a method for manufacturing the same.

  A fuel cell is a device that generally obtains electric energy using hydrogen and oxygen as fuel. Since this fuel cell is excellent in terms of environment and can realize high energy efficiency, it has been widely developed as a future energy supply system.

  In this fuel cell, power is generated by supplying fuel gas to the anode and air to the cathode. Hydrogen in the fuel gas is consumed at the anode. In this fuel cell, in order to suppress the discharge amount of hydrogen from the anode, 0.02 to 4% by volume of gas with respect to the fuel gas supplied to the single cell at the discharge port of the fuel gas flow path of the single cell. Has been disclosed (see Patent Document 1).

JP 2007-66784 A

  However, in the fuel cell stack using the technique of Patent Document 1, impure gas discharged from a single cell may flow back to another single cell due to pressure loss variation between the single cells.

  An object of the present invention is to provide a fuel cell stack capable of suppressing the backflow of impure gas into the fuel gas flow path and a method for manufacturing the same.

A fuel cell stack according to the present invention is a fuel cell stack in which a plurality of single cells each having a fuel gas channel formed therein are stacked, and each fuel gas channel has a resistance for suppressing the flow of fuel gas. The pressure loss from the inlet to the outlet of the fuel gas flow path is ΔP _c , the pressure loss from the inlet of the fuel gas flow path to the resistance portion is ΔP _0, and the fuel gas flow path between the single cells is When the maximum flow resistance variation from the inlet to the resistance portion is (1 + r) and the stoichiometric ratio of the fuel gas in the fuel gas flow path having the minimum flow resistance is St ₂ , ΔP _c / ΔP ₀ ≧ r / (2 (St ₂ -1)) is satisfied.

In the fuel cell stack according to the present invention, the back flow of the fuel off gas between the single cells can be suppressed. In this case, the backflow of impure gas such as N ₂ gas that has permeated from the cathode to the fuel gas flow path is suppressed. As a result, output reduction of the fuel cell stack according to the present invention, catalyst deterioration, and the like can be suppressed.

Another fuel cell stack according to the present invention is a fuel cell stack in which a plurality of single cells each having a fuel gas channel formed therein are stacked, and each fuel gas channel is provided for suppressing the flow of fuel gas. A resistance part is provided, a pressure loss from the inlet to the outlet of the fuel gas flow path is ΔP _c , a pressure loss from the inlet of the fuel gas flow path to the resistance part is ΔP _0, and the fuel gas flow path between each single cell ΔP _c / ΔP, where (1 + r) is the maximum variation in flow path resistance and St ₂ is the stoichiometric ratio of the fuel gas in the fuel gas flow path in other single cells except the single cell having the maximum flow path resistance. ₀ ≧ r / (2 (St ₂ −1)) is satisfied.

In another fuel cell stack according to the present invention, the back flow of the fuel off gas between the single cells can be suppressed. In this case, the backflow of impure gas such as N ₂ gas that has permeated from the cathode to the fuel gas flow path is suppressed. As a result, output reduction of the fuel cell stack according to the present invention, catalyst deterioration, and the like can be suppressed.

Another fuel cell stack according to the present invention is a fuel cell stack in which a plurality of single cells each having a fuel gas channel formed therein are stacked, and each fuel gas channel is provided for suppressing the flow of fuel gas. A resistance part is provided, a pressure loss from the inlet to the outlet of the fuel gas flow path is ΔP _c , a pressure loss from the inlet of the fuel gas flow path to the resistance part is ΔP _0, and the fuel gas flow path between each single cell The maximum flow resistance variation from the inlet to the resistance portion is (1 + r), the stoichiometric ratio of the fuel gas in the fuel gas flow path having the minimum flow resistance is St ₂ , and the fuel gas flow path from the inlet to the outlet ΔP _c / ΔP ₀ ≧ r / {2 (St ₂ −1) −r (1−L) where L is the ratio of the distance from the inlet of the fuel gas flow path to the resistance portion when the distance is 1. )} Is satisfied.

In another fuel cell stack according to the present invention, the back flow of the fuel off gas between the single cells can be suppressed. In this case, the backflow of impure gas such as N ₂ gas that has permeated from the cathode to the fuel gas flow path is suppressed. As a result, output reduction of the fuel cell stack according to the present invention, catalyst deterioration, and the like can be suppressed.

  The design method according to the present invention includes a flow path of a resistance portion provided in a fuel gas flow path in order to suppress a flow of fuel gas in a fuel cell stack in which a plurality of single cells each having a fuel gas flow path formed are stacked. A design method for designing a resistance, which includes a design step of designing a flow resistance based on a pressure loss variation of a fuel gas flow path of a single cell constituting a fuel cell stack.

In the design method according to the present invention, the flow resistance is designed based on the pressure loss variation of the fuel gas flow path, so that the back flow of the fuel off gas between the single cells can be suppressed. In this case, the backflow of impure gas such as N ₂ gas that has permeated from the cathode to the fuel gas flow path is suppressed. As a result, output reduction of the fuel cell stack according to the present invention, catalyst deterioration, and the like can be suppressed.

In the design step, the pressure loss from the inlet to the outlet of the fuel gas passage is ΔP _c , the pressure loss from the inlet of the fuel gas passage to the resistance portion is ΔP _0, and the resistance from the inlet of the fuel gas passage between each single cell is ΔP _c / ΔP ₀ ≧ r / (2 (2 ()), where the maximum variation in flow resistance to the portion is (1 + r) and the stoichiometric ratio of the fuel gas in the fuel gas flow channel having the minimum flow resistance is St ₂ It may be a step of designing the channel resistance so as to satisfy St ₂ -1)).

The design step is such that the pressure loss from the inlet to the outlet of the fuel gas flow path is ΔP _c , the pressure loss from the inlet of the fuel gas flow path to the resistance portion is ΔP _0, and the flow resistance of the fuel gas flow path between each single cell When the maximum variation is (1 + r) and the stoichiometric ratio of the fuel gas in the fuel gas flow path is St ₂ in other single cells excluding the single cell having the maximum flow path resistance, ΔP _c / ΔP ₀ ≧ r / It may be a step of designing the channel resistance so as to satisfy (2 (St ₂ -1)).

In the design step, the pressure loss from the inlet to the outlet of the fuel gas passage is ΔP _c , the pressure loss from the inlet of the fuel gas passage to the resistance portion is ΔP _0, and the resistance from the inlet of the fuel gas passage between each single cell is The maximum variation in flow resistance to the part is (1 + r), the stoichiometric ratio of the fuel gas in the fuel gas flow path having the minimum flow resistance is St _2, and the distance from the inlet to the outlet of the fuel gas flow path is 1. When the ratio of the distance from the inlet of the fuel gas flow path to the resistance portion is L, ΔP _c / ΔP ₀ ≧ r / {2 (St ₂ −1) −r (1−L)} is satisfied. Thus, the step of designing the flow path resistance may be used.

  The fuel gas channel may be a porous channel. The fuel cell stack may be an anode gas circulation-less fuel cell stack.

  According to the present invention, the backflow of impure gas into the fuel gas channel can be suppressed.

  Hereinafter, the best mode for carrying out the present invention will be described.

  FIG. 1 is a schematic diagram showing an outline of a fuel cell stack 100 according to a first embodiment of the present invention. As shown in FIG. 1, the fuel cell stack 100 has a structure in which a stacked body 110 is sandwiched between an end plate 120a and an end plate 120b. The stacked body 110 has a structure in which a plurality of single cells 130 are stacked. Further, the fuel cell stack 100 is provided with an exhaust valve 140 connected to a fuel gas discharge manifold 41b described later.

  Next, details of the single cell 130 will be described. FIG. 2 is a schematic cross-sectional view of the single cell 130. FIG. 2 shows a case where a plurality of single cells 130 are stacked. As shown in FIG. 2, the single cell 130 has a structure in which a seal gasket-integrated MEA (membrane electrode assembly) 20 is sandwiched between two separators 10. The separator 10 has a structure in which an intermediate plate 12 is sandwiched between a cathode facing plate 11 and an anode facing plate 13. These three plates constituting the separator 10 are joined by hot pressing or the like.

  The seal gasket-integrated MEA 20 includes an MEA 21 and a seal gasket 22. The MEA 21 has a structure in which a catalyst layer and a gas diffusion layer are sequentially formed on both surfaces of an electrolyte membrane having proton conductivity. The catalyst layer is made of a conductive material that supports a catalyst, such as platinum-supported carbon. The gas diffusion layer is made of a conductive material having gas permeability, for example, carbon cloth, carbon paper or the like. In this embodiment, the upper surface side of the MEA 21 functions as an anode, and the lower surface side of the MEA 21 functions as a cathode.

  A porous channel 23 is disposed on the MEA 21. A porous body flow path 24 is disposed under the MEA 21. The porous body channels 23 and 24 are made of a conductive material harder than the gas diffusion layer, and are made of a metal porous body such as a foam metal made of titanium or the like, a metal mesh, or a lath metal. It is preferable that the porous channels 23 and 24 have such strength that the thickness is substantially constant regardless of the presence or absence of dimples in the separator 10. In this case, the porosity hardly changes regardless of the presence or absence of dimples. Further, the surface pressure on the diffusion layer can be made substantially constant in the surface regardless of the presence or absence of dimples. Therefore, since the local compression in the diffusion layer can be reduced, the drainage performance is improved.

  FIG. 3 is a diagram for explaining the details of the separator 10 and the seal gasket-integrated MEA 20. 3A is a schematic plan view of the cathode facing plate 11, FIG. 3B is a schematic plan view of the anode facing plate 13, and FIG. 3C is a schematic plan view of the intermediate plate 12. FIG. 3D is a schematic plan view of the seal gasket-integrated MEA 20.

  The cathode facing plate 11 is a rectangular metal plate. As the metal plate, a plate made of titanium, titanium alloy, stainless steel, or the like that has been subjected to plating treatment for corrosion prevention can be used.

  As shown in FIG. 3A, a portion of the cathode facing plate 11 facing the MEA 21 (hereinafter referred to as a power generation region X) is a plane. A fuel gas supply manifold 41a, a fuel gas discharge manifold 41b, an oxidant gas supply manifold 42a, an oxidant gas discharge manifold 42b, a cooling medium supply manifold 43a, and a cooling medium discharge manifold 43b are formed on the outer peripheral edge of the cathode facing plate 11. Has been. The cathode facing plate 11 has a plurality of oxidant gas supply holes 44a and a plurality of oxidant gas discharge holes 44b. The manifolds and the holes penetrate the cathode facing plate 11 in the thickness direction.

  As shown in FIG. 3B, the anode facing plate 13 is a rectangular metal plate having substantially the same shape as the cathode facing plate 11 and is made of the same material as the cathode facing plate 11. The power generation region X in the anode facing plate 13 is a plane.

  Similar to the cathode facing plate 11, on the outer peripheral edge of the anode facing plate 13, there are a fuel gas supply manifold 41a, a fuel gas discharge manifold 41b, an oxidant gas supply manifold 42a, an oxidant gas discharge manifold 42b, and a cooling medium supply manifold 43a. In addition, a cooling medium discharge manifold 43b is formed. The anode facing plate 13 is formed with a common rail 45a for supplying fuel gas and a common rail 45b for discharging fuel gas. The manifolds and the common rails penetrate the anode facing plate 13 in the thickness direction.

  As shown in FIG. 3C, the intermediate plate 12 is a rectangular metal plate having the same shape as the cathode facing plate 11 and is made of the same material as the cathode facing plate 11. Similar to the cathode facing plate 11, a fuel gas supply manifold 41a, a fuel gas discharge manifold 41b, an oxidant gas supply manifold 42a and an oxidant gas discharge manifold 42b are formed on the outer peripheral edge of the intermediate plate 12.

  The intermediate plate 12 is formed with a plurality of fuel gas supply passages 46a having one end communicating with the fuel gas supply manifold 41a and the other end communicating with the common rail 45a. Similarly, the intermediate plate 12 is formed with a plurality of fuel gas discharge passages 46b having one end communicating with the fuel gas discharge manifold 41b and the other end communicating with the common rail 45b.

  Further, the intermediate plate 12 is formed with a plurality of fuel gas supply passages 46a having one end communicating with the oxidant gas supply manifold 42a and the other end communicating with the oxidant gas supply hole 44a. Similarly, the intermediate plate 12 is formed with a plurality of oxidant gas discharge passages 47b having one end communicating with the oxidant gas discharge manifold 42b and the other end communicating with the oxidant gas discharge hole 44b. Further, the intermediate plate 12 is formed with a plurality of cooling medium flow paths 48 having one end communicating with the cooling medium supply manifold 43a and the other end communicating with the cooling medium discharge manifold 43b. Each flow path penetrates the intermediate plate 12 in the thickness direction.

  As shown in FIG. 3 (d), the seal gasket-integrated MEA 20 has a structure in which a seal gasket 22 is joined to the outer peripheral edge of the MEA 21. The seal gasket 22 is made of a resin material such as silicon rubber, butyl rubber, or fluorine rubber, for example. The seal gasket 22 is manufactured by injection-molding the resin material with the outer peripheral end of the MEA 21 facing the mold cavity. According to this method, the MEA 21 and the seal gasket 22 are joined without a gap. Thereby, leakage from the junction of the cooling medium, the oxidant gas, and the fuel gas can be prevented.

  Similar to the cathode facing plate 11, the seal gasket 22 includes a fuel gas supply manifold 41a, a fuel gas discharge manifold 41b, an oxidant gas supply manifold 42a, an oxidant gas discharge manifold 42b, a cooling medium supply manifold 43a, and a cooling medium discharge manifold. 43b is formed. The seal gasket 22 seals the two separators 10 in contact with the upper surface and the lower surface. The seal gasket 22 seals between the outer periphery of the MEA 21 and the outer periphery of each manifold.

  Next, an outline of the operation of the fuel cell stack 100 during power generation will be described. First, a fuel gas containing hydrogen is supplied to the fuel gas supply manifold 41a. This fuel gas is supplied to the porous body flow path 23 via the fuel gas supply flow path 46a and the common rail 45a. Thereafter, the fuel gas is supplied to the anode side gas diffusion layer of the MEA 21 while flowing through the porous body flow path 23. Hydrogen in the fuel gas is converted into protons in the catalyst layer of the MEA 21. The converted protons conduct through the electrolyte membrane of MEA 21 and reach the cathode catalyst layer.

  On the other hand, the oxidizing gas containing oxygen is supplied to the oxidizing gas supply manifold 42a. This oxidant gas is supplied to the porous body flow path 24 via the oxidant gas supply flow path 47a. Thereafter, the oxidant gas is supplied to the cathode side gas diffusion layer of the MEA 21 while flowing through the porous body flow path 24. In the cathode side catalyst layer of the MEA 21, water is generated and oxygen is generated from oxygen and protons in the oxidant gas. The generated electric power is collected through the separator 10.

  A cooling medium such as cooling water is supplied to the cooling medium supply manifold 43a. This cooling medium flows through the cooling medium flow path 48 to cool the fuel cell stack 100. Thereby, the temperature of the fuel cell stack 100 can be adjusted to an appropriate temperature. The cooling medium flowing through the cooling medium flow path 48 is discharged to the outside through the cooling medium discharge manifold 43b. The oxidant gas that has not been used for power generation is discharged to the outside through the oxidant gas discharge passage 47b and the oxidant gas discharge manifold 42b.

  The fuel gas that has not been used for power generation flows to the common rail 45b, the fuel gas discharge passage 46b, and the fuel gas discharge manifold 41b. The exhaust valve 140 in FIG. 1 is controlled to be closed when the fuel cell stack 100 generates power. In this case, the fuel gas is not discharged to the outside, and is not circulated and supplied to the fuel cell stack 100 again. Thereby, hydrogen contained in fuel gas can be consumed efficiently. However, impure gas such as nitrogen may permeate from the cathode side to the anode side. When such an impure gas concentration becomes high on the anode side, the exhaust valve 140 is controlled to open. Thereby, the impure gas staying on the anode side can be purged. Thus, the fuel cell stack 100 according to the present embodiment is an anode gas circulation-less type.

  Next, the relationship between the common rails 45a and 45b and the porous body channel 23 will be described. FIG. 4A is a schematic diagram showing the relationship between the common rails 45 a and 45 b and the porous body flow path 23. The porous body flow path 23 is provided in the power generation region X shown in FIG. One end of the common rail 45 a is located at a predetermined corner portion of the porous body flow path 23. This one end functions as a fuel gas inlet in the common rail 45a. The common rail 45 a extends from the inlet in the long side direction of the porous body flow path 23. Since the common rail 45a is a space, the flow resistance of the common rail 45a is smaller than the flow resistance of the porous flow path 23.

  Further, the common rail 45b is formed at a position corresponding to the opposite side of the common rail 45a in the porous body flow path 23 so as to extend in the long side direction of the porous body flow path 23. The resistor 25 is connected to the other end of the common rail 45b. The resistance portion 25 communicates with the fuel gas discharge manifold 41b. The resistance portion 25 is made of a porous body, a resin, or the like, and has a flow path resistance higher than that of the porous body flow path 23. The resistance unit 25 may be a stop.

  From the above, the fuel gas flowing into the common rail 45a from the inlet of the common rail 45a flows through the porous body flow path 23, is collected by the common rail 45b, and is discharged from the fuel gas discharge manifold 41b.

  FIG. 4B is a diagram showing flow path resistance, fuel gas pressure, and fuel gas flow rate at a flow path position from the common rail 45a to the fuel gas discharge manifold 41b during power generation. As shown in FIG. 4B, since hydrogen is consumed with power generation, the fuel gas flow rate decreases almost linearly from the common rail 45a toward the fuel gas discharge manifold 41b. On the other hand, the flow path resistance becomes a substantially constant value in the porous body flow path 23 and rapidly increases in the resistance portion 25. Therefore, the fuel gas pressure gradually decreases in the porous body flow path 23 and rapidly decreases in the resistance portion 25. From the above, by arranging the resistance portion 25, the flow of the fuel gas in the porous body flow path 23 is suppressed.

Here, ΔP _c is a cell pressure loss when pure H ₂ gas having a stoichiometric ratio of 1 is caused to flow through the porous body channel 23 during non-power generation. The cell pressure loss refers to a gas pressure loss in the flow path of the fuel gas provided in each cell. The stoichiometric ratio refers to the ratio of the amount of supplied hydrogen gas to the amount of hydrogen gas necessary to realize the target current density. Therefore, when the stoichiometric ratio is 1, all hydrogen is consumed for power generation if the target current density is achieved.

If the fuel gas pressure at the common rail 45a inlet and fuel gas pressure at the _{P in} the fuel gas discharge manifold 41b and _{P out,} [Delta] P _c is expressed by the following equation (1).
ΔP _c = P _in −P _out (1)

Further, the pressure of the fuel gas at the upstream end of the resistance portion 25 and P _2, when the [Delta] P ₀ cell pressure drop from the common rail 45a inlet to the upstream end of the resistance portion 25, [Delta] P ₀ is the following equation (2) It is expressed in
ΔP ₀ = P _in −P ₂ (2)

In this case, the cell pressure loss ΔP (St) during power generation when the stoichiometric ratio is St is expressed by the following equation (3).
ΔP (St) = (St- 1) × ΔP c + ΔP 0/2 (3)

Here, consider a case where two single cells 130 are stacked as shown in FIG. The ratio of the flow resistance of the fuel gas flow path of the single cell 130a to the flow resistance of the fuel gas flow path of the single cell 130b is Rk = (1 + r). That is, it is assumed that the channel resistance of the single cell 130b is smaller than the channel resistance of the single cell 130a. Further, a stoichiometric ratio in the unit cell 130a and 1, the stoichiometric ratio in the unit cell 130b and St _2.

In this case, since ΔP (St ₂ ) = Rk × ΔP (1), the following equations (4) to (6) are derived.
_{(St 2 -1) × ΔP c} + ΔP 0/2 = (1 + r) × ΔP 0/2 (4)
2 (St ₂ −1) × ΔP _c / ΔP ₀ + 1 = 1 + r (5)
ΔP _c / ΔP ₀ = r / (2 (St ₂ −1)) (6)

When it is desired to average stoichiometric ratio St of each single cell 130 to ST ₂ or less, it is necessary to satisfy the following equation (7).
ΔP _c / ΔP ₀ ≧ r / (2 (St ₂ −1)) (7)

In the present embodiment, the flow path resistance of the resistance portion 25 is set in the porous body flow path 23 so as to satisfy the above formula (7). In this case, the backflow of the fuel off gas from the fuel gas discharge manifold 41b to the single cell 130b can be suppressed. Thereby, inflow of N ₂ gas or the like that has permeated from the cathode into the single cell 130 is suppressed. As a result, output reduction of the fuel cell stack 100, catalyst deterioration, and the like can be suppressed.

  The above formula (7) can also be applied when two or more single cells are stacked. In this case, if the maximum flow resistance variation of the fuel gas flow path between the single cells is (1 + r), the flow path resistance of the resistance portion 25 can be set using Equation (7). Here, the maximum flow resistance variation refers to the ratio of the flow resistance having the largest flow resistance difference from the average flow resistance of each cell to the average flow resistance.

Further, the relationship between the average stoichiometric ratio St and St ₂ is expressed by the following formula (8), where n is the number of stacked single cells.
_{St 2 = (St-1)} × n / (n-1) +1 (8)

In the case St <about 1.02 micro discharge, as shown in equation (3), the pressure loss at the time of power generation is considerably smaller than [Delta] P _c. However, at the time of purging during the start-up or power generation is stopped, the flow path resistance of the [Delta] P _c is that according to the flowing gas. Therefore, at the pressure difference ΔP _max (about 100 kPa) at the time of purging, ΔP so that the total gas flow path volume QV (for example, about 5 liters) of the fuel cell stack 100 can be replaced with air with ΔT (for example, about 1 second). _If an upper limit is provided for _c , the following formula (9) is derived.
ΔP _c (flow rate QV / ΔT, air) <ΔP _max (9)

Incidentally, three or more unit cells in the fuel cell stack formed by stacking, or an average stoichiometric ratio of all the cells as St _2.

(Another example of the position of the resistance part)
In FIG. 4, the resistance portion 25 is provided outside the porous channel 23, but may be provided in the porous channel 23. FIG. 6A to FIG. 6F are schematic views showing other examples of the porous channel 23. FIGS. 6A, 6 </ b> C, and 6 </ b> E are schematic plan views of other examples of the porous channel 23. FIG. 6B is a cross-sectional view taken along line AA in FIG. FIG. 6D is a cross-sectional view taken along the line BB in FIG. FIG.6 (f) is CC sectional view taken on the line of FIG.6 (e).

  In FIG. 6A and FIG. 6B, the resistance portion 25 is disposed so as to surround the upstream end portion of the common rail 45b. In FIG. 6C and FIG. 6D, the resistance portion 25 is connected to the upstream end of the common rail 45b. Moreover, in FIG.6 (e) and FIG.6 (f), the resistance part 25 is arrange | positioned in the porous body flow path 23 upstream from the common rail 45b. In the case of FIG. 6A to FIG. 6F, the resistance portion 25 can be formed by injecting resin or the like into the porous body flow path 23.

Assuming that ΔP ₀ is a cell pressure loss when pure H ₂ gas having a stoichiometric ratio of 1 is passed through the porous body flow path 23 during non-power generation before injecting the resistance portion 25, the stoichiometric ratio is being generated at St. The cell pressure loss ΔP (St) is expressed by the following formula (10).
ΔP (St) = (St- 1) × ΔP c + ΔP 0/2 + ΔP c (1-L) / 2 (10)

  In Expression (10), L represents the ratio of the distance from the common rail 45a inlet to the upstream end of the resistance portion 25 when the distance from the common rail 45a inlet to the fuel gas discharge manifold 41b is 1.

In this case, in order to satisfy ΔP (St ₂ ) = Rk × ΔP (1), the following formula (11) needs to be satisfied.
ΔP _c / ΔP ₀ = r / {2 (St ₂ -1) -r (1-L)} (11)

Further, when the average stoichiometric ratio St of each single cell 130 was ST ₂ below, it is necessary to satisfy the following equation (12).
ΔP _c / ΔP ₀ ≧ r / {2 (St ₂ -1) -r (1-L)} (12)

However, in a practical range (L> 0.95, r <0.1), r / {2 (St ₂ -1) -r (1-L)} and r / (2 (St ₂ -1). )) Is approximately 1, so that the following equation (13) should be satisfied regardless of the value of L. The following formula (13) is the same as the above formula (7).
ΔP _c / ΔP ₀ ≧ r / (2 (St ₂ −1)) (13)

  In the present embodiment, a flat separator is used as the separator 10, but is not limited thereto. For example, a press separator may be used as the separator 10. Here, the press separator is a plate-like member having a substantially constant thickness, a convex portion on one surface corresponding to a concave portion on the other surface, and a concave portion on one surface corresponding to a convex portion on the other surface. I mean. The flat separator can be formed, for example, by pressing a substantially flat metal plate such as stainless steel or titanium with a press die. The flat separator may be formed by pressing a conductive material made of conductive particles such as carbon and a binder such as resin.

  In the present embodiment, the inlet of the common rail 45a corresponds to the inlet of the fuel gas passage, and the fuel gas discharge manifold 41b corresponds to the outlet of the fuel gas passage.

It is a schematic diagram which shows the outline of the fuel cell stack which concerns on 1st Example of this invention. It is typical sectional drawing of a single cell. It is a figure for demonstrating the detail of a separator and seal gasket integrated MEA. It is a figure which shows the relationship between a common rail and a porous body flow path. It is a figure which shows the single cell of 2 sheets. It is a schematic diagram which shows the other example of a porous body flow path.

Explanation of symbols

10 Separator 20 Seal gasket integrated MEA
21 MEA
22 Seal gasket 23, 24 Porous flow path 25 Resistance part 41b Fuel gas discharge manifold 45a, 45b Common rail 100 Fuel cell stack 130 Single cell

Claims (11)

A fuel cell stack in which a plurality of single cells each having a fuel gas flow path are stacked,
Each fuel gas flow path is provided with a resistance portion for suppressing the flow of fuel gas,
The pressure loss from the inlet of the fuel gas channel to the outlet is ΔP _c , the pressure loss from the inlet of the fuel gas channel to the resistance portion is ΔP _0, and from the inlet of the fuel gas channel between the single cells to the ΔP _c / ΔP ₀ ≧ r / (, where (1 + r) is the maximum flow resistance variation up to the resistance, and St ₂ is the stoichiometric ratio of the fuel gas in the fuel gas flow path having the minimum flow resistance. 2 (St ₂ -1)). A fuel cell stack in which a plurality of single cells each having a fuel gas flow path are stacked,
Each fuel gas flow path is provided with a resistance portion for suppressing the flow of fuel gas,
The pressure loss from the inlet to the outlet of the fuel gas flow path is ΔP _c , the pressure loss from the inlet of the fuel gas flow path to the resistance portion is ΔP _0, and the flow resistance of the fuel gas flow path between each single cell When the maximum variation is (1 + r) and the stoichiometric ratio of the fuel gas in the fuel gas flow path is St _{2 in} other single cells excluding the single cell having the maximum flow path resistance, ΔP _c / ΔP ₀ ≧ r / (2 (St ₂ -1)) is satisfied, The fuel cell stack characterized by the above-mentioned. A fuel cell stack in which a plurality of single cells each having a fuel gas flow path are stacked,
Each fuel gas flow path is provided with a resistance portion for suppressing the flow of fuel gas,
The pressure loss from the inlet of the fuel gas channel to the outlet is ΔP _c , the pressure loss from the inlet of the fuel gas channel to the resistance portion is ΔP _0, and from the inlet of the fuel gas channel between the single cells to the The maximum variation in flow resistance to the resistance portion is (1 + r), the stoichiometric ratio of the fuel gas in the fuel gas flow channel having the minimum flow resistance is St _2, and the distance from the inlet to the outlet of the fuel gas flow channel ΔP _c / ΔP ₀ ≧ r / {2 (St ₂ −1) −r (1−1) where L is the ratio of the distance from the inlet of the fuel gas flow path to the resistance portion when L)} is satisfied.   The fuel cell stack according to claim 1, wherein the fuel gas channel is a porous channel.   The fuel cell stack according to any one of claims 1 to 4, wherein the fuel cell stack is an anode gas circulation-less fuel cell stack. A design method for designing the flow resistance of a resistance portion provided in the fuel gas flow path in order to suppress the flow of fuel gas in a fuel cell stack in which a plurality of single cells formed with fuel gas flow paths are stacked. There,
A design method comprising: a design step of designing the flow path resistance based on pressure loss variation of the fuel gas flow path of the single cell constituting the fuel cell stack. In the design step, the pressure loss from the inlet to the outlet of the fuel gas flow path is ΔP _c , the pressure loss from the inlet of the fuel gas flow path to the resistance portion is ΔP _0, and the fuel gas flow between the single cells is ΔP _c / ΔP, where (1 + r) is the maximum flow resistance variation from the entrance to the resistance portion and the stoichiometric ratio of the fuel gas in the fuel gas flow path having the minimum flow resistance is St ₂ The design method according to claim 6, wherein the flow path resistance is designed to satisfy ₀ ≧ r / (2 (St ₂ −1)). In the design step, the pressure loss from the inlet to the outlet of the fuel gas flow path is ΔP _c , the pressure loss from the inlet of the fuel gas flow path to the resistance portion is ΔP _0, and the fuel gas flow between the single cells is ΔP _c when the flow path resistance maximum variation of the path is (1 + r) and the stoichiometric ratio of the fuel gas in the fuel gas flow path is St _{2 in} other single cells except the single cell having the maximum flow path resistance. The design method according to claim 6, wherein the flow path resistance is designed to satisfy / ΔP ₀ ≧ r / (2 (St ₂ −1)). In the design step, the pressure loss from the inlet to the outlet of the fuel gas flow path is ΔP _c , the pressure loss from the inlet of the fuel gas flow path to the resistance portion is ΔP _0, and the fuel gas flow between the single cells is The maximum variation in flow path resistance from the path entrance to the resistance portion is (1 + r), the stoichiometric ratio of the fuel gas in the fuel gas flow path having the minimum flow path resistance is St ₂ , and the fuel gas flow path entrance ΔP _c / ΔP ₀ ≧ r / {2 (St ₂ −1), where L is the ratio of the distance from the inlet of the fuel gas flow path to the resistor when the distance from the outlet to the outlet is 1. The design method according to claim 6, wherein the flow path resistance is designed to satisfy −r (1-L)}.   The design method according to claim 6, wherein the fuel gas channel is a porous channel.   The design method according to claim 6, wherein the fuel cell stack is an anode gas circulation-less fuel cell stack.

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