JP2006156411A - Polymer electrolyte fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polymer electrolyte fuel cell with a polymer electrolyte membrane having improved durability while suppressing a flooding phenomenon. <P>SOLUTION: The polymer electrolyte fuel cell comprises cells each composed of a plate anode side separator arranged on one side of a MEA with its front face contacting the anode of the MEA and having a fuel gas flow path formed on the front face for fuel gas to flow therein and a plate cathode side separator 10 arranged with its front face contacting with the cathode of the MEA and having an oxidizing agent gas flow path formed on the front face for oxidizing agent to flow therein, a cell stack having the plurality of stacked cells, and a cooling water flow path 19 formed on the back face of at least one of the anode side separator and the cathode side separator 10 of at least the predetermined cell of the cell stack for cooling water to flow therein. The fuel gas, the oxidizing agent gas and the cooling water flow in the fuel gas flow path, the oxidizing agent gas flow path and the cooling water flow path 19, respectively, without acting counter to the force of gravity. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell used for a portable power source, an electric vehicle power source, a domestic cogeneration system, and the like, and more particularly, to a polymer electrolyte fuel cell using a polymer electrolyte.

  A fuel cell using a polymer electrolyte generates electric power and heat simultaneously by electrochemically reacting a fuel gas containing hydrogen and an oxidant gas containing oxygen such as air. This fuel cell basically includes a polymer electrolyte membrane that selectively transports hydrogen ions and a pair of electrodes formed on both sides of the polymer electrolyte membrane, that is, an anode and a cathode. The electrode is mainly composed of carbon powder carrying a platinum group metal catalyst, and has both a gas permeability and an electronic conductivity formed on the outer surface of the catalyst layer and the catalyst layer formed on the surface of the polymer electrolyte membrane. It consists of a gas diffusion layer.

  The electrodes are formed on both sides of the portion other than the edge of the polymer electrolyte membrane so that the fuel gas and the oxidant gas supplied to the electrode do not leak out or the two kinds of gases are mixed with each other, A gas seal material or a gasket is disposed at the edge of the polymer electrolyte membrane so as to surround each electrode. These gas seal materials and gaskets are assembled in advance by being integrated with the electrode and the polymer electrolyte membrane. This is called MEA (electrolyte membrane electrode assembly). On both sides of the MEA, conductive separators for mechanically fixing the MEA and electrically connecting adjacent MEAs in series with each other are disposed. A gas flow path for supplying reaction gas to the electrode surface and carrying away generated water and surplus gas is formed in a portion of the separator that contacts the MEA. Although the gas flow path can be provided separately from the separator, a method of providing a gas flow path by providing a groove on the surface of the separator is generally used.

  The supply of the reaction gas to the gas flow channel and the discharge of the reaction gas and generated water from the gas flow channel are performed by providing a through-hole called a manifold hole in the separator and communicating the gas flow channel with the manifold hole. The reaction gas is distributed from the manifold hole to each gas flow path. Since the fuel cell generates heat during operation, it is necessary to cool the fuel cell with cooling water or the like in order to maintain the battery in a favorable temperature state. Usually, a cooling unit for flowing cooling water is provided for every 1 to 3 cells. These MEAs, separators, and cooling units are stacked alternately, and after stacking 10 to 200 cells, it is generally sandwiched between end plates via current collector plates and insulating plates and fixed from both ends with fastening rods. This is a structure of a laminated battery.

  Perfluorosulfonic acid-based materials have been used for the polymer electrolyte membrane of this type of battery. Since this polymer electrolyte membrane exhibits ionic conductivity in a state containing moisture, it is usually necessary to humidify the fuel gas or oxidant gas and supply it to the battery. In addition, on the cathode side, water is generated by the reaction, so if gas humidified so that the dew point is higher than the operating temperature of the battery is supplied, dew condensation occurs in the gas flow path inside the battery and inside the electrode, There has been a problem that the battery performance is not stabilized or the performance is lowered due to a phenomenon such as water clogging. Usually, such a phenomenon that the battery performance is deteriorated or the operation is unstable due to excessive wetting is called a flooding phenomenon. On the other hand, when a fuel cell is made into a power generation system, systemization including humidification of a supply gas is necessary. In order to simplify the system and improve system efficiency, it is preferable to reduce the dew point of the supplied humidified gas as much as possible.

  As described above, from the viewpoint of preventing flooding, improving system efficiency, and simplifying the system, the supply gas is usually supplied with humidification so that the dew point is slightly lower than the battery temperature. there were.

  However, in order to improve the performance of the battery, it is necessary to improve the ionic conductivity of the polymer electrolyte membrane. For this purpose, the supply gas is supplied at a humidity close to 100% relative humidity or at a relative humidity of 100% or more. It is preferable. Moreover, it turned out that it is preferable to supply supply gas with high humidification also from a viewpoint of durability of a polymer electrolyte membrane. However, when a gas having a humidity close to 100% relative humidity is to be supplied, the above-described flooding phenomenon is a problem. That is, the flooding phenomenon cannot be suitably prevented by adjusting the humidity of the supply gas.

  On the other hand, in order to avoid the flooding phenomenon, it is known that a method of blowing the condensed water by increasing the flow velocity of the supply gas in the separator flow path portion is known to be effective. However, in order to increase the supply gas flow rate, it is necessary to supply the gas at a high pressure, and the power of auxiliary equipment such as a gas supply blower or a compressor in the case of systemization must be extremely increased. Invite the deterioration. In addition, when the flooding phenomenon occurs on the anode side, the fuel gas is deficient, which is fatal to the battery. This is because when the load current is forcibly taken in the absence of fuel gas, the carbon carrying the anode catalyst reacts with the water in the atmosphere to produce electrons and protons in the absence of fuel. By doing. As a result, the elution of carbon from the catalyst layer destroys the anode catalyst layer.

  In addition, in a system equipped with a laminated battery, it is indispensable not only to operate the battery under rated output conditions but also to be able to perform a low-load operation with a reduced output according to the power demand in consideration of merchantability. In low-load operation, in order to maintain efficiency, it is necessary to make the utilization rate of fuel gas and oxidant gas the same as in rated operation. That is, when the load is reduced to ½ with respect to the rated operation, for example, if the flow rate of the fuel gas or oxidant gas is not reduced to about ½, excess fuel gas or oxidant gas should be used. Therefore, the power generation efficiency decreases. However, if a low load operation is performed with a constant gas utilization rate, the gas flow rate in the gas flow path decreases, and the condensed water and product water cannot be discharged outside the separator, resulting in the flooding phenomenon described above. There are problems that the battery performance deteriorates or becomes unstable.

In addition, it is known that such a flooding phenomenon is more likely to occur when there is a portion that flows against the gravity in the gas flow path, and condensed water or generated water stays in that portion. As a countermeasure against this, a method of flowing an oxidant gas or a fuel gas in a direction that does not oppose gravity has been proposed (see Patent Document 1 and Patent Document 2). According to this method, by causing the oxidant gas or the fuel gas to flow in a direction that does not oppose gravity, the condensed water and generated water can be discharged smoothly, and the occurrence of flooding can be suppressed.
JP-A-11-233126 JP 2001-068131 A

  By the way, in general, the oxidant gas and the fuel gas increase in relative humidity because the gas amount decreases and the generated water increases toward the downstream from the cell inlet toward the outlet. Moreover, when relative humidity exceeds 100%, it becomes condensed water and a moisture content increases. On the other hand, the temperature of the cooling water is lowest at the entrance to the cell and becomes higher toward the exit. As described above, the supply gas to the battery needs to be supplied in a humidified state close to 100% relative humidity. Normally, this cooling water is flowed to the main surface opposite to the main surface through which the reaction gas of the separator flows, thereby cooling the electrode portion that generates heat through the separator. Here, if the cooling water is made to flow in the opposite direction to the reaction gas, it is necessary to supply the reaction gas humidified to 100% relative humidity with respect to the high-temperature cooling water. In addition, since the supplied large amount of humidified water becomes all condensed water in the downstream portion of the reaction gas where the temperature of the cooling water is low, flooding due to water clogging is likely to occur. Furthermore, in the actual cogeneration system, when the supply gas is humidified using the cooling water, it is impossible to increase the humidification temperature to the same temperature as the outlet temperature of the cooling water. As a result, since the relative humidity of the reaction gas cannot be supplied at 100%, the polymer electrolyte membrane dries at the gas inlet and the durability deteriorates.

  Further, when this cooling water is supplied to the stack from the upper side in the gravity direction and flows downward, the cooling water is branched from the cooling water inlet manifold hole to each cooling water flow path according to the gravity. As the cell is closer to the inlet pipe, more cooling water flows, and the uniformity of the cooling water deteriorates. In particular, during partial load operation, the amount of heat generated by the power generation reaction decreases, so it is necessary to reduce the flow rate of the cooling water in order to keep the battery temperature constant, thereby further degrading the evenness of the cooling water. This causes a problem.

  The present invention has been made to solve the above-described problems, and improves the toughness against the flooding phenomenon and improves the durability of the fuel cell by suppressing the dryness of the electrolyte membrane at the gas inlet portion. It is a first object of the present invention to provide a polymer electrolyte fuel cell that can be used.

  It is a second object of the present invention to provide a polymer electrolyte fuel cell that can improve the distribution of cooling water.

  In order to solve the above problems, a polymer electrolyte fuel cell according to the present invention includes a MEA having a hydrogen ion conductive polymer electrolyte membrane, an anode and a cathode sandwiching the polymer electrolyte membrane, and a front surface facing the anode. A plate-like anode-side separator disposed on one side of the MEA so as to be in contact with the fuel gas flow path through which fuel gas flows on the front side; and the other side of the MEA so that the front side is in contact with the cathode A plate-like cathode-side separator having an oxidant gas flow path in which an oxidant gas flows on the front surface, a cell stack in which a plurality of the cells are stacked, and at least one of the cell stacks A cooling water flow path through which cooling water formed on at least one of the anode side cathode and the cathode side separator of a predetermined cell flows. For example, the fuel gas, the oxidizing gas, and the cooling water, respectively, the fuel gas flow field, the oxidant gas flow path, and flows so as not defying gravity in the cooling water flow path. The fuel gas, the oxidant gas, and the cooling water may flow against the gravity in the manifold portion.

  The fuel gas flow path, the oxidant gas flow path, and the cooling water flow path may each be formed to have a horizontal or downward gradient toward the downstream.

  At least one of the fuel gas flow path, the oxidant gas flow path, and the cooling water flow path may be substantially configured by a horizontal portion and a vertical portion.

  In the cathode side separator, an upstream portion of the oxidant gas flow channel may be located in the vicinity of the inlet of the cooling water flow channel.

  In the anode separator, an upstream portion of the fuel gas passage may be located in the vicinity of the inlet of the cooling water passage.

  In the cathode side separator, the cooling water channel and the oxidant gas channel may be formed so as to substantially overlap each other when viewed in the thickness direction.

  In the anode-side separator or the cathode-side separator, an inlet manifold hole for supplying cooling water to the cooling water flow path is formed by a locally approaching portion of an inner peripheral surface that penetrates the separator in the thickness direction and faces the separator. The first portion located on one side of the throttle portion communicates with the cooling water supply pipe, and the second portion located on the other side of the throttle portion is connected to the cooling water flow path. You may communicate.

  In the anode-side separator or the cathode-side separator, an inlet manifold hole for supplying cooling water to the cooling water passage is provided so as to penetrate the separator in the thickness direction and have a step in the circumferential direction at the lower part of the inner peripheral surface. The first portion located below the step may communicate with the cooling water supply pipe, and the second portion located above the step may communicate with the cooling water flow path.

  The present invention has the configuration as described above. First, in a polymer electrolyte fuel cell, the toughness against flooding phenomenon is improved and the occurrence of dryness of the electrolyte membrane at the gas inlet portion is suppressed. As a result, the durability of the fuel cell can be improved.

  Second, in the polymer electrolyte fuel cell, there is an effect that the distribution of cooling water can be improved.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
(Concept of invention)
First, the concept of the present invention will be described. The present inventor promotes the smooth discharge of condensed water by directing the flow in the plane parallel to the extending surface of the oxidant gas, fuel gas, and cooling water in a direction that does not oppose gravity, and the flooding phenomenon. It has been found that the durability of the fuel cell can be improved by improving the toughness of the fuel cell and suppressing the dryness of the electrolyte membrane at the gas inlet. The first aspect of the present invention was made based on this finding.
Further, according to the second aspect of the present invention, the distribution of the cooling water can be ensured by providing a throttle or a step in the cooling water inlet manifold hole.

  In order to improve the commerciality of the fuel cell power generation system, it is desired that the load on the fuel cell according to the power demand can be changed without reducing the power generation efficiency. To that end, when the load is increased with respect to the rated output, the flow rate of the fuel gas and the oxidant gas is increased to a flow rate corresponding to the load, and when the load is decreased with respect to the rated output, it is commensurate with it. It is necessary to operate by reducing the flow rate of the fuel gas and the oxidant gas to the flow rate. Usually, the gas flow path provided in the conductive separator used in the fuel cell is designed to have the most suitable gas flow rate at the rated output. Therefore, when the power load is increased, the gas flow rate of the flow path increases as the gas flow rate increases, and when the power load is decreased, the gas flow rate of the flow path increases as the gas flow rate decreases. Decrease. When the gas flow rate in the flow path increases, the pressure loss of the supply gas increases, and although the power generation efficiency decreases slightly due to an increase in auxiliary power, the gas flow rate in the flow path increases. Rather, condensed water and product water in the flow path can be removed efficiently, and no flooding phenomenon occurs.

  However, when the power load is reduced, the gas flow rate in the flow path also decreases as the gas flow rate decreases. When the gas flow rate in the flow path decreases, depending on the degree of decrease in the gas flow rate, it becomes difficult to efficiently remove condensed water and generated water in the gas flow path of the separator, and a flooding phenomenon occurs. At this time, if the flow rate of the supply gas is not decreased even though the power load is decreased, the ratio of the auxiliary power to the power generation output is relatively increased, and the power generation efficiency of the entire power generation system is decreased. At this time, in order to keep the temperature of the fuel cell constant, it is necessary to change the flow rate of the cooling water in accordance with the increase or decrease of the power load. The isotropic distribution of the cooling water is impaired.

  The present invention prevents the flooding by facilitating smooth discharge of condensed water by flowing all the flow of the oxidant gas flow path, the fuel gas flow path, and the cooling water flow path in a direction that does not oppose gravity. Eliminates drying of the electrolyte membrane at the inlet and improves durability. For example, when the ratio between the maximum load power generation output and the minimum load power generation output is 4 to 1, the flow rate becomes 1/4 when the gas utilization rate is constant and the gas amount is decreased. In the conventional separator, when the gas flow rate decreases, the condensed water cannot be discharged against the gravity, and a flooding phenomenon occurs. On the other hand, in the present invention, since the oxidant gas and the fuel gas always flow in a direction that does not oppose gravity, it has been found that the condensed water can be smoothly discharged and no flooding occurs. Further, the present inventors have found that the durability of the electrolyte membrane can be improved by matching the gas inlet portion where the relative humidity is the lowest with the inlet portion of the cooling water when viewed from the thickness direction of the separator, thereby eliminating the dryness of the electrolyte membrane.

  Furthermore, it has been found that by providing a throttle at the cooling water inlet manifold hole, the cooling water supplied to the cell stack can be improved in the uniformity of the cooling water when it is distributed to a plurality of cooling water flow paths in the cell stack. It was. Further, cooling is performed by positioning the inlet of each flow channel for distributing the cooling water from the cooling water inlet manifold hole in the gravity direction higher than the position where the cooling water is supplied to the cooling water inlet manifold hole. It has been found that even when the flow rate of water is reduced, it is possible to ensure even distribution and a more stable operation is possible.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Embodiment 1
12 is a perspective view showing a schematic configuration of a polymer electrolyte fuel cell (hereinafter simply referred to as a fuel cell) according to Embodiment 1 of the present invention, and FIG. 13 is a cross-sectional view taken along the XIII-XIII plane of FIG. It is.

  In FIG. 12, the vertical direction in the fuel cell is represented as the vertical direction in the figure. This also applies to FIGS. 1 to 6 described later.

As shown in FIG. 12, the fuel cell of the present embodiment has a cell stack 1.
The cell stack 1 includes a cell laminate 101 in which cells 2 having a plate-like overall shape are laminated in the thickness direction, and first and second end plates 3A and 3B arranged at both ends of the cell laminate 101. And a fastener (not shown) that fastens the cell laminate 2 and the first and second end plates 3 </ b> A and 3 </ b> B in the stacking direction of the cells 2. The first and second end plates 3A and 3B are provided with current collecting terminals, respectively, but are not shown.
The plate-like cell 2 extends parallel to the vertical plane, and therefore the stacking direction of the cells 2 is a horizontal direction.

An oxidant gas supply manifold 4 is formed on an upper portion of one side portion (hereinafter referred to as a first side portion) of the cell stack 101 so as to penetrate the cell stack 101 in the stacking direction. One end of the oxidant gas supply manifold 4 communicates with a through hole formed in the first end plate 3A, and an oxidant gas supply pipe 51 is connected to the through hole. The other end of the oxidant gas supply manifold 4 is closed by a second end plate 3B. In addition, an oxidant gas discharge manifold 7 is formed below the other side portion (hereinafter, second side portion) of the cell stack 101 so as to penetrate the cell stack 101 in the stacking direction. One end of the oxidant gas supply manifold 7 is closed by the first end plate 3A. The other end of the oxidant gas discharge manifold 7 communicates with a through hole formed in the second end plate 3B, and an oxidant gas discharge pipe 52 is connected to the through hole.
A fuel gas supply manifold 5 is formed above the second side portion of the cell stack 101 so as to penetrate the cell stack 101 in the stacking direction. One end of the fuel gas supply manifold 5 communicates with a through hole formed in the first end plate 3A, and a fuel gas supply pipe 53 is connected to the through hole. The other end of the fuel gas supply manifold 5 is closed by a second end plate 3B. Further, a fuel gas discharge manifold 6 is formed below the first side portion of the cell stack 101 so as to penetrate the cell stack 101 in the stacking direction. One end of the fuel gas discharge manifold 6 is closed by the first end plate 3A. The other end of the fuel gas supply manifold 5 communicates with a through hole formed in the second end plate 3B, and a fuel gas discharge pipe 54 is connected to the through hole.

  A cooling water supply manifold 8 is formed inside the upper portion of the oxidant gas supply manifold 4 so as to penetrate the cell stack 101 in the stacking direction. One end of the cooling water supply manifold 8 communicates with a through hole formed in the first end plate 3A, and a cooling water supply pipe 30 is connected to the through hole. The other end of the cooling water supply manifold 8 is closed by the second end plate 3B. A cooling water discharge manifold 9 is formed inside the lower portion of the oxidant gas discharge manifold 7 so as to penetrate the cell stack 101 in the stacking direction. One end of the cooling water discharge manifold 9 is closed by the first end plate 3A. The other end of the cooling water discharge manifold 9 communicates with a through hole formed in the second end plate 3B, and a cooling water discharge pipe 31 is connected to the through hole. Here, the cooling water supply manifold 8 and the cooling water discharge manifold 9 have a cross-sectional shape that is a long hole shape that is long in the horizontal direction (a shape in which two opposite sides of the rectangle are replaced with two semicircular sides). ing.

  As shown in FIG. 13, the cell 2 includes a plate-like MEA 43 and a cathode-side separator 10 and an anode-side separator 20 that are disposed so as to be in contact with both main surfaces of the MA 43. In the cells 2 and 2 adjacent to each other, the cells 2 are stacked such that the back surface of the cathode-side separator 10 of one cell 2 and the back surface of the anode-side separator 20 of the other cell 2 are in contact with each other. The MEA 43, the cathode-side separator 10, and the anode-side separator 20 are formed in the same shape (here, a rectangle) having the same size. The MEA 43, the cathode-side separator 10, and the anode-side separator 20 are formed at predetermined locations corresponding to each other through the oxidant inlet manifold hole, the oxidant outlet manifold hole, and the fuel inlet. A manifold hole, a fuel outlet manifold hole, a cooling water inlet manifold hole, and a cooling water outlet manifold hole are formed, and the oxidizing agent inlets of the MEA 43, the cathode side separator 10, and the anode side separator 20 in all the cells 2 are formed. A manifold hole, an oxidant outlet manifold hole, a fuel inlet manifold hole, a fuel outlet manifold hole, a cooling water inlet manifold hole, and a cooling water outlet manifold hole are connected to each other to form an oxidant supply manifold 4 and an oxidant. Discharge manifold 7 and fuel supply manifold 5 Fuel discharge manifold 6, the cooling water supply in manifold 8, and the cooling water discharge manifold 9 is formed respectively.

  An oxidant gas flow path 17 and a cooling water flow path 19 are formed on the front and back surfaces of the cathode separator 10, respectively. As will be described later, the oxidant gas flow path 17 is formed so as to connect the oxidant gas inlet manifold hole and the oxidant gas outlet manifold hole, and the cooling water flow path 19 is formed as described later. The manifold hole and the cooling water outlet manifold hole are formed so as to communicate with each other. And the cathode side separator 10 is arrange | positioned so that a front may contact MEA43.

  A fuel gas flow path 28 and a cooling water flow path 29 are formed on the front and back surfaces of the anode-side separator 20, respectively. As will be described later, the fuel gas flow path 19 is formed so as to connect the fuel gas inlet manifold hole and the fuel gas outlet manifold hole, and the cooling water flow path 29 is connected to the cooling water inlet manifold hole, as will be described later. It is formed so as to communicate with the outlet manifold hole of the cooling water. And the anode side separator 20 is arrange | positioned so that a front may contact MEA43.

  Each flow path 17, 19, 28, 29 is configured by a groove formed on the main surface of the cathode separator 10 or the anode separator 20. In addition, each flow path 17, 19, 28, 29 is composed of two flow paths in FIG. 13, but may be composed of a large number of flow paths.

Further, the cooling water flow path 19 of the adjacent cathode side separator 10 and the cooling water flow path 29 of the anode side separator 20 are formed so as to be joined (joined) to each other when the cells 2 are stacked, and one of them is one. A cooling water flow path is formed.
Further, on the back surface of the cathode-side separator 10 and the back surface of the anode-side separator 20, an inlet manifold hole and an outlet manifold hole, a cooling water flow path, an oxidant inlet manifold hole, an oxidant outlet manifold hole, An O-ring housing groove is formed so as to surround the fuel inlet manifold hole and the fuel outlet manifold hole, and O-rings 47 are respectively disposed in the grooves. As a result, the manifold holes and the like are sealed with each other.

  The MEA 43 includes a polymer electrolyte membrane 41, a cathode 42A, an anode 42B, and a pair of gaskets 46. Then, a cathode 42A and an anode 42B are formed on both sides of the portion other than the edge of the polymer electrolyte membrane 41, respectively, and a gasket 46 is provided on both sides of the edge of the polymer electrolyte membrane 41 so as to surround the cathode 42A and the anode 42B, respectively. Has been placed. The pair of gaskets 46, the cathode 42A, the anode 42B, and the polymer electrolyte membrane 41 are integrated with each other.

  Further, the cathode 42A, the anode 42B, the region where the oxidant gas flow channel 17 is formed in the cathode side separator 10 and the region where the cooling water flow channel 19 is formed, and the fuel gas flow channel 28 in the anode side separator 20 are formed. The region and the region in which the cooling water flow path 29 is formed are disposed so as to substantially overlap each other when viewed from the stacking direction of the cells 2.

  Next, the cathode side separator and the anode side separator will be described in detail.

  1 is a front view of the cathode side separator, FIG. 2 is a rear view thereof, FIG. 3 is a front view of the anode side separator, and FIG. 4 is a rear view thereof.

  As shown in FIG. 1, the cathode separator 10 includes an oxidant gas inlet manifold hole 11 and an outlet manifold hole 13, a fuel gas inlet manifold hole 12 and an outlet manifold hole 14, and an inlet manifold hole 15 and an outlet manifold for cooling water. It has a hole 16. The separator 10 further has a gas flow path 17 that communicates the manifold holes 11 and 13 on the surface facing the cathode, and a flow path 19 that communicates the manifold holes 15 and 16 of the cooling water on the back surface. .

  In FIG. 1, the inlet manifold hole 11 for the oxidant gas is provided in the upper part of one side of the separator 10 (the left side in the drawing: hereinafter referred to as the first side), and the outlet manifold hole 13 is formed in the separator 10. It is provided in the lower part of the other side part (the side part on the right side of the drawing: hereinafter referred to as the second side part). The fuel gas inlet manifold hole 12 is provided in the upper portion of the second side portion of the separator 10, and the outlet manifold hole 14 is provided in the lower portion of the first side portion of the separator 10. The cooling water inlet manifold hole 15 is provided inside the upper part of the oxidant gas inlet manifold hole 11, and the outlet manifold hole 16 is provided inside the lower part of the oxidant gas outlet manifold hole 13. The cooling water manifold holes 15 and 16 are formed in a long hole shape that is long in the horizontal direction.

  In this embodiment, the oxidant gas channel 17 is composed of two channels. Of course, any number of channels can be used. Each flow path is substantially composed of a horizontal portion 17a extending in the horizontal direction and a vertical portion 17b extending in the vertical direction. Specifically, each flow path of the oxidant gas flow path 17 extends horizontally from the upper part of the oxidant gas inlet manifold hole 11 to the second side of the separator 10, and extends downward from there. Extends horizontally to the first side of the separator 10 and extends downwardly there. From there, the above-mentioned extending pattern is repeated twice and extends horizontally from the reaching point to the lower part of the outlet manifold hole 13 for the oxidant gas. And the part extended horizontally of each flow path forms the horizontal part 17a, and the part extended below forms the vertical part 17b. As a result, in the oxidant gas flow path 17, the oxidant gas flows without countering gravity while meandering so as to alternately pass through the horizontal portions 17a and the vertical portions 17b, and as a result, flooding is suppressed. .

  Here, each flow path is composed of a horizontal portion 17a and a vertical portion 17b. However, as long as each flow channel is formed to be horizontal or downwardly inclined (including vertical) in the gas flow direction. Good. However, if each channel is composed of the horizontal portion 17a and the vertical portion 17b, the oxidant gas channel 17 can be formed with high density.

  In FIG. 2, the cooling water channel 19 is composed of two channels. Each flow path is substantially constituted by a horizontal portion 19a extending in the horizontal direction and a vertical portion 19b extending in the vertical direction. Specifically, each flow path of the cooling water flow path 19 extends downward from the end of the cooling water inlet manifold hole 15 closer to the oxidant gas inlet manifold hole 11, and from there, the separator 10. Extends horizontally to the second side (left side of the drawing), extends a distance below it, and extends horizontally from there to the first side (right side of the drawing). From there, the above extension pattern is repeated twice and a half, and extends downward from the reaching point to the end of the coolant outlet manifold hole 16 closer to the oxidant gas outlet manifold hole 13. ing. And the part extended horizontally of each flow path forms the horizontal part 19a, and the part extended below forms the vertical part 19b. Thereby, in the cooling water channel 19, the cooling water flows without countering gravity while meandering so as to alternately pass through the horizontal portions 19a and the vertical portions 19b.

  What is important here is the following point. That is, the cooling water inlet manifold hole 15 and the oxidizing gas inlet manifold hole 11 are provided close to each other, and the cooling water outlet manifold hole 16 and the oxidizing gas outlet manifold hole 13 are provided close to each other. Further, the cooling water channel 18 is formed so as to substantially overlap the oxidant gas channel 17 when viewed from the thickness direction of the separator 10, and as a result, the cooling water and the oxidant gas are substantially sandwiched between the separator 10. In the same direction. By comprising in this way, seeing from the thickness direction of the separator 10, since the oxidant gas inlet part where the relative humidity becomes the lowest and the inlet part of the cooling water substantially coincide, the drying of the polymer electrolyte membrane is eliminated. As a result, the durability of the polymer electrolyte membrane can be improved.

  In addition, although each flow path is substantially comprised here with the horizontal part 19a and the vertical part 19b here, it should just be formed so that it may become horizontal or a downward slope toward the flow direction of cooling water. . However, if each flow path is composed of the horizontal part 19a and the vertical part 19b, the cooling water flow path 19 can be formed with high density.

  The anode separator 20 has an inlet manifold hole 21 and an outlet manifold hole 23 for oxidant gas, an inlet manifold hole 22 and an outlet manifold hole 24 for fuel gas, and an inlet manifold hole 25 and an outlet manifold hole 26 for cooling water. The separator 20 further has a gas flow path 28 that communicates the manifold holes 22 and 24 on the surface facing the anode, and a flow path 29 that communicates the manifold holes 25 and 26 of the cooling water on the back surface. .

  In FIG. 3, the inlet manifold hole 21 for the oxidant gas is provided in the upper part of one side portion of the separator 20 (the right side portion in the drawing: hereinafter referred to as the first side portion). It is provided in the lower part of the other side part (the side part on the left side of the drawing: hereinafter referred to as the second side part). The fuel gas inlet manifold hole 22 is provided in the upper portion of the second side portion of the separator 20, and the outlet manifold hole 24 is provided in the lower portion of the first side portion of the separator 20. The cooling water inlet manifold hole 25 is provided inside the upper part of the oxidant gas inlet manifold hole 21, and the outlet manifold hole 26 is provided inside the lower part of the oxidant gas outlet manifold hole 23. The cooling water manifold holes 25 and 26 are formed in a long hole shape that is long in the horizontal direction.

  The fuel gas channel 28 is composed of two channels in the present embodiment. Each flow path is substantially composed of a horizontal portion 28a extending in the horizontal direction and a vertical portion 28b extending in the vertical direction. Specifically, each flow path of the fuel gas flow path 28 extends horizontally from the upper part of the fuel gas inlet manifold hole 22 to the first side of the separator 20, extends from there downward, and then horizontally. Extending horizontally to the second side of the separator 20 and extending downwardly therefrom. From there, the above-mentioned extending pattern is repeated twice and extends horizontally from the reaching point to the lower part of the outlet manifold hole 24 for the fuel gas. And the part extended horizontally of each flow path forms the horizontal part 28a, and the part extended below forms the vertical part 28b. Thereby, in the fuel gas flow path 28, the fuel gas flows without countering gravity while meandering so as to alternately pass through the horizontal portions 28a and the vertical portions 28b, and as a result, flooding is suppressed.

  Here, each flow path is substantially composed of a horizontal portion 28a and a vertical portion 28b, but is formed to have a horizontal or downward gradient (including vertical) in the gas flow direction. It only has to be. However, if each channel is composed of the horizontal portion 28a and the vertical portion 28b, the fuel gas channel 28 can be formed with high density.

  In FIG. 4, the cooling water flow path 29 is formed so that the right and left in the drawing are opposite to the cooling water flow path 19 formed on the back surface of the cathode separator 10 in FIG. That is, each flow path is substantially composed of a horizontal portion 29a extending in the horizontal direction and a vertical portion 29b extending in the vertical direction. Specifically, each flow path of the cooling water flow path 29 extends downward from the end of the cooling water inlet manifold hole 25 closer to the oxidant gas inlet manifold hole 21 by a distance from the separator 20. Extends horizontally to the second side (the side on the right side of the drawing), extends downwardly therefrom, and then extends horizontally to the first side (the side on the left side of the drawing). From there, the above extension pattern is repeated twice and a half, and extends downward from the reaching point to the end of the coolant outlet manifold hole 26 closer to the oxidant gas outlet manifold hole 23. ing. And the part extended horizontally of each flow path forms the horizontal part 29a, and the part extended below forms the vertical part 29b. Thereby, in the cooling water flow path 29, the cooling water flows without repelling gravity while meandering so as to alternately pass through the horizontal portions 29a and the vertical portions 29b.

  The important points here are as follows. That is, both the cooling water inlet manifold hole 25 and the fuel gas inlet manifold hole 22 are provided in the upper part of the separator 20, and both the cooling water outlet manifold hole 26 and the fuel gas outlet manifold hole 24 are provided in the lower part of the separator 20. And the cooling water passage 29 is formed so as to substantially overlap the fuel gas passage 28 when viewed from the thickness direction of the separator 20, and as a result, the cooling water and the oxidant gas are in the horizontal direction. Although they flow in opposite directions with the separator 20 in between, they flow in the same direction from top to bottom as a whole in the vertical direction. By configuring in this way, the upstream part of the fuel gas flow path 28 where the relative humidity is lowest is located in the upper part where the cooling water inlet part is provided and the temperature is lowest in the vertical direction of the separator 20. This contributes to eliminating the dryness of the polymer electrolyte membrane and, in turn, contributes to improving the durability of the polymer electrolyte membrane.

  In addition, although each flow path is substantially comprised here with the horizontal part 29a and the vertical part 29b here, it should just be formed so that it may become horizontal or a downward slope toward the flow direction of cooling water. . However, if each flow path is composed of the horizontal part 29a and the vertical part 29b, the cooling water flow path 29 can be formed with high density.

  As described above, a cell is configured by sandwiching the MEA between the cathode-side separator 10 and the anode-side separator 20. Accordingly, between adjacent cells, the cathode side separator 10 and the anode side separator 20 are arranged with their cooling water flow paths 19 and 29 facing each other to constitute a cooling unit. When providing a cooling unit for each of a plurality of cells, instead of the composite separator as described above, a single separator in which one surface serves as a cathode side separator and the other surface serves as an anode side separator is appropriately used.

  Next, the flow operation of the fuel gas, the oxidant gas, and the cooling water of the fuel cell configured as described above will be described.

  1 to 6, 12, and 14, the fuel gas is supplied to the fuel gas supply manifold 5 of the cell stack 1 through the fuel gas supply pipe 43. The supplied fuel gas flows from the fuel gas supply manifold 5 into the inlet manifold hole 22 of each cell 2 and flows through the fuel gas flow path 28. During this period, the fuel gas consumed by reacting with the oxidant gas via the anode, the polymer electrolyte membrane, and the cathode flows out from the outlet manifold hole 24 to the fuel gas discharge manifold 6 as an off-gas, It is discharged from the cell stack 1 through the fuel gas discharge pipe 44.

  On the other hand, the oxidant gas is supplied to the oxidant gas supply manifold 8 of the cell stack 1 through the oxidant gas supply pipe 41. The supplied oxidant gas flows from the oxidant gas supply manifold 4 into the inlet manifold hole 11 of each cell 2 and flows through the oxidant gas flow path 17. During this time, the oxidant gas consumed by reacting with the fuel gas via the cathode, the polymer electrolyte membrane, and the anode flows out from the outlet manifold hole 13 to the oxidant gas discharge manifold 7 and is oxidized. It is discharged from the cell stack 1 through the agent gas discharge pipe 42.

  Further, the cooling water is supplied to the cooling water supply manifold 8 of the cell stack 1 through the cooling water supply pipe 30. The supplied cooling water flows from the cooling water supply manifold 8 into the inlet manifold holes 15 and 25 of each cell 2 and flows through the cooling water flow paths 19 and 29. During this time, the cathode and the anode are cooled via the cathode separator 10 and the anode separator 20, and heat is recovered from these, and flows out from the outlet manifold holes 16 and 26 to the cooling water discharge manifold 9, and the cooling water discharge pipe 31 is discharged from the cell stack 1.

  In this process, the fuel gas and the oxidant gas flow through the fuel gas flow path 28 and the oxidant gas flow path 17 so as not to oppose gravity, thereby preventing flooding.

Moreover, in each separator 10 and 20, since the upstream part of the fuel gas flow path 28 or the oxidant gas flow path 17 where relative humidity becomes the lowest is located near the inlet of the cooling water, the polymer electrolyte Drying of the membrane is prevented.
<< Embodiment 2 >>
FIG. 5 is a rear view of the anode separator of the fuel cell according to Embodiment 2 of the present invention. 5, the same reference numerals as those in FIG. 4 denote the same or corresponding parts.

In the present embodiment, in the cell stack 1 of the first embodiment shown in FIG. 12, the cooling water supply manifold 8 has the same cross-sectional shape as the cooling water inlet manifold hole 25A of the anode separator 20A shown in FIG. ing.
As shown in FIG. 5, the anode side separator 20 </ b> A has a cooling water inlet manifold hole 25 </ b> A divided into a first portion 31 a and a second portion 31 b by a throttle portion 32. Although not shown, the cathode side separator and the cooling water inlet manifold hole of the MEA are also formed in the same shape as the cooling water inlet manifold hole 25A of the anode side separator 20A. The first portion 31 a of the inlet manifold hole 25 A is where the cooling water supplied from the cooling water supply pipe 30 to the cooling water supply manifold 8 circulates, and the second portion 31 b is supplied to the cooling water passage 29. Is about to supply. The other points of the present embodiment are the same as those of the first embodiment.

Referring to FIGS. 12 and 5, in the fuel cell of the present embodiment configured as described above, the cooling water is supplied from the cooling water supply pipe 30 to the first inlet manifold hole 25 </ b> A of the cooling water supply manifold 8. It is supplied to the part corresponding to the part 31a. The supplied cooling water is distributed to each cell 2 while flowing in the stacking direction of the cell stack 1. Here, when there is no throttle portion 32 in the inlet manifold hole 25 </ b> A, the cooling water tends to flow more as the cell is closer to the cooling water supply pipe 30 due to the influence of gravity. In the present embodiment, due to the effect of the throttle portion 32, the cooling water supplied to the inlet manifold hole 25A for the cooling water is once filled in the upstream side of the throttle portion 32, that is, in the first portion 31a. Is supplied to the cooling water passage 29 of each cell 2 via the portion 31b. Therefore, the cooling water can be evenly distributed from the cell 2 closest to the cooling water supply pipe 30 to the cell 2 farthest. Here, the cross-sectional area in the direction in which the cooling water of the throttle portion 32 passes is preferably designed in the range of 1 to 10 times the total value of the cross-sectional areas of the respective flow paths of the cooling water flow path 29. In addition, the direction through which the cooling water of the throttle portion 32 passes is the direction of the arrow X in FIG. 5, that is, the horizontal direction in the extending surface of the cell 2 (and thus the separator 20A).
<< Embodiment 3 >>
FIG. 6 is a rear view of the anode separator of the fuel cell according to Embodiment 3 of the present invention. 6, the same reference numerals as those in FIG. 4 denote the same or corresponding parts.

  In the present embodiment, in the cell stack 1 of the first embodiment shown in FIG. 12, the cooling water supply manifold 8 has the same cross-sectional shape as the cooling water inlet manifold hole 25B of the anode separator 20B shown in FIG. ing.

In this separator 20B, the cooling water inlet manifold hole 25B
The bottom is configured in two steps so as to have a first portion 41a having a deep bottom and a second portion 41b having a shallow bottom. In other words, the inlet manifold hole 25B has a step 47c in the circumferential direction at the lower part of the inner peripheral surface, and the first portion 41a located below the step 47c and the second portion 41b located above the step 57c. Are formed. Although not shown, the cathode side separator and the cooling water inlet manifold hole of the MEA are also formed in the same shape as the cooling water inlet manifold hole 25B of the anode side separator 20B. The first portion 41 a of the inlet manifold hole 25 B is where the cooling water supplied from the cooling water supply pipe 30 to the cooling water supply manifold 8 circulates, and the second portion 41 b passes to the cooling water channel 29. The cooling water is being supplied.

  In the separator 20B, the second portion 41b for distributing the cooling water from the cooling water inlet manifold hole 25B to each flow path is perpendicular to the first portion 41a to which the cooling water is supplied from the cooling water supply pipe 30. It is formed at a high position in the direction. By forming the cooling water inlet manifold hole 25B in such a shape, the cooling water filled in the first portion 41a on the upstream side of the second portion 41b becomes the extended surface of the separator 20B in the second portion 41b. Since the flow velocity is increased in the horizontal direction in the interior and distributed to each flow path so as to maintain the flow velocity, the uniformity of the cooling water can be further improved. Further, when the throttle 32 is simply provided on the inlet side of the second portion 31b as in the second embodiment, the throttle effect is reduced when the flow rate of the cooling water is reduced during partial load operation. However, there is a risk that the iso-distribution of cooling water will deteriorate. However, in the present embodiment, the bottom of the second portion 41b located on the downstream side is shallower than the bottom of the first portion 41a located on the upstream side, so even when the flow rate of the cooling water is small, Since the cooling water supplied from the cooling water supply pipe 30 once accumulates in the first portion 41 a and then flows to the second portion 41 b communicating with each flow path of the cooling water flow path 29, the equal distribution is achieved. It can be secured. Further, when foreign matter or the like is mixed in the cooling water, it precipitates in the first portion 41a, so that it can be prevented from flowing into the cooling water passage 29, and cooling water clogging due to foreign matter or the like can be prevented.

Examples of the present invention will be described below.
Example 1
Acetylene black-based carbon powder (DENKA BLACK FX-35 manufactured by Denki Kagaku Co., Ltd.) and platinum particles having an average particle diameter of about 30 mm were supported by 25% by weight. This is the cathode catalyst. Further, platinum-ruthenium alloy (Pt: Ru = 1: 1 (weight ratio)) particles having an average particle diameter of about 30 mm are supported on acetylene black carbon powder (DENKA BLACK FX-35 manufactured by Electrochemical Co., Ltd.) at 25% by weight. I let you. This is the anode catalyst. These catalyst powder isopropanol dispersions were mixed with perfluorocarbonsulfonic acid powder ethyl alcohol dispersion (Flemion FSS-1 manufactured by Asahi Glass Co., Ltd.) to obtain a paste. Using these pastes as raw materials, an electrode catalyst layer was formed on one surface of a carbon non-woven fabric (TGP-H-090 manufactured by Toray Industries, Inc.) each having a thickness of 250 μm. Amount of platinum contained in the catalyst layer of the thus formed electrode is 0.3 mg / cm ^2, the amount of perfluorocarbon sulfonic acid was 1.2 mg / cm ^2.

  These electrodes have the same configuration except for the catalyst material for both the cathode and the anode. These electrodes are hot-pressed so that the printed catalyst layer is in contact with the electrolyte membrane side on both sides of the center of a proton conductive polymer electrolyte membrane (NAFION 122 manufactured by DuPont, USA) having an area slightly larger than the electrode. Joined. In addition, the periphery of the polymer electrolyte membrane exposed on the outer periphery of the electrode is sandwiched between gaskets made of a 250 μm-thick fluororubber (Aflas (registered trademark) manufactured by Asahi Glass Co., Ltd.) and bonded and integrated by hot pressing. It was. Thus, an electrolyte membrane electrode assembly (MEA) was produced. As the proton conductive polymer electrolyte membrane, a perfluorocarbon sulfonic acid thinned to a thickness of 30 μm was used.

In this example, the conductive separator having the structure shown in Embodiment Mode 1 was used. In the figure, the direction in which the fuel cell with the separators stacked is installed in the actual operation and is upward with respect to gravity. In this conductive separator, a gas flow path and a manifold hole were formed on an isotropic graphite plate having a thickness of 3 mm by machining. The groove widths of the gas flow paths 17 and 28 were 2 mm, the depth was 1 mm, and the width between the flow paths was 1 mm, each having a two-pass flow path configuration. The cooling water flow path is the same as the gas flow path except that the groove depth is 0.5 mm. The rated operating conditions of this battery are a fuel utilization rate of 75%, an oxygen utilization rate of 40%, and a current density of 0.3 A / cm ² .

50 cells having the MEA sandwiched between the cathode side separator and the anode side separator as described above were stacked. Between adjacent cells, a flow path of cooling water is formed by both separator plates. The cell laminate was sandwiched between stainless steel end plates via a copper current collector plate with gold plating on the surface and an insulating plate made of polyphenylene sulfide, and both end plates were fastened with fastening rods. The fastening pressure was 10 kgf / cm ² per electrode area. Also, during operation, the laminated battery was installed so that the upper part of the separator shown in the figure was on top.

The fuel cell of this example produced in this way was maintained at 70 ° C., and the fuel gas (80% hydrogen gas / 20% carbon dioxide / 10 ppm carbon monoxide) humidified and heated so that the anode had a dew point of 70 ° C. Were supplied to the cathode with air that was humidified and heated to a dew point of 70 ° C. Were evaluated voltage characteristics - current This battery by changing the current density from the current density 0.075A / cm ² which is 25% of the low load up to 0.3 A / cm ² as a rated load of rated. However, the utilization rate during the test was equivalent to the rated conditions. The result is shown in FIG. FIG. 7 also shows the characteristics of the fuel cell of the comparative example. In the fuel cell of the comparative example, the inlet / outlet of the cooling water was reversed from that in Example 1, and the gas was humidified to a relative humidity of 100% at the inlet. From the figure, in the fuel cell of this example, the fuel cell of the comparative example did not generate flooding even in the vicinity of 0.075 A / cm ² where the operation was difficult due to the occurrence of flooding due to the decrease in gas flow rate, It can be seen that stable operation is possible. In this embodiment, the cooling unit is provided between the anode-side separator and the cathode-side separator of each adjacent cell, but the same effect can be obtained even if the cooling unit is arranged for each of a plurality of cells.
Example 2
In this example, the separator described in Embodiment 2 was used. The cross-sectional area of the throttle portion 32 in the direction in which the cooling water passes is designed in a range of 1 to 10 times the total cross-sectional area of the cooling water flow path on each cooling surface. In this embodiment, since the total cross-sectional area of the two cooling water flow paths is 4 mm 2, the throttle area 32 is designed to have a cross-sectional area of 4 to 40 mm 2.

The voltage of each cell was measured when the fuel cell was operated at the rated load under the operating conditions shown in Example 1. The result is shown in FIG. FIG. 8 also shows the voltage of each cell of the fuel cell of Example 1. Here, the cooling water is supplied from the cell number 1 side, passes through the manifold and the cooling water flow path, and is discharged to the cell number 50 side. It can be seen that the fuel cell of Example 1 has a high voltage value on the inlet side of the cooling water and decreases as it approaches the outlet. This is because the flow rate of the cooling water became non-uniform, so that a cell having a low temperature and a cell having a high temperature were formed. On the other hand, in the fuel cell of the present example, since the cooling water is evenly distributed, the temperature distribution is uniform and the cell voltage is uniform. Further, FIG. 9 shows the result of comparison after these fuel cells have been operated for 1000 hours. From FIG. 9, it can be seen that in the battery of Example 1, the cell voltage deterioration rate near the outlet of the cooling water is large, whereas in the battery of this example, no extreme deterioration is observed across all the cells. The deterioration of the cell voltage is considered to be caused by the deterioration of the electrolyte membrane due to the increase in the temperature of the cell where the flow rate of the cooling water is reduced. Therefore, it can be seen that the improvement in the uniformity of the cooling water according to the present example is effective in suppressing the deterioration of durability.
Example 3
In this example, the separator of Embodiment 3 was used. The cross-sectional area of the throttle portion on the inlet side of the portion 41b communicating with the flow path of the inlet manifold hole 25B was designed in the same manner as in the second embodiment.

  When this fuel cell was operated under the operating conditions shown in Example 1 and at a rated ¼ load, the voltage of each cell was measured when the cooling water was reduced to ¼ of the rated flow rate. The result is shown in FIG. FIG. 10 also shows the voltage of each cell of the fuel cell shown in Example 2. Here, the cooling water is supplied from the cell number 1 side, passes through the manifold and the cooling water flow path, and is discharged to the cell number 50 side. From FIG. 10, it can be seen that both the battery of Example 2 and the present example can be operated stably even at 1/4 load operation. Further, in the battery of Example 2, when the flow rate of the cooling water is reduced to ¼, the uniformity of the cooling water is deteriorated, and the voltage variation for each cell tends to increase slightly. I understand. On the other hand, in the battery of this example, it can be seen that the cell voltage is kept uniform even though the flow rate of the cooling water is reduced. In the inlet manifold hole 25B, the cooling water is once accumulated in the first portion 41a on the upstream side and then supplied to the flow path 29 via the second portion 41b on the downstream side. This is thought to be due to improved uniformity when the amount of water is low.

  FIG. 11 shows the results of comparing the voltages between cells after these batteries were operated for 1000 hours under low-load operation conditions. From FIG. 11, it can be seen that in the battery of Example 2, the cell voltage deterioration rate near the outlet of the cooling water is slightly large, whereas in the battery of this example, the cell voltage decrease rate is uniform. . The deterioration of the cell voltage is considered to be caused by the deterioration of the electrolyte membrane due to the increase in the temperature of the cell where the flow rate of the cooling water is reduced. It can be seen that the improvement in the uniformity of the cooling water according to the present example is also effective in suppressing the deterioration of durability. In particular, it can be seen that the manifold shape as in the present embodiment is effective for a system in which the operation time is long by reducing the flow rate of the cooling water during low-load operation.

  As described above, according to the present invention, smooth flow of condensed water is promoted by reducing the flow of oxidant gas, fuel gas, and cooling water in the separator in a direction that does not oppose gravity. Even at times, flooding does not occur, high-efficiency and stable operation is possible, and drying of the electrolyte membrane at the gas inlet is eliminated, and durability can be improved.

  In addition, by providing a restriction at the inlet manifold hole of the cooling water, it is possible to improve the uniformity of the cooling water when stacking the cells, and to reduce the temperature distribution between the cells. Can do. Furthermore, since no high-temperature cell is generated, deterioration in durability can be reduced.

  Furthermore, by connecting the connecting portion for distributing the cooling water from the cooling water inlet manifold hole to each flow path at a position higher in the gravity direction than the position for supplying the cooling water to the cooling water inlet manifold hole. Even when the flow rate of the cooling water is reduced during low-load operation, it is possible to ensure equidistribution and suppress an increase in voltage variation due to an increase in temperature distribution.

  The polymer electrolyte fuel cell of the present invention is useful as a fuel cell for use in portable power supplies, electric vehicle power supplies, domestic cogeneration systems, and the like.

It is a front view of the cathode side separator used for the fuel cell of Embodiment 1 of this invention. It is a rear view of a cathode side separator similarly. It is a front view of the anode side separator used for the fuel cell of Embodiment 1 of this invention. It is a back view of an anode side separator similarly. It is a rear view of the anode side separator used for the fuel cell of Embodiment 2 of this invention. It is a rear view of the anode side separator used for the fuel cell of Embodiment 3 of this invention. It is a figure which shows the current-voltage characteristic of the fuel cell of Example 1 and Comparative Example 1 of this invention. It is a figure which shows the relationship between the cell number and cell voltage of the fuel cell of Example 1 and Example 2 of this invention. It is a figure which shows the relationship between the cell number after the endurance test of the fuel cell of Example 1 and Example 2 of this invention, and a cell voltage. It is a figure which shows the relationship between the cell number and cell voltage of the fuel cell of Example 2 and Example 3 of this invention. It is a figure which shows the relationship between the cell number and the cell voltage after the endurance test of the fuel cell of Example 2 and Example 3 of this invention. 1 is a perspective view showing a schematic configuration of a polymer electrolyte fuel cell according to Embodiment 1 of the present invention. It is sectional drawing along the XIII-XIII plane of FIG.

Explanation of symbols

1 cell stack 2 cell 3A, 3B end plate 4 oxidant gas supply manifold 5 fuel gas supply manifold 6 fuel gas discharge manifold 7 oxidant gas discharge manifold 8 cooling water supply manifold 9 cooling water discharge manifold 10 cathode side separator 11, 21 oxidation Agent gas inlet manifold hole 13, 23 Oxidant gas outlet manifold hole 17 Oxidant gas flow path 20 Anode side separator 12, 22 Fuel gas inlet manifold hole 14, 24 Fuel gas outlet manifold hole 15, 25, 25A 25B Cooling water inlet manifold hole 16, 26 Cooling water outlet manifold hole 19, 29 Cooling water flow path 28 Fuel gas flow path 30 Cooling water supply piping 31a First part 31b Second part 32 Restriction part 41a First part 41b second part 42A cathode 42B anode 43 MEA
46 Gasket 47c Step
48 O-ring 49 Polymer electrolyte membrane 51 Oxidant gas supply pipe 52 Oxidant gas discharge pipe 53 Fuel gas supply pipe 54 Fuel gas discharge pipe 55 Cooling water discharge pipe

Claims (2)

An MEA having a hydrogen ion conductive polymer electrolyte membrane and an anode and a cathode sandwiching the polymer electrolyte membrane, and disposed on one side of the MEA so that the front is in contact with the anode. A plate-like anode-side separator formed with a flowing fuel gas channel, and an oxidant gas channel that is arranged on the other side of the MEA so that the front surface is in contact with the cathode and through which the oxidant gas flows are formed on the front surface. A cell having a plate-like cathode-side separator formed;
A cell stack in which a plurality of the cells are stacked;
A cooling water flow path through which cooling water formed on at least one of the anode side separator and the cathode side separator of at least a predetermined cell of the cell stack flows.
The fuel gas, the oxidant gas, and the cooling water flow so as not to oppose gravity in the fuel gas flow path, the oxidant gas flow path, and the cooling water flow path, respectively.
In the anode-side separator or the cathode-side separator, an inlet manifold hole for supplying cooling water to the cooling water flow path is formed by a locally approaching portion of an inner peripheral surface that penetrates the separator in the thickness direction and faces the separator. The first portion located on one side of the throttle portion communicates with the cooling water supply pipe, and the second portion located on the other side of the throttle portion is connected to the cooling water flow path. A polymer electrolyte fuel cell in communication. An MEA having a hydrogen ion conductive polymer electrolyte membrane and an anode and a cathode sandwiching the polymer electrolyte membrane, and disposed on one side of the MEA so that the front is in contact with the anode. A plate-like anode-side separator in which a flowing fuel gas channel is formed and an oxidant gas channel that is arranged on the other side of the MEA so that the front surface is in contact with the cathode and through which the oxidant gas flows are formed on the front surface A cell having a plate-like cathode-side separator formed;
A cell stack in which a plurality of the cells are stacked;
A cooling water flow path through which cooling water formed on at least one of the anode side separator and the cathode side separator of at least a predetermined cell of the cell stack flows.
The fuel gas, the oxidant gas, and the cooling water flow so as not to oppose gravity in the fuel gas flow path, the oxidant gas flow path, and the cooling water flow path, respectively.
In the anode-side separator or the cathode-side separator, an inlet manifold hole for supplying cooling water to the cooling water flow path is provided so as to penetrate the separator in the thickness direction and have a step in the circumferential direction at the lower part of the inner peripheral surface. A polymer electrolyte fuel, wherein a first portion located below the step communicates with a cooling water supply pipe, and a second portion located above the step communicates with the cooling water flow path battery.

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