JP2007179973A - Polymer electrolyte fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polymer electrolyte fuel cell in which flooding is certainly prevented while sufficiently suppressing deterioration of a polymer electrolyte membrane. <P>SOLUTION: The fuel cell has a lamination of an element composed of a polymer electrolyte membrane, an anode and an anode which are electrodes arranged on both sides of the polymer electrolyte membrane, an anode side separator which has a fuel gas passage to supply and exhaust a fuel gas to and from the anode, and a cathode side separator which has an oxidant gas passage to supply and exhaust an oxidant gas to and from the cathode. When the fuel cell is operated under a condition in which dew condensation is generated at least in one of the fuel gas passage or the oxidizer gas passage, and with a fuel utilization rate of 60% or more, an oxidizer utilization rate of 40%-80%, and a current density of 0.15 A/cm<SP>2</SP>-0.3 A/cm<SP>2</SP>, a gas flow velocity at the exit of the fuel gas passage becomes 1.8 m/s-4.1 m/s and the gas flow velocity at the exit of the oxidizer gas passage becomes 2.8 m/s-7.7 m/s. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

  A typical fuel cell is a polymer electrolyte fuel cell. In this polymer electrolyte fuel cell, an anode and a cathode are formed with a polymer electrolyte membrane interposed therebetween, and a fuel gas containing hydrogen and an oxidant gas containing oxygen such as air (hereinafter referred to as air) are respectively formed on the anode and the cathode. The fuel gas and the oxidant gas may be collectively referred to as the reaction gas). Then, at the anode, electrons are released from hydrogen atoms in the fuel gas by an electrode reaction to generate hydrogen ions, and these electrons reach the cathode through an external circuit (load). On the other hand, hydrogen ions pass through the polymer electrolyte membrane and reach the cathode. Then, at the cathode, hydrogen ions, electrons, and oxygen in the oxidant gas are combined to generate water. In this reaction, electric power and heat are generated simultaneously.

  By the way, perfluorocarbon sulfonic acid-based materials are used for the polymer electrolyte membrane. Since this polymer electrolyte membrane exhibits ionic conductivity in a state containing moisture, the reaction gas is usually humidified and supplied to the fuel cell.

  However, since water is produced at the cathode, flooding may occur if the reaction gas is excessively humidified. On the other hand, 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, it is preferable to supply the reaction gas with humidification so as to have a relative humidity of 100%. When a reaction gas having a dew point below the operating temperature of the fuel cell is supplied, the perfluorocarbon sulfonic acid electrolyte is decomposed and fluoride ions are eluted from the polymer electrolyte membrane, thereby degrading the polymer electrolyte membrane. Turned out to be.

  Therefore, in order to suppress deterioration of the polymer electrolyte membrane and improve the life of the fuel cell, operation is performed by supplying a reaction gas having a dew point at the same temperature as the cell temperature while preventing flooding (so-called “so-called”). Full humidification operation) has been attempted (see, for example, Non-Patent Document 1).

In addition, each cell has a different gas flow path structure and / or electrode structure, and the reaction gas with the same amount of humidification etc. is distributed to each cell, thereby preventing deterioration of the polymer electrolyte membrane and preventing flooding. 2. Description of the Related Art A fuel cell system designed to prevent this is known (see, for example, Patent Document 1).
Proceedings of the 8th Fuel Cell Symposium Lecture, pages 61 to 64 (refer to the operating conditions described in the captions of FIG. 3 and FIG. 4 in particular) Japanese Patent No. 3596332

  However, the technology of Non-Patent Document 1 has not yet sufficiently suppressed the deterioration of the polymer electrolyte membrane, and has not been able to sufficiently improve the life of the fuel cell. In addition, if humidification is increased to suppress deterioration, flooding occurs, which makes it impossible to operate the fuel cell itself.

  Moreover, in the fuel cell system of patent document 1, it is necessary to provide a different gas flow path structure and / or electrode structure for every single cell, and a structure will become complicated.

  The present invention has been made to solve such problems, and it is possible to reliably prevent flooding while sufficiently suppressing deterioration of a polymer electrolyte membrane of a polymer electrolyte fuel cell based on a simple configuration. An object of the present invention is to provide a possible polymer electrolyte fuel cell.

In order to solve the above problems, a polymer electrolyte fuel cell of the present invention includes a polymer electrolyte membrane, an anode that is an electrode disposed on one surface of the polymer electrolyte membrane, and a polymer electrolyte membrane. An anode as an electrode disposed on the other surface; an anode separator having a fuel gas flow path for supplying and discharging fuel gas to the anode; and an oxidant gas flow path for supplying and discharging oxidant gas to the cathode. A polymer electrolyte fuel that is configured by laminating unit components composed of a cathode separator, and is operated under a condition in which condensed water is generated in at least a part of the fuel gas channel or the oxidant gas channel a battery, fuel utilization of 60% or more, 40% or more and 80% or less oxidizing agent utilization, the field current density is operating at a range of 0.15A ^/ cm ² ~0.3A ^/ cm 2 Further, the gas flow velocity Va at the outlet of the fuel gas flow path is 1.8 m / s or more and 4.1 m / s or less, and the gas flow velocity Vc at the outlet of the oxidant gas flow path is 2.8 m / s or more and 7 or less. 0.7 m / s or less.

  In such a configuration, since the moisture and temperature of the gas flow path are conditions under which dew condensation water is generated, sufficient moisture can be supplied to the polymer electrolyte membrane of the polymer electrolyte fuel cell, and deterioration of the membrane can be sufficiently suppressed. On the other hand, since the flow velocity is in an appropriate range, flooding does not occur even if water droplets derived from condensed water are generated in the fuel gas channel or the oxidant gas channel. Therefore, flooding can be reliably prevented while sufficiently suppressing deterioration of the polymer electrolyte membrane based on a simple configuration.

The polymer electrolyte fuel cell power generation system of the present invention includes the polymer electrolyte fuel cell, a fuel gas supply device that supplies fuel gas to the polymer electrolyte fuel cell, and the polymer electrolyte fuel. An oxidant gas supply device that supplies an oxidant gas to the battery, and a control device, wherein the control device is configured to generate condensed water in at least one of the fuel gas channel and the oxidant gas channel. , When operating so that the fuel utilization rate is 60% or more, the oxidant utilization rate is 40% or more and 80% or less, and the current density is in the range of 0.15 A / cm ^{2 to} 0.3 A / cm ^2. The fuel gas supply device is controlled so that the gas flow velocity Va at the outlet of the fuel gas flow path is in the range of 1.8 m / s to 4.1 m / s, and the gas at the outlet of the oxidant gas flow path Flow velocity Vc is 2.8m Controlling said oxidant gas supply device so as to fall within the following ranges above and 7.7 m / s s.

  In such a configuration, since the flow velocity is actively controlled to an appropriate range, flooding can be more reliably prevented.

  In the polymer electrolyte fuel cell, the thermodynamic condition for generating dewed water is operated so as to satisfy the entire fuel gas flow path, and the gas flow rate Va at the outlet of the fuel gas flow path is Sa is the sum of the gas channel cross-sectional areas of the part where the downstream side of the fuel gas channel communicating with the outlet manifold of the side separator intersects the peripheral edge of the power generation region, and the anode outlet dry base calculated from the fuel utilization rate is unused The total gas flow rate of the fuel gas flow rate and the saturated water vapor amount at the anode outlet temperature may be Qa, and may be obtained by the formula Va = Qa / Sa.

  Alternatively, in the polymer electrolyte fuel cell, the thermodynamic condition in which condensed water is generated operates so as to satisfy the entire oxidant gas flow path, and the gas flow velocity Vc at the outlet of the oxidant gas flow path is , Sc is the sum of the gas channel cross-sectional areas of the part where the downstream side of the oxidant gas channel communicating with the outlet manifold of the cathode separator intersects the peripheral edge of the power generation region, and the cathode outlet dryness calculated from the oxidant utilization rate The total gas flow rate of the base unused oxidant gas flow rate and the saturated water vapor amount at the cathode outlet temperature may be defined as Qc, and may be obtained by the formula Vc = Qc / Sc.

  In such a configuration, the amount of water vapor can be determined on the basis of the outlet temperature even when the conditions under which condensed water is generated are achieved on the entire surface of the electrode.

  In the polymer electrolyte fuel cell, the thermodynamic condition for generating dew condensation water is operated so that at least a part of the fuel gas flow path is satisfied, and the gas flow rate Va at the outlet of the fuel gas flow path is , Sa is the sum of the gas flow path cross-sectional areas of the portion where the downstream side of the fuel gas flow path communicating with the outlet manifold of the anode separator intersects the peripheral edge of the power generation region, and the dry base of the anode outlet calculated from the fuel utilization rate The total gas flow rate of the unused fuel gas flow rate and the gas flow rate when the total water amount supplied to the anode is calculated as steam may be Qa, and may be obtained by the formula Va = Qa / Sa.

  Alternatively, in the polymer electrolyte fuel cell, the gas flow rate at the outlet of the oxidant gas flow channel is operated so that a thermodynamic condition in which condensed water is generated is satisfied by at least a part of the oxidant gas flow channel. Vc is the cathode outlet calculated from Sc, the sum of the gas channel cross-sectional areas of the portion where the downstream side of the oxidant gas channel communicating with the outlet manifold of the cathode separator intersects the peripheral edge of the power generation region, and the oxidant utilization rate The total gas flow rate of the dry base unused oxidant gas flow rate, the gas flow rate when the total water amount supplied to the cathode is calculated as water vapor, and the gas flow rate when the total water amount generated by the cell reaction is calculated as water vapor May be determined by the equation Vc = Qc / Sc.

  In such a configuration, the gas flow rate can be obtained based on the parameter of the supplied gas instead of the outlet temperature.

  The polymer electrolyte fuel cell includes a cooling fluid path that flows through the inside of the fuel cell, a cooling fluid supply device that supplies the cooling fluid to the cooling fluid path, and a control device, the control device comprising: When the power generation is performed, a temperature obtained by converting the total water amount at the inlet of at least one of the fuel gas and the oxidant gas into a dew point (hereinafter referred to as an inlet dew point converted temperature) is represented by T1, and the inlet of the cooling fluid When the temperature (hereinafter referred to as the cooling fluid inlet temperature) is expressed by T2, the cooling fluid supply device may be controlled so as to satisfy the condition of T1 ≧ T2 + 1 ° C.

  In such a configuration, deterioration of the polymer electrolyte membrane can be more reliably prevented by more appropriately controlling the moisture and temperature of the gas flowing inside the fuel cell.

  The polymer electrolyte fuel cell may operate so that the thermodynamic conditions for generating dew condensation water are satisfied over the entire surface of the anode and the cathode.

  In such a configuration, since the condition for generating dew condensation water on the front surfaces of the anode and the cathode is satisfied, it is possible to supply sufficient water to the polymer electrolyte membrane. Therefore, deterioration of the polymer electrolyte membrane can be prevented more reliably.

  In the polymer electrolyte fuel cell, the pressure loss of at least one of the supply gas on the anode side and the cathode side may be 2 kPa or more and 10 kPa or less.

  In such a configuration, flooding can be more reliably prevented by appropriately controlling the pressure loss of the supply gas.

  The present invention is configured as described above, and in a polymer electrolyte fuel cell, flooding is reliably prevented while sufficiently suppressing deterioration of the polymer electrolyte membrane of the polymer electrolyte fuel cell based on a simple configuration. There is an effect that can be.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a block diagram schematically showing a configuration of a polymer electrolyte fuel cell power generation system according to Embodiment 1 of the present invention.

  A polymer electrolyte fuel cell power generation system (hereinafter simply referred to as a fuel cell power generation system) according to the present embodiment includes a polymer electrolyte fuel cell (hereinafter simply referred to as a fuel cell) 101. A fuel gas supply device 102 is connected to a fuel gas inlet 403 for supplying fuel gas to the anode of the fuel cell 101 via a fuel gas supply channel 109. The fuel gas supply device 102 supplies fuel gas to the anode of the fuel cell 101. As the fuel gas, hydrogen gas, a reformed gas obtained by reforming a hydrocarbon gas, or the like is used. In the present embodiment, the fuel gas supply device 102 is constituted by a hydrogen generator that generates a reformed gas as a fuel gas from a raw material gas. The hydrogen generator has a booster pump on the raw material supply side, for example, so that the pressure loss and the supply amount can be adjusted. Here, natural gas is used as the raw material gas.

  An oxidant gas supply device 103 is connected to an oxidant gas inlet 404 for supplying an oxidant gas to the cathode of the fuel cell 101 via an oxidant gas supply channel 107. The oxidant gas supply device 103 supplies oxidant gas to the cathode of the fuel cell 101. Here, air is used as the oxidant gas. The oxidant gas supply device 103 is configured by an air blower in the present embodiment. The fuel gas and the oxidant gas supplied to the anode and cathode of the fuel cell 101 chemically react there, and electric power and heat (hereinafter referred to as exhaust heat) are generated by this chemical reaction. A fuel gas outlet (not shown in FIG. 1) for discharging the fuel gas from the anode of the fuel cell 101 is connected to a fuel gas discharge channel 110, and the surplus that did not contribute to the above-described chemical reaction. The fuel gas is discharged from the anode to the fuel gas discharge channel 110 and appropriately processed. For example, surplus fuel gas discharged to the fuel gas discharge channel 110 is used as fuel for heating the reforming unit of the hydrogen generator constituting the fuel gas supply device 102, or is burned by a dedicated burner. Or, it is appropriately diluted and released into the atmosphere.

  Further, an oxidant gas discharge channel 111 is connected to an oxidant gas outlet (not shown in FIG. 1) for discharging the oxidant gas from the cathode of the fuel cell 101, contributing to the above-described chemical reaction. The excess oxidant gas that has not been discharged is discharged from the cathode into the atmosphere through the oxidant gas discharge channel 111.

  On the other hand, in this fuel cell power generation system 100, a cooling water circulation passage 112 is formed as a cooling fluid circulation passage so as to pass through the fuel cell 101. Water (hereinafter referred to as cooling water) is circulated through the cooling water circulation passage 112 as a cooling fluid. For example, an antifreeze may be used as the cooling fluid. A radiator 105 and a circulation pump 106 are disposed in the cooling water circulation passage 112. The cooling water circulation channel 112, the radiator 105, and the circulation pump 106 constitute a cooling system 104. The heat radiating device 105 releases the heat transmitted from the fuel cell 101 to the cooling water from the cooling water. For example, the heat dissipation device 105 receives exhaust heat from the cooling water and uses the exhaust heat, or a fin It is comprised with the cooling device etc. which have the cooling water flow path which has the formed road wall, and the air blower which blows on this fin. In this cooling system 104, the cooling water is circulated by the circulation pump 106 in the direction of the arrow in FIG. 1 through the cooling water circulation passage 112, so that the exhaust heat received by the cooling water from the fuel cell 101 is released by the heat dissipation device 105. To do. Thereby, the fuel cell 101 is cooled. In this case, the heat dissipation device 105 can adjust the heat dissipation amount per unit flow rate of the cooling water, while the cooling water circulation pump 106 can adjust the flow rate of the cooling water. Therefore, each of the heat radiating device 105 and the cooling water circulation pump 106 can determine the heat radiation amount of the cooling water, and each of these functions as a temperature adjusting means for the cooling water.

  Further, the fuel cell power generation system 100 includes an anode side total heat exchanger 117 and a cathode side total heat exchanger 118.

  The anode-side total heat exchanger 117 includes a supply-side fuel gas channel 117a, a discharge-side fuel gas channel 117b, and a cooling water channel 117c. The gas flowing through the supply-side fuel gas flow path 117a and the gas flowing through the discharge-side fuel gas flow path 117b are formed so as to be capable of total heat exchange. Specifically, a part of the supply-side fuel gas channel 117a and a part of the discharge-side fuel gas channel 117b are formed adjacent to each other across the total heat exchange membrane. As the total heat exchange membrane, for example, a solid polymer electrolyte membrane used in the fuel cell 101 is used. Further, the gas after the total heat exchange flowing through the supply side fuel gas channel 117a is formed so that it can simply exchange heat with the cooling water flowing through the cooling water channel 117c. The supply side fuel gas channel 117a is connected to the fuel gas supply channel 109 so as to be inserted in the middle of the fuel gas supply channel 109, and the discharge side fuel gas channel 117b is connected to the fuel gas discharge channel 110. It is connected to the fuel gas discharge flow path 110 so as to be inserted in the middle. Further, a part of the cooling water circulation channel 112 is configured by two branch channels 112 a and 112 b (here, a branching ratio of 1: 1), and the cooling water channel 117 c is one of the branch channels 112 a of the cooling water circulation channel 112. It is connected to the branch channel 112a so as to be inserted in the middle.

  As a result, the fuel gas flowing out from the fuel gas supply device 102 is humidified and heated by the fuel gas discharged from the fuel cell 101 in the anode-side total heat exchanger 117, and further receives exhaust heat from the fuel cell 101 and rises. The fuel gas is heated with warm cooling water, and thereby has a predetermined dew point converted temperature described later. The fuel gas having the predetermined dew point conversion temperature is supplied to the anode through the fuel gas inlet 403 of the fuel cell 101.

  On the other hand, the cathode-side total heat exchanger 118 has a supply-side oxidant gas channel 118a, a discharge-side oxidant gas channel 118b, and a cooling water channel 118c formed therein. The gas flowing through the supply-side oxidant gas flow path 118a and the gas flowing through the discharge-side oxidant gas flow path 118b are formed so as to be capable of total heat exchange. Specifically, a part of the supply-side oxidant gas flow path 118a and a part of the discharge-side oxidant gas flow path 118b are formed so as to be adjacent to each other across the total heat exchange membrane. As the total heat exchange membrane, for example, a solid polymer electrolyte membrane used in the fuel cell 101 is used. Further, the gas after the total heat exchange flowing through the supply side oxidant gas flow path 118a is formed so as to be able to exchange total heat with the cooling water flowing through the cooling water flow path 118c. The supply-side oxidant gas flow path 118a is connected to the oxidant gas supply flow path 107 so as to be inserted in the middle of the oxidant gas supply flow path 107, and the discharge-side oxidant gas flow path 118b is connected to the oxidant gas flow path. It is connected to the oxidant gas discharge channel 111 so as to be inserted in the middle of the gas discharge channel 111, and the cooling water channel 118 c is inserted in the middle of the other branch channel 112 b of the cooling water circulation channel 112. And connected to the branch channel 112b.

  As a result, the oxidant gas flowing out from the oxidant gas supply device 103 is humidified and heated by the oxidant gas discharged from the fuel cell 101 in the cathode-side total heat exchanger 118, and further exhaust heat is discharged from the fuel cell 101. It is humidified and heated by the cooling water that has been received and heated up, and thereby becomes an oxidant gas having a predetermined dew point conversion temperature described later. The oxidant gas having the predetermined dew point conversion temperature is supplied to the cathode through the oxidant gas inlet 404 of the fuel cell 101.

  Since the utilization rate of the fuel gas is high, the exhaust fuel gas contains a large amount of dew condensation water, and the supplied fuel gas totally exchanged with the exhaust fuel gas also contains a lot of water. Therefore, even if the supplied fuel gas is simply subjected to heat exchange with the exhaust cooling water, the heating capacity of the exhaust cooling water does not decrease. On the other hand, since the utilization rate of the oxidant gas is low, the exhaust oxidant gas has a small amount of water, and the supplied oxidant gas totally exchanged with the exhaust oxidant gas also has a small amount of water. However, since the supplied oxidant gas is totally exchanged with the exhaust cooling water, it is sufficiently heated by the exhaust cooling water.

  Therefore, according to the present embodiment, the configuration of one total heat exchanger 117 on the anode side and the cathode side can be simplified without causing a decrease in heating efficiency due to the exhaust cooling water with respect to the reaction gas. .

  Here, in FIG. 1, the flow directions of the gases and the cooling fluid in the fuel cell 101 and the total heat exchangers 117 and 118 are merely schematically shown, and the flows of the gases and the cooling fluid between each other. It does not indicate a directional relationship (for example, so-called parallel flow or counter flow).

  The fuel cell power generation system 100 includes an inlet temperature sensor TS1, an outlet temperature sensor TS2, and a control device 108. Here, the inlet temperature sensor TS1 and the outlet temperature sensor TS2 are each constituted by a thermistor, and the temperature of the cooling water at the inlet 401 and the outlet 402 of the fuel cell 101 (more precisely, cell stack 1 described later) in the cooling water circulation passage 112 is measured. Each is detected, and the detected value is input to the control device 108. The control device 108 is configured by an arithmetic device such as a microcomputer, and controls required components of the fuel cell power generation system 100 to control the operation of the fuel cell power generation device 100. Here, in this specification, a control device means not only a single control device but also a control device group in which a plurality of control devices cooperate to execute control. Therefore, the control device 108 does not necessarily need to be configured as a single control device, and a plurality of control devices are arranged in a distributed manner, and they are configured to control the operation of the fuel cell power generation device 101 in cooperation with each other. It may be.

  Specifically, the control device 108 controls at least the fuel gas supply device 102, the oxidant gas supply device 103, the heat dissipation device 105, and the cooling water circulation pump 109, and in particular, detects the inlet temperature sensor TS1 and the outlet temperature sensor TS2. Based on the value, at least one of the heat dissipation device 105 and the cooling water circulation pump 109 is controlled to adjust the temperature of the cooling water to a predetermined temperature, and the fuel gas supply device 102 and the oxidant gas supply device 103 are controlled. The fuel gas and oxidant gas supply rate (flow rate) and pressure loss are adjusted.

  Next, the structure of the fuel cell 101 will be described in detail.

  2 is a perspective view showing a schematic configuration of the fuel cell of FIG. 1, and FIG. 3 is a cross-sectional view taken along the plane III-III of FIG.

  In FIG. 2, the vertical direction in the fuel cell is represented as the vertical direction in the figure. This also applies to FIGS. 4 to 7 described later.

  As shown in FIG. 2, the fuel cell 101 has a cell stack 1. The cell stack 1 includes a cell laminate 201 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 201. And a fastener (not shown) that fastens the cell laminate 201 and the first and second end plates 3 </ b> A, 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 above one side portion (hereinafter referred to as a first side portion) of the cell stack 201 so as to penetrate the cell stack 201 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 the oxidant gas supply path 107 of FIG. 1 is configured at the outer opening (oxidant gas inlet 404) of the through hole. An oxidant gas supply pipe 51 is connected. The other end of the oxidant gas supply manifold 4 is closed by a second end plate 3B. Further, an oxidant gas discharge manifold 7 is formed below the other side portion (hereinafter referred to as a second side portion) of the cell stack 201 so as to penetrate the cell stack 201 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 the oxidant gas discharge path 111 of FIG. 1 is configured at the outer opening (oxidant gas outlet) of the through hole. An oxidant gas discharge pipe 52 is connected.

  A fuel gas supply manifold 5 is formed above the second side portion of the cell stack 201 so as to penetrate the cell stack 201 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 the fuel gas constituting the fuel gas supply path 109 in FIG. A supply pipe 53 is connected. 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 201 so as to penetrate the cell stack 201 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 the fuel gas constituting the fuel gas discharge passage 110 in FIG. 1 is formed at the outer opening (fuel gas outlet) of the through hole. A discharge pipe 54 is connected.

  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 201 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 an outside opening (cooling water inlet 401) of the through hole is connected to the cooling water supply pipe 30. The cooling water supply pipe 30 constitutes a portion of the cooling water circulation passage 112 in FIG. 1 between the discharge port (not shown) of the circulation pump 106 and the fuel cell 101. 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 201 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 an outer opening (cooling water outlet 402) of the through hole. The cooling water supply pipe 31 constitutes a portion of the cooling water circulation passage 112 in FIG. 1 between the suction port of the circulation pump 106 and the fuel cell 101.

  As shown in FIG. 3, 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 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. 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, as will be described later. The manifold hole and the cooling water outlet manifold hole are connected to 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 passage 19 is formed so as to connect the fuel gas inlet manifold hole and the fuel gas outlet manifold hole, and the cooling water passage 29 is connected to the cooling water inlet manifold hole, as will be described later. A cooling water outlet manifold hole is formed to be connected. 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. Moreover, although each flow path 17, 19, 28, 29 is comprised by two flow paths in FIG. 3, respectively, you may be comprised by many 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.

  The polymer electrolyte membrane 41 is made of a material capable of selectively transporting hydrogen ions, and here is made of a perfluorocarbon sulfonic acid material. The cathode 42A and the anode 42B are composed of a catalyst layer (not shown) formed on the principal surfaces opposite to each other of the polymer electrolyte 41 and a gas diffusion layer (not shown) formed on the catalyst layer. Has been. The catalyst layer is mainly composed of carbon powder carrying a platinum-based metal catalyst. The gas diffusion layer is made of non-woven fabric, paper or the like having air permeability and conductivity.

  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.

  4 is a front view of the cathode side separator, FIG. 5 is a rear view thereof, FIG. 6 is a front view of the anode side separator, and FIG. 7 is a rear view thereof.

  As shown in FIG. 4, 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 a cooling water inlet manifold hole 15 and an outlet manifold. It has a hole 16. The separator 10 further has a gas flow path 17 that connects the manifold holes 11 and 13 on the surface facing the cathode, and a flow path 19 that connects the manifold holes 15 and 16 of the cooling water on the back surface. .

  In FIG. 4, the inlet manifold hole 11 for the oxidant gas is provided on the upper side of one side of the separator 10 (the left side of the drawing: hereinafter referred to as the first side), and the outlet manifold hole 13 is formed on 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 inlet manifold hole 11 and outlet manifold hole 13 for the oxidant gas, and the inlet manifold hole 12 and outlet manifold hole 14 for the fuel gas are formed in a long hole shape that is long in the vertical direction. 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 (channel grooves). 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. 5, 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.

  As shown in FIG. 6, the anode separator 20 includes an oxidant gas inlet manifold hole 21 and an outlet manifold hole 23, a fuel gas inlet manifold hole 22 and an outlet manifold hole 24, and a cooling water inlet manifold hole 25 and an outlet manifold. It has a hole 26. The separator 20 further has a gas flow path 28 that connects the manifold holes 22 and 24 on the surface facing the anode, and a flow path 29 that connects the manifold holes 25 and 26 of the cooling water on the back surface. .

  In FIG. 6, the oxidant gas inlet manifold hole 21 is provided on the upper side of one side of the separator 20 (the right side of the drawing: hereinafter referred to as the first side), and the outlet manifold hole 23 is formed on the separator 20. 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 inlet manifold hole 21 and the outlet manifold hole 23 for the oxidant gas, and the inlet manifold hole 22 and the outlet manifold hole 24 for the fuel gas are formed in a long hole shape that is long in the vertical direction. 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. 7, the cooling water channel 29 is formed so that the left and right in the drawing are opposite to the cooling water channel 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 fuel 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 in the vertical direction as a whole. 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.

  In the fuel cell 101 configured as described above, fuel gas, oxidant gas, and cooling water flow as follows.

  1 to 7, 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 time, the fuel gas consumed by reacting with the oxidant gas via the anode 42B, the polymer electrolyte membrane 41, and the cathode 42A flows out from the outlet manifold hole 24 to the fuel gas discharge manifold 6. The gas 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 received from them, 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. Through 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.

  Next, configuration examples of the anode side total heat exchanger 117 and the cathode side total heat exchanger 118 will be described.

  8 is a perspective view showing a configuration of a total heat exchange cell stack constituting the anode-side total heat exchanger 117 of FIG. 1, and FIG. 9 is a cross-sectional view taken along the plane IX-IX of FIG.

  As shown in FIGS. 2, 3, 8, and 9, the anode-side total heat exchanger 117 is mainly composed of a total heat exchange cell stack 301 having the same configuration as the cell stack 1 of the fuel cell 101. The structure will be described with reference to the cell stack 1.

  The total heat exchange cell stack 301 includes a cell stack 302 in which cells 202 having a plate-like overall shape are stacked in the thickness direction, and first and second end plates disposed at both ends of the cell stack 302. 203A and 203B, and a fastener (not shown) that fastens the cell stack 302 and the first and second end plates 203A and 203B in the stacking direction of the cells 202.

The cell stack 302 includes an oxidant gas supply manifold 4, an oxidant gas discharge manifold 5, a fuel gas supply manifold 7, and a fuel gas discharge manifold 6 of the cell stack 1.
Are formed, a first fluid supply manifold 204, a first fluid discharge manifold 207, a second fluid supply manifold 205, and a second fluid discharge manifold 206 are formed. The first fluid supply manifold 204 and the second fluid supply manifold 205 are connected to the first fluid supply pipe 251 and the second fluid supply pipe 253, respectively, through through holes provided in the end plate 203A. ing. Further, the first fluid discharge manifold 207 and the second fluid discharge manifold 206 are respectively connected to the first fluid discharge pipe 252 and the second fluid discharge pipe 254 via through holes provided in the end plate 203B. It is connected. Unlike the cell stack 1, the cell stack 302 is not provided with a cooling water supply manifold and a cooling water discharge manifold.

  The total heat exchange cell 202 includes a pseudo MEA 243 and a first separator 210 and a second separator 220 that sandwich the pseudo MEA 243. The pseudo MEA 243 is configured in the same manner as the MEA 43 of the cell stack 201 except that the anode 42B and the cathode 42A are omitted from the MEA 43 of the cell stack 201. Therefore, the pseudo MEA 243 has a solid polymer film like the MEA 43 of the cell stack 201. However, in the pseudo MEA 243, the solid polymer membrane functions as a total heat exchange membrane.

The first and second separators 210 and 220 are configured in the same manner as the cathode-side separator 10 and the anode-side separator 20 of the cell stack 201 except that the cooling water flow path is not formed on the back surface (outer surface). Accordingly, the first fluid inlet manifold holes 211 and 221, the first fluid outlet manifold holes (not shown), and the second fluid are formed in the peripheral portions of the first separator 210 and the second separator 220, respectively. Inlet manifold holes 212, 222 and a second fluid outlet manifold hole (not shown). The first fluid inlet manifold holes 211 and 221 and the second fluid inlet manifold holes 212 and 222 are formed on opposite sides of the upper portions of the first separator 210 and the second separator 220, respectively. Yes. In addition, the first fluid outlet manifold hole and the second fluid outlet manifold hole are arranged on the opposite sides of the lower portions of the first separator 210 and the second separator 220, respectively. The manifold holes are located below the second fluid inlet manifold holes 212, 222 and the second fluid outlet manifold holes are located below the first fluid inlet manifold holes 211, 221 respectively. Is formed. A first fluid channel (hereinafter referred to as a first fluid channel) 217 is provided on the front surface (inner surface) of the first separator 210 in the same manner as the cathode-side separator 10. Hole 211
And a first fluid outlet manifold hole. On the front surface (inner surface) of the second separator 220, similarly to the anode-side separator 20, a second fluid channel (hereinafter referred to as a second fluid channel) 228 has a second fluid inlet manifold hole 221. And the outlet manifold hole of the second fluid. In addition, the first fluid inlet manifold holes 211 and 221, the first fluid outlet manifold holes (not shown), and the second separators 220 and 220 of the first separator 210 and the second separator 220 are formed in the peripheral portion of the pseudo MEA 243. The first fluid inlet manifold holes (not shown), the first fluid outlet manifold holes 212, 222, and the second fluid outlet manifold holes (not shown), respectively. A manifold hole (not shown), a second fluid inlet manifold hole (not shown), and a second fluid outlet manifold hole (not shown) are formed.

  The pseudo MEA 243, the first separator 210, and the second separator 220 in all the total heat exchange cells 202 have a first fluid inlet manifold hole, a first fluid outlet manifold hole, and a second fluid outlet. The inlet manifold hole and the second fluid outlet manifold hole are connected to each other, so that the first fluid supply manifold 204, the first fluid discharge manifold 207, the second fluid supply manifold 205, and the second fluid discharge manifold 206 are connected. , Each is formed. Note that the first separator 210 and the second separator 220 may be configured by one separator.

  The anode-side total heat exchanger 117 includes a first total heat exchange cell stack 301A configured by the total heat exchange cell stack 301 and an anode-side cooling water heat exchange configured by a general heat exchanger. 303A.

  In the first total heat exchange cell stack 301 </ b> A, the first fluid supply manifold 204, the first fluid flow path 217, and the first fluid discharge manifold 207 are provided on the supply-side fuel gas flow path of the anode-side total heat exchanger 117. The second fluid supply manifold 206, the second fluid flow path 228, and the second fluid discharge manifold 205 constitute the upstream side portion of the 117a, and the discharge-side fuel gas flow path 117b of the anode-side total heat exchanger 117. It is composed. The first fluid supply pipe 251 constitutes a portion 109a of the fuel gas supply passage 109 on the fuel gas supply device 102 side, and the first fluid discharge pipe 252 is a second total heat exchange cell described below. Connected to the inlet of the first fluid supply manifold 204 of the stack 301B. The second fluid supply pipe 254 constitutes the fuel cell 101 side portion 110a of the fuel gas discharge passage 110, and the second fluid discharge pipe 253 constitutes the atmosphere side portion 110b of the fuel gas discharge passage 110. is doing.

  Further, in the anode side cooling water heat exchanger 303A, heat exchange is possible between the cooling water and the fuel gas by a known configuration.

  In the anode-side total heat exchanger 117 configured as described above, in the first total heat exchange cell stack 301A, the fuel gas supplied to the fuel cell 101 to the first fluid manifold 204 (hereinafter referred to as supply fuel gas). , And the fuel gas discharged from the fuel cell 101 (hereinafter referred to as exhausted fuel gas) is supplied to the second fluid manifold 206. In each total heat exchange cell 202, the supply fuel gas flowing through the first fluid flow path 217 and the exhaust fuel gas flowing through the second fluid flow path 228 are totally exchanged (heated) via the polymer electrolyte membrane 41. The supply fuel gas is humidified and heated by the exhaust fuel gas. Then, in the anode side cooling water heat exchanger 303A, the supplied fuel gas and the exhaust cooling water flowing through the inside do not exchange moisture, but only exchange heat, whereby the first total heat exchange stack 301A The supplied fuel gas that has undergone total heat exchange passes through the fuel cell 101 and is further heated by the discharged cooling water that has been heated. The supplied fuel gas thus humidified and heated is supplied to the fuel cell 101.

  Next, the configuration of the cathode side total heat exchanger 118 will be described. The cathode-side total heat exchanger 118 has a configuration in which the anode-side cooling water heat exchanger 303A of the anode-side total heat exchanger 117 is replaced with a fourth total heat-exchange cell stack 301D configured by the total heat-exchange cell stack 301. Have. That is, the cathode-side total heat exchanger 118 includes a third total heat exchange cell stack 301C and a fourth total heat exchange cell stack 301D configured by the total heat exchange cell stack 301 shown in FIGS. have. In the third total heat exchange cell stack 301C, the first fluid supply pipe 251 constitutes the portion 107a on the oxidant gas supply device 103 side of the oxidant gas supply channel 107, and the first fluid supply The manifold 204, the first fluid flow path 217, and the first fluid discharge manifold 207 constitute the upstream side of the supply-side oxidant gas flow path 118a of the cathode-side total heat exchanger 118, and the first fluid discharge pipe 252. Is connected to the inlet of the first fluid supply manifold 204 of the fourth total heat exchange cell stack 301D. The second fluid supply pipe 254 constitutes a portion 111a on the fuel cell 101 side of the oxidant gas discharge channel 111, and includes a second fluid supply manifold 206, a second fluid channel 228, and a second fluid. The discharge manifold 205 forms the discharge-side oxidant gas flow path 118b of the cathode-side total heat exchanger 118, and the second fluid discharge pipe 254 forms the atmosphere-side portion 111b of the oxidant gas discharge flow path 111. .

  Further, in the fourth total heat exchange cell stack 301D, the first fluid supply manifold 204, the first fluid flow path 217, and the first fluid discharge manifold 207 are provided on the supply side oxidation of the cathode side total heat exchanger 118. The second fluid supply manifold 206, the second fluid passage 228, and the second fluid discharge manifold 205 constitute the downstream portion of the agent gas passage 118a, and the cooling water passage 118c of the cathode-side total heat exchanger 118. Is configured. Further, the first fluid supply pipe 251 constitutes the first fluid discharge pipe 252 of the third total heat exchange cell stack 301C, and the first fluid discharge pipe 252 is the fuel of the oxidant gas supply passage 107. A portion 107b on the battery 101 side is formed. Further, the second fluid supply pipe 254 constitutes the fuel cell 101 side portion of the branch path 112 b of the cooling water circulation path 112, and the second fluid discharge pipe 253 is a heat dissipation device for the branch path 112 a of the cooling water circulation path 112. This constitutes the part on the 105 side.

  In the cathode-side total heat exchanger 118 configured as described above, in the first total heat exchange cell stack 301C, an oxidant gas (hereinafter referred to as supply oxidant gas) supplied to the fuel cell 101 to the first fluid manifold 204. And the oxidant gas discharged from the fuel cell 101 (hereinafter referred to as “discharged oxidant gas”) is supplied to the second fluid manifold 206. In each total heat exchange cell 202, the supply oxidant gas flowing through the first fluid flow path 217 and the exhaust oxidant gas flowing through the second fluid flow path 228 are exchanged through the polymer electrolyte membrane 41. So that the supplied oxidant gas is humidified and heated by the exhaust oxidant gas. Then, in the fourth total heat exchange cell stack 301D, the supply oxidant gas that has undergone total heat exchange in the third total heat exchange stack is supplied to the first fluid manifold 204, and the fuel cell is supplied to the second fluid manifold 206. The discharged cooling water discharged from 101 is supplied. In each total heat exchange cell 202, the supply oxidant gas flowing through the first fluid flow path 217 and the exhaust cooling water flowing through the second fluid flow path 228 exchange total heat via the polymer electrolyte membrane 41. As a result, the supplied oxidant gas that has undergone total heat exchange in the third total heat exchange stack is further humidified and heated by the exhaust cooling water that has been heated through the fuel cell 101. The supplied oxidant gas thus humidified and heated is supplied to the fuel cell 101.

  In the following description, the supply fuel gas and the supply oxidant gas may be collectively referred to as supply reaction gas, and the exhaust fuel gas and the discharge oxidant gas may be collectively referred to as discharge reaction gas.

  1 to 3, the reaction gas is supplied to the fuel cell 101 after being humidified so that the relative humidity becomes 100% relative to the temperature of the fuel cell 101 (more precisely, the dew point conversion temperature described below). . Here, in the present specification, the temperature obtained by converting the total water content of the reaction gas into the dew point is referred to as “dew point converted temperature”. This concept was introduced to define the total amount of water present with the reaction gas, including the state where the relative humidity of the reaction gas exceeds 100% and the moisture exists in the reaction gas in a mist state. It is to do. In this specification, a state in which liquid water (condensation water) can exist thermodynamically in the reaction gas is referred to as an “over-humidification” state, and the relative humidity of the reaction gas is 100%. A state where liquid water cannot exist thermodynamically is called a “full humidification” state. As described above, by humidifying the reaction gas, an area in the fuel cell 101 where an electrochemical reaction for power generation (hereinafter referred to as a power generation reaction) occurs is 100% relative humidity over the entire area. The atmosphere is humidified as described above (fully humidified or over-humidified). Thereby, chemical deterioration of the polymer electrolyte contained in the polymer electrolyte membrane 41 and the anode 42B and cathode 42A is prevented, and the durability of the fuel cell 101 is improved. In addition, a perfluorocarbon sulfonic acid-based material is used for the fuel electropolymer electrolyte membrane. Since this polymer electrolyte membrane exhibits ionic conductivity in a state containing moisture, the region where the power generation reaction inside the fuel cell 101 occurs is humidified so as to be fully humidified or excessively humidified over the entire region. An operation method for maintaining a stable atmosphere is realized by a method that does not reduce the efficiency of the fuel cell power generation system 100.

  Accordingly, the present inventors basically have a configuration shown in FIGS. 1 to 7 and manufacture and operate a fuel cell using a separator specially processed for temperature measurement, and a power generation reaction actually occurs. The temperature distribution in the area was measured. However, the fuel gas and the oxidant gas were humidified using a bubbler instead of a total heat exchanger. Here, the “region where the power generation reaction occurs” (hereinafter sometimes referred to as “power generation region”) refers to the anode 42b and the cathode 42A.

  FIG. 10 is a schematic diagram showing the structure of the separator used for measuring the temperature distribution of the cell stack. In FIG. 10, the cathode side separator 10 and the anode side separator 20 are illustrated in a perspective manner as viewed from the thickness direction of the cell. Further, the flow paths 17, 19, 28, and 29 of the separators 10 and 20 are shown so that a plurality of flow paths are represented by a single line.

  As shown in FIG. 10, pores 200 are formed in the cathode side separator 10 and the anode side separator 20 in parallel to the main surface. The pores 200 are formed so as to extend from the end faces of the separators 10 and 20 toward the center thereof, or from one end face to the opposite end face so as to penetrate the separators 10 and 20 obliquely through the center. ing. By inserting a thermocouple into the pore 200 at an appropriate depth, the temperatures at the five positions A to D of the separators 10 and 20 were measured. The measurement position C is the center of the separators 10 and 20 in plan view. The measurement positions A, B, D, and E are positions close to the oxidant gas inlet manifold hole 11 in a region overlapping the cathode 42A and the anode 42B of each separator 10 and 20 in plan view, and the fuel gas inlet manifold. The position near the hole 12, the position near the oxidant gas outlet manifold hole 13, and the position near the fuel gas outlet manifold hole 14. Further, the measurement positions A to E are located in this order from the upstream side to the downstream side along the cooling water flow paths 19 and 29 in the plan view of the separators 10 and 20.

  As a result of the temperature distribution measurement, the present inventors have found the following facts.

  FIG. 11 is a graph showing a measurement example of the temperature distribution of the cell stack when cooling is performed for each cell. In FIG. 11, the horizontal axis indicates the cell number, and the vertical axis indicates the temperature of the cell stack. Also, the black circles indicate the temperature at the measurement position A of the separators 10 and 20 shown in FIG. 10, the black diamonds indicate the temperature at the measurement position B of the separators 10 and 20 shown in FIG. 10 is the temperature at the measurement position C of the separators 10 and 20 shown in FIG. 10, the black triangle mark is the temperature at the measurement position D of the separators 10 and 20 shown in FIG. 10, and the white diamond mark is the plot. The temperature in the measurement position E of the separators 10 and 20 shown in FIG. The cell numbers are given in order from the cell 2 close to the cooling water entrance (outside opening of the through hole of the end plate 3A in FIG. 2) 401 to the cell stack 1. In the measurement example of FIG. 11 (experiment number 1 of FIG. 21 described later), the number of cells in the cell stack 1 is 40.

  Referring to FIG. 11, in the cell 2, the temperature is distributed so as to increase along the cooling water flow paths 19 and 29 and toward the downstream side. This is natural. On the other hand, in this temperature measurement, since the cooling water is supplied to the cell stack 1 by controlling the temperature so as to be 60 ° C. at the cooling water inlet 401 to the cell stack 1, the cooling water is supplied from the inlet 401. Region (anode 42B and cathode 42A) where the power generation reaction of the cell 2 (cell number 1) that flows into the cell stack 1 and is closest to the inlet 401 occurs (precisely, the regions facing each other across the separators 10 and 20 in the region) The temperature has already risen by about 1 ° C. before reaching (). In addition, between the cells 2, the temperature of the cell 2 increases as the cell number increases. That is, the temperature of the cell 2 increases as the distance from the cooling water inlet 401 to the cell stack 1 increases. The temperature difference between the cell 2 (cell number 1) closest to the cooling water inlet 401 to the cell stack 1 and the cell 2 (cell number 39) furthest away (hereinafter referred to as the temperature difference between both ends of the cell stack) is about It was 1 ° C. These phenomena are unexpected phenomena for the present inventors and are new findings.

  Referring to FIGS. 2, 3, and 10, after the cooling water is supplied to the cell stack 1, first, the cooling water supply manifold 8 is provided for each predetermined number of cells (here, one cell). After being distributed to the cooling water flow paths 19 and 29 and flowing through the cooling water flow paths 19 and 29, they gather in the cooling water discharge manifold 9 and are discharged from the cooling water discharge manifold 9 to the outside of the cell stack 1. In this process, the cooling water entering the cell stack 1 once flows into the cooling water supply manifold 8 and exchanges heat with the fuel cell 101 (cell stack 1) while flowing through the cooling water supply manifold 8. When the cooling water reaches 2, the temperature is considered to be higher than the temperature at the inlet 401 to the stack 1. In addition, the cooling water supply manifold 8 also has an upstream side and a downstream side of the cooling water in the stacking direction of the cell stack 1, and the cell passes while the cooling water flows from the upstream side to the downstream side in the cooling water supply manifold 8. As a result, heat exchange with the stack 1 is performed, and as a result, the portion near the downstream end of the cooling water supply manifold 8 in the cell stack 1 is hotter than the portion near the upstream end of the cooling water supply manifold 8 in the cell stack 1. It is considered that. In FIG. 11, the temperature at both ends of the cell stack 1 is lower than the other portions because of the heat radiation of the end plates. The same applies to FIG. 12 described later.

  When the temperature at the inlet to the cooling water cell stack 1 (hereinafter referred to as the cooling water inlet temperature) and the dew point conversion temperature of the reaction gas supplied to the cell stack 1 are the same, the above phenomenon is In the region where this occurs, the temperature of the cell stack 1 is about 1 ° C. or more higher than the cooling water inlet temperature, which means that the reaction gas is in a dry state at about 1 ° C. in terms of the dew point. Therefore, in practice, unless the reaction gas is supplied with the dew point conversion temperature of the reaction gas at least 1 ° C. higher than the cooling water inlet temperature, the entire region where the power generation reaction occurs in the cell stack 1 is fully humidified or excessively heated. The humid atmosphere cannot be maintained. In consideration of the temperature difference between the cells 2, it is more preferable to supply the reaction gas with the dew point conversion temperature of the reaction gas being at least 2 ° C. higher than the cooling water inlet temperature. The entire region where the reaction takes place cannot be kept in a full or over-humidified atmosphere. However, since the temperature difference between both ends of the cell stack varies depending on the number N of cells of the cell stack 1, the dew point converted temperature at the inlet of the reaction gas to the cell stack 1 (hereinafter referred to as the inlet dew point converted temperature) is taken into consideration. T1) is preferably higher by (1 ° C. + 0.02 ° C. × (N−1)) or more than the cooling water inlet temperature (hereinafter referred to as T2). This will be described in detail later.

  By the way, since fuel gas is consumed by the power generation reaction at the anode, the ratio of the moisture content to the total amount of the fuel gas (hereinafter referred to as the moisture content ratio of the fuel gas) is lower in the upstream of the fuel gas flow path 28 and the fuel is more downstream. The moisture content of the gas increases. That is, the dew point converted temperature of the fuel gas increases from the upstream side toward the downstream side in the fuel gas channel 28. On the other hand, since water is also generated by the power generation reaction at the cathode, the ratio of the moisture amount to the total amount of the oxidant gas (hereinafter referred to as the moisture content ratio of the oxidant gas) is lower in the upstream of the oxidant gas flow path 17 and downstream. The moisture content of the oxidant gas increases. That is, the dew point conversion temperature of the oxidant gas increases from the upstream toward the downstream in the oxidant gas flow path 18. On the other hand, as the cooling water flows from the cooling water inlet toward the cooling water outlet, the amount of heat exchange with the cell stack 1 increases. Therefore, in each cell 2, the temperature increases from the cooling water inlet to the cooling water outlet. A temperature distribution is formed.

  Therefore, in each cell 2 (precisely, each separator 10, 20), the reaction with the lowest water content ratio (hereinafter referred to as the water content ratio of the reaction gas) with respect to the total amount of the reaction gas (fuel gas and oxidant gas). The most upstream part of the gas flow paths 17 and 28 and the most upstream part of the cooling water flow paths 19 and 29 having the lowest cooling water temperature are positioned at substantially the same position when viewed from the thickness direction, and the reaction gas water content ratio By positioning the most downstream part of the reaction gas channels 17 and 28 having the highest temperature and the most downstream part of the cooling water channels 19 and 29 having the highest temperature of the cooling water at substantially the same position as viewed from the thickness direction, the cell 2, the most upstream part and the most downstream part in the cooling water flow paths 19 and 29 are respectively the parts having the lowest dew point conversion temperature and the highest dew point conversion temperature in the reaction gas flow paths 17 and 28. BecomeAs a result, in each cell 2, a temperature gradient is formed so that the temperature generally increases from the most upstream end of the cooling water flow paths 19 and 29 toward the most downstream end of the cooling water flow paths 19 and 29 when viewed from the thickness direction. On the other hand, the reaction gas macroscopically (as a whole) flows from the most upstream portion of the cooling water flow paths 19 and 29 toward the most downstream portion. Therefore, in the reaction gas channels 17 and 28, the reaction gas dew-point conversion temperature is distributed so as to increase with the temperature from the most upstream to the most downstream, whereby the relative humidity of the reaction gas is increased. 17 and 28 are kept substantially constant. Therefore, at the inlet (inlet manifold holes 11 and 12) to the cell 2 (more precisely, each separator 10 and 20), the reaction gas is fully humidified or over-humidified (dew point conversion temperature is higher than the temperature of the cell stack 1. If it is high, the condition of full humidification or over humidification is satisfied over the entire length of the flow paths 17 and 28, and all the regions where the power generation reaction of the cell stack 1 occurs are fully humidified or over humidified. It becomes possible to keep it. The above-mentioned “the most upstream part of the reaction gas channels 17 and 28 and the most upstream part of the cooling water channels 19 and 29 are positioned at substantially the same position when viewed from the thickness direction of the cell 2, and the reaction gas channel The configuration in which the most downstream portions of 17 and 28 and the most downstream portions of the cooling water channels 19 and 29 are positioned at substantially the same position when viewed from the thickness direction of the cell 2 is referred to as “reactive gas temperature rising gradient arrangement” in the present invention. .

  Further, when the supplied fuel gas and the supplied oxidant gas are humidified and heated using the exhaust heat of the fuel cell 101 as in the present embodiment, the dew point converted temperature of the supplied fuel gas and the supplied oxidant gas is the cooling water. In principle, it is impossible to humidify and heat the cell stack 1 so that it is higher than the temperature of the outlet 402 (outside opening of the through hole of the end plate 3B in FIG. 2) 402 (hereinafter referred to as cooling water outlet temperature). However, if configured as described above, the dew point converted temperature of the reaction gas to be supplied to the fuel cell 101 may be lower than the cooling water outlet temperature, and therefore, the supplied fuel gas and the supply gas using the exhaust heat of the fuel cell 101 may be used. In principle, it is possible to humidify and heat the oxidant gas.

  However, the amount of water produced by the reaction is determined by the current density, and the flow rates of the dry gas-based fuel gas and the oxidant gas at the outlet of the cell stack 1 are the fuel gas utilization rate (Uf) and the oxidant gas utilization rate (Uo). Therefore, if (cooling water outlet temperature T3) − (cooling water inlet temperature T2) = ΔT, depending on the current density, the fuel gas utilization rate, and the oxidant gas utilization rate, the electrode ( It is calculated whether full humidification or overhumidification can be realized over the entire area of the anode 42B and cathode 42A) surfaces (that is, all areas where power generation reaction occurs). Actually, between the anode 42B and the cathode 42A, accompanying the movement of protons due to the reaction, water moves from the anode 42B side to the cathode 42A side, and the generated water is referred to as reverse diffusion, from the cathode 42A side. Since the phenomenon of moving toward the anode 42B occurs at the same time, the dew point conversion temperature of the total water content of the anode 42B and the cathode 42A calculated from the current density, the fuel gas utilization rate, and the oxidant gas utilization rate is slightly different from the calculated value. To do.

Therefore, the cooling water inlet temperature is set to 60 ° C., and the temperature rise due to heat exchange in the fuel gas supply manifold 5 and the oxidant gas supply manifold 4 is anticipated. What is the dew point conversion temperature at the outlet of the cell stack 1 for fuel gas and oxidant gas (hereinafter referred to as outlet dew point conversion temperature) when supplied at 64 ° C. and a gas temperature of 64 ° C. (relative humidity 100%)? Was measured. As a result, when the steam reformed gas is a fuel gas, the current density is 0.2 A / cm ² , the fuel gas utilization rate Uf is 75%, and the oxidant gas utilization rate Uo is 50%, the fuel gas And the outlet dew point conversion temperature of the oxidant gas is 75.8 ° C. and the outlet dew point conversion temperature of the oxidant gas is 73.6 ° C. The outlet dew point converted temperature of the fuel gas was 79 ° C., and the outlet dew point converted temperature of the oxidant gas was 72.5 ° C. Accordingly, it has been found that unless ΔT is set to 12.5 ° C. or lower, full humidification or over humidification cannot be achieved over the entire surface of the electrode.

In the fuel cell 101 described above, when the current density is 0.07 A / cm ² , the fuel gas utilization rate Uf is 70%, and the oxidant gas utilization rate Uo is 45%, the fuel gas and the oxidation The outlet dew point conversion temperature of the total water content of the agent gas is calculated to be 75.4 ° C. for the fuel gas and 73.1 ° C. for the oxidant gas. The gas reached 71 ° C. Therefore, in this case, unless ΔT is set to 11 ° C. or less, the electrode surface cannot be fully humidified or overhumidified over the entire surface. The trend is that as the current density increases, the fuel gas outlet dew point calculation temperature and the oxidant gas outlet dew point calculation temperature become equal, and the fuel gas outlet dew point conversion temperature and the oxidant gas outlet dew point conversion temperature Is larger, ΔT cannot be increased because the cooling water outlet temperature needs to be suppressed to a temperature equal to or lower than the lower outlet dew point conversion temperature. For this reason, it has been found that it is ideal that the outlet dew point converted temperature of the total moisture content of the fuel gas is equal to the outlet dew point converted temperature of the total moisture content of the oxidant gas.

In the fuel cell 101 described above, the cooling water inlet temperature is set to 66 ° C., both the fuel gas and the oxidant gas are supplied at a dew point conversion temperature of 70 ° C. (relative humidity 100%), and the steam reformed gas is used as fuel. When the current density is 0.7 A / cm ² , the fuel utilization rate Uf is 75%, and the oxidant gas utilization rate Uo is 50%, the calculated total water content of the fuel gas and the oxidant gas The outlet dew point conversion temperature was about 79 ° C. when both were equal. Therefore, it has been found that even in this case, unless the ΔT is set to 13 ° C. or less, the entire electrode surface cannot be fully humidified or overhumidified. At this time, the outlet dew point conversion temperature can be increased by increasing the oxidant gas utilization rate Uo. Under the same conditions as described above, when the oxidant gas utilization rate Uo is 60%, the outlet Even when the dew point conversion temperature is about 80 ° C. and the oxidant gas utilization rate Uo is 70%, the outlet dew point conversion temperature is about 81 ° C. Even in this case, it has been found that ΔT needs to be 15 ° C. or less. .

  In the fuel cell power generation system 100, when the reaction gas is humidified and heated and supplied in the fuel cell power generation system 100 as in the present embodiment, the reaction gas is supplied to a dew point conversion temperature higher than the cooling water outlet temperature. Since it is impossible in principle to humidify and heat, ΔT should be made as large as possible in order to supply a reaction gas having a dew point conversion temperature that is 2 ° C. higher than the cooling water inlet temperature based on the above knowledge. This is advantageous from the viewpoint of humidification of the reaction gas and easiness of heating. However, as described above, there is a limit on ΔT in order to achieve full humidification or excessive humidification over the entire surface of the electrode, and the temperature fluctuation range of temperature control in the actual fuel cell power generation system 100 (for example, plus or minus) (2 ° C.) and the like, it has been found that in any case, in order to make the electrode surface full humidified or excessively humidified, it is practically desirable to suppress ΔT to about 10 ° C. or less.

  Further, in the fuel cell power generation system 100, when the reaction gas supplied to the fuel cell 101 is humidified and heated by effectively using the exhaust heat of the fuel cell 101, the reaction gas flow path is set to the “reaction gas temperature rise” described above. It was found that T2 ≦ T1 ≦ T3 when the cooling water outlet temperature is T3 by satisfying certain conditions (reactive gas temperature before humidification and heating, heat exchange efficiency, etc.). .

  Here, assuming that the dew point converted temperature at the outlet of the reaction gas from the cell stack 1 (hereinafter referred to as outlet dew point converted temperature) is T4, the temperature of the reactive gas at the outlet of the cell stack 1 is substantially equal to the cooling water outlet temperature T3. Therefore, moisture corresponding to T4-T3 is discharged as condensed water. Therefore, when the supplied reaction gas is humidified and heated only by total heat exchange between the supplied reaction gas and the exhaust reaction gas, in order to efficiently humidify and heat the supplied reaction gas, the condensed water is evaporated and humidified. Extra heat corresponding to the latent heat for use in the process is required. In this case, the present inventors have conceived that the total heat exchange can be performed more efficiently if the heat retained by the cooling water (discharge cooling water) discharged from the cell stack 1 is used as a heat source corresponding to the latent heat. .

  On the other hand, when the supply reaction gas is humidified and heated only by total heat exchange between the supply reaction gas and the discharge reaction gas without using the heat retained in the discharge cooling water in this way (in Embodiment 4 described later). Efficiently, if the total heat exchanger is increased, the efficiency increases. However, in the case of a total heat exchanger in a practical range, the heat exchangeable coolant water outlet temperature T3 and the reaction gas inlet dew point conversion temperature T1 It has been found that the temperature difference (hereinafter referred to as heat exchangeable temperature difference) is almost limited to about T3−T1 ≧ 4 ° C.

  In addition, when the cooling fluid is water, it is possible to directly exchange the total amount of heat between the supplied reaction gas and the discharged cooling water (corresponding to Embodiment 3 described later). T3-T1 ≧ 2 ° C. was found to be the limit.

  In addition, when the supply reaction gas and the exhaust reaction gas are subjected to total heat exchange and the heat retained in the exhaust cooling water is used as a heat source corresponding to the latent heat, the supply reaction gas is humidified and heated (in the second embodiment). It was also found that the limit of the heat exchangeable temperature difference is about T3−T1 ≧ 2 ° C.

  Further, if the supply reaction gas and the exhaust reaction gas are humidified and heated by total heat exchange, and further this total heat exchange is performed between the humidified and heated supply reaction gas and the exhaust cooling water (corresponding to this embodiment), It has been found that the limit value of the exchangeable temperature difference can be improved to about T3−T1 ≧ 1 ° C.

  Therefore, when the reaction gas supplied to the fuel cell 101 is humidified and heated by effectively using the exhaust heat of the fuel cell 101, T2 ≦ T1 ≦ T3, T3-T2 ≦ 10 ° C., T1-T2 ≧ 2. It has been found that it is preferable to satisfy all operating conditions of ° C. and T3-T1 ≧ 1 ° C.

  In addition, this finding is supplemented.

  When the reaction gas is humidified and heated using the exhaust heat of the fuel cell 101, it is necessary to select an optimum method depending on the fuel cell power generation system. For example, when it is desired to use heat as high as possible in a hot water supply system such as a cogeneration system, the method of humidifying and heating the supplied reaction gas by mere total heat exchange between the supplied reaction gas and the exhaust cooling water, Therefore, it is desirable to select a system in which the supply reaction gas and the exhaust reaction gas are subjected to total heat exchange and the supply reaction gas after the total heat exchange is further subjected to total heat exchange with the exhaust cooling water. In addition, when the cooling medium is other than water (for example, antifreeze), the exhaust cooling medium and the supplied reaction gas cannot be directly subjected to total heat exchange. Therefore, the supply reaction gas and the exhaust reaction gas are subjected to total heat exchange. It is desirable to select a system in which the reaction gas supplied after the total heat exchange is further simply exchanged with the exhaust cooling water.

  Furthermore, as a result of separate investigations, if the supplied fuel gas contains a certain amount of moisture in advance, as in the case where the supplied fuel gas is a steam reformed gas, basically the total heat with the exhausted fuel gas Although only replacement is sufficient, in some cases, it is higher by simply exchanging the supplied fuel gas after total heat exchange with the exhaust cooling water and effectively using only the heat of the exhaust cooling water as latent heat. It has been found that fuel gas having a dew point conversion temperature can be supplied.

  Next, knowledge from another viewpoint will be described.

  If a fully humidified or overhumidified atmosphere is maintained throughout the power generation reaction, flooding is more likely to occur. Therefore, by forming the flow path so that the reaction gas flows without going against gravity, the gravity can be effectively used to discharge generated water and condensed water, and as a result, flooding can be suppressed. It turned out to be possible.

  In addition, since the glass transition temperature of the polymer electrolyte membrane 41 is about 90 ° C., the cooling water outlet temperature T3 is desirably 90 ° C. or less in consideration of the durability and creep resistance of the polymer electrolyte membrane 41. Also, it was found from the durability test results that the cooling water outlet temperature T3 is more preferably 80 ° C. or lower.

When the fuel cell power generation system 100 is used as a home cogeneration system,
The higher the temperature of the heat source for heating the supplied reaction gas, the better. However, from the viewpoint of durability, particularly deterioration in durability of the polymer electrolyte membrane 41, it is desirable that the temperature be 0 ° C. or higher and as low as possible. In addition, when the cogeneration system is used as a hot water supply system, the hot water storage temperature is preferably 60 ° C. or higher from the viewpoint of preventing the growth of Legionella bacteria in the hot water storage tank. In addition, in order to obtain a hot water storage temperature of 60 ° C. by exchanging heat of hot water with cooling water, the cooling water needs to be about 63 ° C. Since the temperature is lowered by heat exchange, the cooling water outlet temperature T3 needs to be higher by about 3 ° C. From this, it is desirable that the cooling water outlet temperature T3 is 66 ° C. or higher.

  Furthermore, when steam reformed gas is used as the fuel gas, the dew point converted temperature T1 of the fuel gas is preferably 50 ° C. or higher from the viewpoint of the CO poisoning resistance of the anode catalyst.

  Although the above knowledge is about the case where it cools for every 1 cell, the inventors examined separately also about the case where it cools for every 2 cells.

FIG. 12 is a graph showing a measurement example of the temperature distribution of the cell stack when cooling is performed every two cells. In FIG. 12, the horizontal axis indicates the cell number, and the vertical axis indicates the temperature of the cell stack. The temperature measurement of the cell stack was performed in the same manner as in the case of cooling each cell described above. The results of this study, in the case of cooling in every two cells, the cell stack across a temperature difference is ^{2 ~0.3A} / cm ² about current density 0.1 A / cm is was about 2 ° C., 0.3 A the / cm ² or more current density, further temperature distribution becomes large, as shown in FIG. 12 at 0.5A / cm ^2, the temperature in the laminating direction of about 4 ° C., 1.0A / cm ² at about 6 ° C. A distribution was found to occur. Therefore, even when using a fuel cell 101 in the range of 0.1A / cm ² ~0.3A / cm ² about the current density, when every two cell cooling for the cooling fluid inlet temperature, about 4 ° C. It has been found that unless the supply gas having a higher dew point conversion temperature is supplied, the entire region where the power generation reaction occurs cannot be maintained in a fully humidified or overhumidified atmosphere. In addition, since the temperature difference between both ends of the cell stack varies depending on the number N of cells of the cell stack 1, considering this, the dew point converted temperature T1 of the reaction gas is set to (3 ° C. + 0.02 ° C. × (N -1)) It is preferable to make it higher. This will be described in detail below.
<Study on the preferable dew point conversion temperature T1 of the reaction gas>
First, consider the case of cooling for each cell.

  In the above description, when cooling is performed for each cell, the dew point converted temperature T1 is preferably equal to or higher than the cooling water inlet temperature T2 + (1 ° C. + 0.02 ° C. × (N−1)). Replenish data and consider in detail.

  FIG. 14 is a graph showing another measurement example of the temperature distribution of the cell stack when cooling is performed for each cell.

  The measurement example in FIG. 14 is the same as the measurement example in FIG. 11 except that the number of cells in the cell stack 1 is 66. In addition, although the temperature of the cell in the middle of the cell stack 1 is not shown, this is because the temperature of the cell shows the same tendency as the temperature of the cells at both ends of the cell stack 1, and thus the measurement is omitted. It is.

  Measurement conditions (experimental conditions) in these measurement examples are as follows.

  In these measurement examples, the cooling water inlet temperature T2 is 60 ° C., the cooling water outlet temperature T3 is 68 ° C., and the difference ΔT between the cooling water inlet temperature T2 and the cooling water outlet temperature T3 is 8 ° C.

  The fuel gas utilization rate Uf is 75%, and the oxidant gas utilization rate Uo is 40%.

  Further, the equivalent diameter of each flow path (flow path groove) of the oxidant gas flow path 17 is 0.99 mm, and the equivalent diameter of each flow path (flow path groove) of the fuel gas flow path 28 is 0.99 mm. .

  The flow rate of the fuel gas at the channel outlet is 4.4 m / s, and the flow rate of the oxidant gas at the channel outlet is 4.5 m / s.

  The pressure loss in the oxidant gas channel 17 is 4 kPa, and the pressure loss in the fuel gas channel 28 is 6 kPa.

  Next, a conditional expression to be satisfied by the dew point converted temperature T1 will be examined.

11 and 14, the temperature (unit: ° C.) T at the measurement position A and the measurement position B is based on the cooling water inlet temperature T2 (60 ° C. in these measurement examples).
It can be approximated by a straight line of T = X ° C. + Y ° C. × (N−1).

Further, the temperature difference between both ends of the cell stack is proportional to the difference ΔT between the cooling water outlet temperature T3 and the cooling water inlet temperature T2, and in these measurement examples, ΔT = 8 ° C.
It can be approximated by a straight line of T = X ° C. + Y ° C. × (N−1) × ΔT / 8 ° C.

Therefore, the conditional expression that the dew point conversion temperature T1 should satisfy is
T1 ≧ T2 + (X ° C. + Y ° C. × (N−1) × ΔT / 8 ° C.).

  This linear approximation formula can be obtained by statistically processing the measurement data. Examples of the statistical method include a regression method and a least square method. Here, processing was performed by the method of least squares.

  And the numerical value of the constant X and the coefficient Y in this conditional expression was calculated | required from the measurement example of FIG.11 and FIG.14.

  FIG. 21 is a table showing the numerical values of the constant X and the coefficient Y of the conditional expression to be satisfied by the dew point converted temperature T1 when cooling is performed for each cell together with the current density.

  In FIG. 21, “cathode” indicates that constant X and coefficient Y are for measurement data at measurement position A, and “anode” is for constant X and coefficient Y for measurement data at measurement position B. It represents that. The measurement position A is a position corresponding to the entrance portion of the oxidant gas flow path, and the measurement position B is a position corresponding to the entrance portion of the fuel gas flow path. In this embodiment (this measurement example), the oxidant gas supply manifold 4 and the fuel gas supply are provided at the peripheral edge of the upper half (one half) of the cell stack 1 as viewed from the stacking direction of the cells 2. A manifold 5 and a cooling fluid supply manifold 8 are formed, and at the periphery of the lower half (the other half) of the cell stack 1, an oxidant gas discharge manifold 7, a fuel gas discharge manifold 6, and A cooling fluid discharge manifold 9 is formed. The oxidant gas supply manifold 4 is closer to the cooling gas supply manifold 8 out of the fuel gas supply manifold 5 and the oxidant gas supply manifold 4, and the fuel gas supply manifold 5 is closer. Are arranged far away (see FIG. 2). For this reason, the temperature at the measurement position A corresponding to the entrance portion of the oxidant gas flow path is higher than the temperature at the measurement position B corresponding to the entrance portion of the fuel gas flow path. Therefore, by distinguishing the two in this way and obtaining the numerical values of the constant X and the coefficient Y, it is possible to appropriately set the conditional expression that the dew point conversion temperature T1 should satisfy for each of the oxidant gas and the fuel gas.

  In these measurement examples, for the oxidant gas (cathode), X is a numerical value in the range of 1.0 to 1.5, Y is a numerical value in the range of 0.02 to 0.027, and fuel gas (anode ), X is 2.0 to 2.5, and Y is 0.02 to 0.023. Therefore, for the reaction gas (oxidant gas or fuel gas), X is a numerical value in the range of 1.0 to 2.5, and Y is a numerical value in the range of 0.02 to 0.027.

In these measurement examples, since the current densities in the two measurement examples are both 0.160 A / cm ² (rated), the dependency of the constant X and the coefficient Y on the current density could not be confirmed. It should be noted that the dependence of the constant X and the coefficient Y on the number N of cells does not exist theoretically or in measured data. This is considered to be the same when cooling every two cells described later.

  Next, consider the case of cooling every two cells.

  In the above description, when cooling every two cells, the dew point converted temperature T1 is preferably equal to or higher than the cooling water inlet temperature T2 + (3 ° C. + 0.02 ° C. × (N−1)). Replenish data and consider in detail.

  15 to 20 are graphs showing other measurement examples of the temperature distribution of the cell stack when cooling is performed every two cells.

15 through 20, respectively, when the current density is 0.300A / cm ^2, when the current density is 0.250A / cm ^2, when the current density is 0.160A / cm ² (nominal) If the current density is 0.116A / cm ^2, when the current density is 0.078A / cm ^2, and the current density showing a measurement example of a case where 0.050A / cm ^2.

  Each of these measurement examples is the same as the measurement example of FIG. 12 except that the number of cells in the cell stack 1 is 54. In addition, although the temperature of the cell in the middle of the cell stack 1 is not shown, this is because the temperature of the cell shows the same tendency as the temperature of the cells at both ends of the cell stack 1, and thus the measurement is omitted. It is.

  However, in these measurement examples, the cell numbers are given in order from the cell 2 close to the cooling water outlet (outside opening of the through hole of the end plate 3B in FIG. 2) 402 to the cell stack 1 (in FIG. 12). This is the opposite of the measurement example). Also, the notation of each plot in FIGS. 15 to 20 is different from the notation of each plot in FIG. That is, in FIGS. 15 to 20, black rhombus marks indicate the temperature at the measurement position A of the separators 10 and 20 shown in FIG. 10, and black square marks indicate the measurements of the separators 10 and 20 shown in FIG. 10. The temperature at position B, the black Δ mark plots the temperature at the measurement position C of the separators 10 and 20 shown in FIG. 10, the black circle mark plots the temperature at the measurement position D of the separators 10 and 20 shown in FIG. The white rhombus plots indicate the temperatures at the measurement position E of the separators 10 and 20 shown in FIG.

  Measurement conditions (experimental conditions) in these measurement examples are as follows.

  In any measurement example, the cooling water inlet temperature T2 is 60 ° C., the cooling water outlet temperature T3 is 68 ° C., and the difference ΔT between the cooling water inlet temperature T2 and the cooling water outlet temperature T3 is 8 ° C.

  15 to 17, the fuel gas utilization rate Uf is 72.5%, and the oxidant gas utilization rate Uo is 52.5%. In the measurement example of FIG. 18, the fuel gas utilization rate Uf is 72.5%, and the oxidant gas utilization rate Uo is 47.5%. In the measurement example of FIG. 19, the utilization factor Uf of the fuel gas is 67.5%, and the utilization factor Uo of the oxidant gas is 42.5%. In the measurement example of FIG. 20, the fuel gas utilization rate Uf is 67.5%, and the oxidant gas utilization rate Uo is 42.5%.

  In any measurement example, the equivalent diameter of each channel (channel groove) of the oxidant gas channel 17 is 0.99 mm, and the equivalent diameter of each channel (channel groove) of the fuel gas channel 28 is It is 0.99 mm.

  In the measurement example of FIG. 17, the flow velocity at the fuel gas flow passage inlet is 4.4 m / s, the flow velocity at the fuel gas flow passage outlet is 2.2 m / s, and the flow velocity at the oxidant gas flow passage inlet is 4.26 m. / S, the flow velocity at the outlet of the oxidizing gas channel is 4.15 m / s. In the measurement example of FIG. 15, the flow velocity at the outlet of the fuel gas channel is 4.1 m / s, and the flow velocity at the outlet of the oxidant gas is 7.7 m / s. Note that the flow rate at the fuel gas flow channel inlet and the flow rate at the oxidant gas flow channel inlet in the measurement example of FIG. 15, and the fuel gas flow channel in the measurement examples of FIGS. 16, 18, 19, and 20. The flow velocity at the inlet, the flow velocity at the flow passage outlet of the fuel gas, the flow velocity at the flow passage inlet of the oxidant gas, and the flow velocity at the flow passage outlet of the oxidant gas are the fuel gas utilization rate Uf and the oxidant gas utilization rate in each measurement example. Since it is possible to calculate from Uo and the current density and each gas flow velocity in the measurement example of FIG. 17, the description is omitted here. The current density in the measurement examples of FIGS. 15 to 20 is as shown in FIG.

  In the measurement example of FIG. 15, the pressure loss of the fuel gas and the pressure loss of the oxidant gas in the cell stack 1 are 13.8 kPa and 11.4 kPa, respectively. In the measurement example of FIG. 16, the pressure loss of the fuel gas and the pressure loss of the oxidant gas in the cell stack 1 are 11.9 kPa and 9.7 kPa, respectively. In the measurement example of FIG. 17, the pressure loss of the fuel gas and the pressure loss of the oxidant gas in the cell stack 1 are 9.6 kPa and 6.0 kPa, respectively. In the measurement example of FIG. 18, the pressure loss of the fuel gas and the pressure loss of the oxidant gas in the cell stack 1 are 5.9 kPa and 4.9 kPa, respectively. In the measurement example of FIG. 19, the pressure loss of the fuel gas and the pressure loss of the oxidant gas in the cell stack 1 are 4.6 kPa and 3.7 kPa, respectively. In the measurement example of FIG. 20, the pressure loss of the fuel gas and the pressure loss of the oxidant gas in the cell stack 1 are 3.6 kPa and 2.7 kPa, respectively.

In the measurement example in the case of cooling every two cells, as in the measurement example in the case of cooling every one cell described above, the conditional expression that the dew point converted temperature T1 should satisfy is:
T1 ≧ T2 + (X ° C. + Y ° C. × (N−1) × ΔT / 8 ° C.).

  The measurement data was statistically processed by the method of least squares, as in the measurement example in the case of cooling for each cell.

  Then, the numerical values of the constant X and the coefficient Y in this conditional expression were obtained from the measurement examples of FIGS. 12 and 15 to 20.

  FIG. 22 is a table showing the numerical values of the constant X and the coefficient Y of the conditional expression to be satisfied by the dew point conversion temperature T1 when cooling is performed every two cells, together with the current density.

  In FIG. 22, experiment numbers 1 to 6 indicate the measurement examples of FIGS. 15 to 20, respectively. The meanings of “cathode” and “anode” are the same as those in FIG.

  In this measurement example, for the oxidant gas (cathode), X is a numerical value in the range of 2.8 to 3.3, Y is a numerical value in the range of 0.013 to 0.033, and fuel gas (anode) X is a numerical value in the range of 3.7 to 4.2, and Y is a numerical value in the range of 0.013 to 0.030. Therefore, for the reactive gas (oxidant gas or fuel gas), X is a numerical value in the range of 2.8 to 4.2, and Y is a numerical value in the range of 0.013 to 0.033.

In these measurement examples, as the current density increases, the constant X generally increases slightly and the coefficient Y decreases. In these measurement examples, since the current density was changed to the limit assumed in actual operation, by appropriately selecting the constant X and the coefficient Y in consideration of the current density within the above numerical range, The conditional expression to be satisfied by the dew point converted temperature T1 can be appropriately set.
<Preferable flow rate and pressure loss of reaction gas>
FIG. 23 is a graph showing an example of the relationship between the gas flow rate and the pressure loss.

  The cell stack used in this measurement example is the same as described above except that the number of cells is 54.

  In FIG. 23, “cathode” represents the pressure loss of the oxidant gas in the cell stack 1, and “anode” represents the pressure loss of the fuel gas in the cell stack 1. In each of the pressure loss curve C and the pressure loss curve A respectively corresponding to “cathode” and “anode”, each plot shows, in order from the smallest gas flow rate, 50% of the rated output when the output is 30% of the rated output. In the case of output, 75% of the rated output and 100% of the rated output are shown.

In the case of 30% of the rated output, the current density is 0.05 A / cm ² , the fuel gas utilization rate Uf is 62.5%, and the oxidant gas utilization rate Uo is 37.5%. In the case of 50% output of the rated output, the current density is 0.078 A / cm ² , the fuel gas utilization rate Uf is 67.5%, and the oxidant gas utilization rate Uo is 42.5%. In the case of 75% of the rated output, the current density is 0.116 A / cm ² , the fuel gas utilization rate Uf is 72.5%, and the oxidant gas utilization rate Uo is 47.5%. In the case of 100% of the rated output, the current density is 0.16 A / cm ² , the fuel gas utilization rate Uf is 72.5%, and the oxidant gas utilization rate Uo is 52.5%.

  As is clear from FIG. 23, the pressure loss of the reaction gas is proportional to the flow rate of the reaction gas. Since the flow rate of the reaction gas is proportional to the flow rate of the reaction gas, the pressure loss of the reaction gas is proportional to the flow rate of the reaction gas. Further, as the current density increases, the flow rate of the reaction gas increases and the pressure loss of the reaction gas increases.

  By the way, the present invention is characterized in that the power generation regions 42A and 42B are maintained in a fully humidified or overhumidified atmosphere over the entire area. Therefore, when the flow velocity of the reaction gas flowing through the flow paths 17 and 28 located in the power generation regions 42A and 42B is lower than a certain value, flooding occurs and the power generation is hindered.

  On the other hand, as shown in FIG. 23, as the flow rate of the reaction gas increases, the pressure loss of the reaction gas in the cell stack 1 increases, and as a result, the pressure required to supply the reaction gas (hereinafter referred to as supply). Pressure)). Therefore, in the present embodiment, the flow velocity at the outlet of the fuel gas passage 28 (the portion where the downstream side of the fuel gas passage 28 intersects the edge of the power generation region 42B) is 1.8 m / s or more and 4.1 m / second. The flow velocity at the outlet of the oxidant gas flow channel 17 (the portion where the downstream side of the oxidant gas flow channel 17 intersects the edge of the power generation region 42A) is 2.8 m / s or more and 7.7 m. / S or less. These lower limit value and upper limit value are determined based on Example 1 described later. In this experiment, five types of cell stacks having the same overall configuration as the cell stack used for the above-described measurement and having different structures of the fuel gas channel 28 and the oxidant gas channel 17 were prepared. And about these cell stacks, by changing the fuel gas utilization rate Uf, the oxidant gas utilization rate Uo, and the current density, the outlet gas flow velocity and the pressure loss are changed, and stable power generation can be performed in each case. Whether or not flooding occurred was determined based on whether or not it occurred.

In this case, the fuel cell 101 has a fuel gas utilization rate of 60% or more, an oxidant gas utilization rate of 40% or more and 80% or less, and a current density of 0.15 A / cm ² or more. And it is assumed that it is operated so that it is 0.30 A / cm ² or less. That is, these gas flow velocity ranges are effective under these operating conditions. The gas flow rate is controlled to increase as the current density increases.

  The control of the flow rates of the fuel gas and the oxidant gas is specifically performed by controlling the fuel gas supply device and the oxidant gas supply device based on the flow rates obtained by the following method.

  If the flow rate of the fuel gas is represented by Qa and the cross-sectional area of the fuel gas flow path 28 is represented by Sa, the flow velocity Va of the fuel gas is Va = Qa / Sa.

  Here, Qa is, for example, the total gas flow rate of the dry base unused fuel gas flow rate at the outlet of the fuel gas passage 28 and the gas flow rate when the total water amount supplied to the anode is calculated as water vapor. The unused fuel gas flow rate is calculated, for example, by subtracting the product of the fuel gas supply amount and the fuel gas utilization rate (Uf) from the fuel gas supply amount. The total amount of water supplied to the anode is calculated from the saturated water vapor pressure at the dew point at the inlet. Specifically, for example, assuming that the saturated water vapor pressure at 60 ° C. is 150 mmHg and the supply pressure is 760 mmHg, 610 mmHg is the partial pressure of the fuel gas, so 150/610 of the supply amount of the fuel gas is the water vapor Amount. Such calculation assumes that all of the supplied water reaches the outlet without condensation, and is suitable for conditions where condensation water is generated only in a part of the fuel gas passage (for example, full humidification). is there. The flow rate may be corrected according to the generation of condensed water.

  Alternatively, Qa is calculated as the total gas flow rate of the dry base unused fuel gas flow rate at the outlet of the fuel gas passage 28 and the steam flow rate calculated from the saturated water vapor pressure at the temperature of the outlet of the fuel gas passage 28. May be. Such calculation assumes that the supplied water is condensed inside and part of it does not reach the outlet as a gas, and the condition where condensed water is generated in the entire fuel gas flow path (over humidification) It is suitable for the case.

  Sa is a cross-sectional area of the fuel gas flow channel 28 in the vicinity of the outlet, and when there are a plurality of flow channels (flow channel grooves), it is the sum of the cross-sectional areas of the respective flow channels (flow channel grooves). Each flow path (flow path groove) has an equivalent diameter (a diameter of a circle having the same cross-sectional area) of 0.78 mm or more and 1.30 mm. The number of the fuel gas flow paths may be different at the inlet and the outlet. In such a case, the number of the fuel gas flow paths at the outlet is multiplied by the cross-sectional area of one flow path, and the outlet flow path on the anode side The cross-sectional area is obtained.

  When the flow rate of the oxidant gas is represented by Qc and the cross-sectional area of the oxidant gas flow path 17 is represented by Sc, the flow rate Vc of the oxidant gas is Vc = Qc / Sc.

Here, Qc is generated by, for example, a dry base unused oxidant gas flow rate at the outlet of the oxidant gas flow path 17, a gas flow rate when the total water amount supplied to the cathode is calculated as water vapor, and a power generation reaction. This is the total gas flow rate with the gas flow rate when the total water content calculated as water vapor. The unused oxidant gas flow rate is calculated, for example, by subtracting the product of the supply amount of the oxidant gas and the utilization rate (Uo) of the oxidant gas from the supply amount of the oxidant gas. The total amount of water supplied to the cathode is calculated from the saturated water vapor pressure at the dew point at the inlet. Specifically, for example, assuming that the saturated water vapor pressure at 60 ° C. is 150 mmHg and the supply pressure is 760 mmHg, 610 mmHg becomes the partial pressure of the oxidant gas, and thus the supply amount of the oxidant gas is 150/610. Is the amount of water vapor. Further, in the fuel cell, two electrons move by the reaction of H ₂ + 1 / 2O ₂ → H ₂ O, so that water molecules are generated by a half of the number of moles of electrons. Therefore, the total amount of water generated by the power generation reaction is obtained by determining the number of moles of electrons generated from the extracted current and determining the number of moles of water generated by the power generation reaction based on the obtained value. Such calculation assumes that all of the supplied water reaches the outlet without condensation, and is suitable for conditions where condensation water is generated only in a part of the fuel gas passage (for example, full humidification). is there. The flow rate may be corrected according to the generation of condensed water.

  Alternatively, Qa is the total gas flow rate of the dry base unused fuel gas flow rate at the outlet of the oxidant gas flow channel 17 and the water vapor flow rate calculated from the saturated water vapor pressure at the temperature of the outlet of the oxidant gas flow channel 17. It may be calculated. Such calculation assumes that the supplied water is condensed inside and part of it does not reach the outlet as a gas, and the condition where condensed water is generated in the entire fuel gas flow path (over humidification) It is suitable for the case.

  Sc is a cross-sectional area of the oxidant gas flow channel 17 in the vicinity of the outlet, and when there are a plurality of flow channels (flow channel grooves), it is the sum of the cross-sectional areas of the respective flow channels (flow channel grooves). Each flow path (flow path groove) has an equivalent diameter of 0.78 mm or more and 1.30 mm. The number of oxidant channels may be different at the inlet and the outlet. In such a case, the number of oxidant channels at the outlet is multiplied by the cross-sectional area of one channel, and the outlet channel on the cathode side The cross-sectional area is obtained.

  Therefore, the fuel gas flow rate Va and the oxidant gas flow rate Vc are controlled by the control device 108 by the fuel gas supply flow rate, the fuel gas utilization rate, the oxidant gas supply flow rate, the oxidant gas utilization rate, and the fuel gas and oxidation rate. It is controlled by controlling the dew point conversion temperature T1 of the agent gas. Such control does not need to be performed by directly measuring the above parameters, and may be controlled as a result by controlling other parameters.

  In the above description, the movement of moisture between the anode and the cathode is ignored, but the flow rate may be corrected in consideration of this. In addition, in the calculation of the flow rate, the accuracy can be improved by appropriately performing necessary corrections.

  Next, the pressure loss of the reaction gas will be described. The pressure loss referred to here indicates a pressure difference (pressure loss at the cell stack) between the fuel gas flow path and the inlet and outlet of the oxidant gas, but actually the inlet (supply manifold) of the cell stack 1 and It is obtained by measuring the pressure of the fuel gas and the oxidant gas at the outlet (exhaust manifold) and obtaining the difference between them.

  In order to prevent flooding, it is preferable that the pressure loss in the reaction gas channels 17 and 28 is large. However, when the pressure loss becomes excessive, the reaction gas supply pressure becomes excessive.

  Therefore, in the present embodiment, the pressure loss of the reaction gas in the cell stack 1 is controlled to be 2 kPa or more and 12 kPa or less. The lower limit value and the upper limit value are determined based on Example 1 described later.

  In the measurement examples of FIGS. 15 and 16, the pressure loss of the reaction gas is out of this preferable range. This is because a special overload operation was performed to collect data on the temperature distribution of the cell stack. Yes, in a cogeneration system, such overload operation is usually not performed.

  As described above, by controlling the flow rate of the reaction gas and the pressure loss of the reaction gas, the power generation regions 42A and 42B are maintained in a fully humidified or overhumidified atmosphere over the entire region while preventing the occurrence of flooding. be able to.

In the above description, the outlet of the fuel gas passage 28 is a portion where the downstream side of the fuel gas passage 28 intersects the edge of the power generation region 42B, and the outlet of the oxidizing gas passage 17 is the oxidant gas. The downstream side of the flow path 17 was a part that intersects the edge of the power generation region 42A. However, the outlet refers to the most downstream portion of the groove-like gas flow path provided in the separator. That is, the exit is not necessarily limited to a portion that intersects the edge of the power generation device, and may be in the vicinity thereof. For example, the outlet of the fuel gas passage 28 may be a portion where the fuel gas passage 28 communicates with the outlet manifold hole of the fuel gas, and the outlet of the oxidant gas passage 17 is the oxidant gas passage. 28 may be a portion communicating with the outlet manifold hole for the oxidant gas. The downstream side refers to the downstream side along the gas flow. Thus, the main reason for paying attention to the flow velocity in the most downstream portion is as follows. That is, hydrogen, which is a fuel, is consumed at the anode in accordance with the reaction at the electrode, and the partial pressure of water vapor is relatively increased, so that dew condensation water is likely to be generated, and the flow rate is slow. In the cathode, water is generated according to the reaction at the electrode, and the partial pressure of water vapor is relatively increased, so that condensed water is likely to be generated.
<Effective range for fuel cell ratings>
The study on the conditional expression to be satisfied by the above dew point conversion temperature T1 was performed using a fuel cell having a rated output of DC 1.2 kW. However, this study result is theoretically applicable (effective) to fuel cells having different rated outputs. Specifically, the present invention can be applied almost certainly to a fuel cell having a rated output of DC 0.4 kW to 2.4 kW. Furthermore, for example, by simply increasing the number of stacked cells in the cell stack, it can be applied to a fuel cell with a rated output of DC 5 kW.

  From the above viewpoint, the operating conditions of the fuel cell power generation system are summarized as follows.

In the operation of the fuel cell power generation system 101,
It is preferable to satisfy T1 ≧ T2 + 1 ° C. (operating condition 1).

  Furthermore, T1 ≧ T2 + (X ° C. + Y ° C. × (N−1) × ΔT / 8 ° C.) However, X = 1 to 2.5 and Y = 0.02 to 0.027 (operating condition 2) are satisfied. Is preferred.

  Moreover, it is preferable to satisfy T3-T2 ≦ 15 ° C. (operating condition 3), and further satisfy T3-T2 ≦ 10 ° C. (operating condition 4).

  Moreover, it is preferable to satisfy T2 ≦ T1 ≦ T3 (operating condition 5).

  Moreover, it is preferable to satisfy T3-T1 ≧ 1 ° C. (operating condition 6).

  Further, it is preferable that 90 ° C. ≧ T3 ≧ 66 ° C. (operating condition 7), T1 ≧ 50 ° C. (operating condition 8), and 80 ° C. ≧ T3 ≧ 66 ° C. (operating condition 9).

  Further, in the case of adopting the two-cell cooling method, T1 ≧ T2 + (X ° C. + Y ° C. × (N−1) × ΔT / 8 ° C.) However, X = 2.8 to 4.2 and Y = 0. It is preferable to satisfy 013 to 0.033 (operating condition 10).

  Based on the above knowledge, in the present embodiment, the fuel cell power generation system 100 is configured so as to satisfy (Operating Condition 1) to (Operating Condition 9).

  Specifically, in FIG. 1 to FIG. 9, in the cathode side separator 10 and the anode side separator 20, the reaction gas passages 17 and 28 and the cooling water passages 19 and 29 are formed in a “reaction gas temperature rising gradient arrangement”. Yes. Further, for the humidification and heating of the reaction gas, the supply reaction gas and the exhaust reaction gas are humidified and heated by total heat exchange, and further, this heat and heat exchange is performed for total heat exchange between the humidified and heated supply reaction gas and the exhaust cooling water. By using the vessels 117 and 118, the heat exchangeable temperature difference T3-T1 is about 1 ° C. Further, the maximum cooling capacity of the cooling system 104 with respect to the maximum heat generation amount of the cell stack 1 so that the temperature difference between the cooling water outlet temperature T3 and the cooling water inlet temperature T2 can satisfy the condition of T3−T2 ≦ 10 ° C. Is set. Then, the temperature of the cooling water is adjusted so that the cooling water outlet temperature T3 satisfies the condition of 80 ° C. ≧ T3 ≧ 66 ° C. At this time, a specific coolant outlet temperature T3 is determined in consideration of a predetermined output current density of the fuel cell 101. The temperature adjustment of the cooling water is performed by the control device 108 controlling at least one of the heat radiation amount of the heat radiating device 105 of the cooling system 104 and the flow rate of the cooling water circulation pump 109. The temperature control of the cooling water is performed by the control device 108 based on the detected values of the temperature sensor TS1 and the temperature sensor TS2 that detect the cooling water inlet temperature T2 and the cooling water outlet temperature T3, respectively. This is accomplished by feedback control of the water outlet temperature T3.

  In addition, each flow path (flow path groove) in the oxidant gas flow path 17 and the fuel gas flow path 28 is formed to have an equivalent diameter of 0.78 mm to 1.30 mm or less. Further, the control device 108 controls the oxidant gas supply device 103 so that the flow rate of the oxidant gas in the oxidant gas flow path 17 is in the range of 2.8 m / s to 7.7 m / s. The oxidant gas is supplied so that the pressure loss becomes 2 kPa to 10 kPa. Further, the control device 108 controls the fuel gas supply device 102 so that the flow rate of the fuel gas in the fuel gas passage 28 is in the range of 1.8 m / s to 4.1 m / s, and the pressure loss in the cell stack 1 is reduced. Fuel gas is supplied so that it may become 2 kPa-10 kPa.

  Next, the operation of the fuel cell power generation system 100 configured as described above will be described. The fuel cell power generation system 100 operates under the control of the control device 108 and has a start mode, an operation mode, and a stop mode. In the startup mode, the fuel cell power generation system 100 is smoothly started by sequentially performing predetermined startup operations. In the operation mode (during power generation operation), normal power generation is performed. In the stop mode, the fuel cell power generation system 100 is smoothly stopped by sequentially performing a predetermined stop operation. In the present embodiment, since a well-known operation is performed in the start mode and the stop mode, description thereof will be omitted, and only the operation mode will be described below.

  1 to 9, in the operation mode, fuel gas (supplied fuel gas) is supplied from the fuel gas supply device 102 to the anode 42 </ b> B of the fuel cell 101. On the other hand, an oxidant gas (supply oxidant gas) is supplied from the oxidant gas supply device 103 to the cathode 42 </ b> A of the fuel cell 101. Then, a power generation reaction occurs in the anode 42B and the cathode 42A, and electric power and heat (exhaust heat) are generated. Unreacted fuel gas (exhaust fuel gas) and oxidant gas (exhaust oxidant gas) that have not been consumed by the power generation reaction are discharged from the fuel cell 101. On the other hand, the fuel cell 101 is cooled by the cooling water circulating through the cooling water circulation passage 112 of the cooling system 104.

  In this process, the supplied fuel gas undergoes total heat exchange with the exhaust fuel gas in the anode-side total heat exchanger 117, and further undergoes total heat exchange with the cooling water (exhaust cooling water) after passing through the fuel cell 101, and the fuel. Humidification and heating are performed so that the dew point converted temperature (inlet dew point converted temperature) T1 at the inlet of the battery 101 becomes a predetermined value.

  On the other hand, the supplied oxidant gas undergoes total heat exchange with the exhaust oxidant gas in the cathode-side total heat exchanger 118, and further undergoes total heat exchange with the exhaust cooling water so that the inlet dew point converted temperature T1 becomes a predetermined value. Humidified and heated.

  Further, the control device 108 controls the heat radiation amount of the heat radiating device 105 of the cooling system 104 and the flow rate of the cooling water circulation pump 106 based on the detected values of the inlet temperature sensor TS1 and the outlet temperature sensor TS2, and the cooling water inlet temperature T2 and Adjust the cooling water outlet temperature T3. In this case, the cooling water inlet temperature T2 is determined according to the cooling capacity (heat radiation amount) of the cooling system with respect to the heat generation amount of the fuel cell 101, and the cooling water inlet temperature T2 and the cooling water outlet temperature T3 are determined according to the flow rate of the cooling water. A temperature difference ΔT is determined. Further, when the cooling water outlet temperature T3 is determined, the supply fuel gas and the supply oxidant gas substantially change according to the heat exchangeable temperature difference T3-T1 between the anode-side total heat exchanger 117 and the cathode-side total heat exchanger 118. The inlet dew point conversion temperature T1 is determined. That is, by controlling the heat radiation amount of the heat radiating device 105 of the cooling system 104 and the flow rate of the cooling water circulation pump 106, the cooling water outlet temperature T3, the cooling water inlet temperature T2, and the fuel gas and oxidant gas inlet dew point conversion temperature T1. Can be controlled. In addition, since the amount of exhaust heat of the fuel cell 101 changes according to the fluctuation of the output of the fuel cell 101, the control device 108 changes the cooling capacity of the cooling system 104 according to the change of the amount of exhaust heat, while the cooling water described above. Temperature control. In this way, under the control of the control device 108, the fuel cell power generation system 100 is operated so as to satisfy the above-mentioned (operation condition 1) to (operation condition 9) in the operation mode. Thereby, the region where power generation of the fuel cell 101 occurs is maintained in a full humidified or over humidified atmosphere over the entire region. As a result, deterioration of the polymer electrolyte membrane 41 of the MEA 43 is suppressed, and the life of the fuel cell 101 is improved.

  Next, the effect of the above-described characteristic configuration in the present embodiment will be described based on the experimental result of Example 2 described later.

  FIG. 13 is a graph showing the results of a life test of the fuel cell. In FIG. 13, the horizontal axis indicates the operation time, and the vertical axis indicates the cell voltage.

  In this experiment, as an example of the present embodiment, the hardware is the fuel cell power generation system 100 created according to the present embodiment except for the total heat exchangers 117 and 118, and the operating condition is the first operating condition. And by switching between the second operating conditions. In the fuel cell power generation system 100 of the present embodiment, a bubbler is used instead of the total heat exchangers 117 and 118, and the fuel gas and the oxidant gas are humidified and humidified by this bubbler so that the predetermined inlet dew point conversion temperature T1 is obtained. Warm up. Therefore, the inlet dew point converted temperature T1 of the fuel gas and the oxidant gas was appropriately controlled as in the case of operating the fuel cell system 100 of the present embodiment (FIG. 1). The flow rate of the fuel gas in the fuel gas channel 28 is controlled to be in the range of 1.8 m / s to 4.1 m / s, and the flow rate of the oxidant gas in the oxidant gas channel 17 is 2.8 m / s. The pressure loss of the oxidizing gas and the fuel gas in the cell stack 1 was controlled to be 2 kPa to 10 kPa.

  Here, the first operating condition is an operating condition as a comparative example that does not satisfy T1 ≧ T2 + 1 ° C. (operating condition 1). Specifically, the cooling water inlet temperature T2 is 64 ° C., and the cooling water outlet temperature T3. Is 69 ° C., and the fuel gas and oxidant gas inlet dew point conversion temperature T 1 is 64 ° C. The second operating condition is T1 ≧ T2 + (X ° C. + Y ° C. × (N−1) × ΔT / 8 ° C.) where X = 1 to 2.5 and Y = 0.02 to 0.027 (operating condition 2 (And operating condition 1)), specifically, the cooling water inlet temperature T2 is 61 ° C., the cooling water outlet temperature T3 is 69 ° C., and the fuel gas and oxidant gas inlet dew points. The conversion temperature T1 is 64 ° C.

  The fuel cell power generation system 100 was operated under a first operating condition that did not satisfy (Operating Condition 1) in a period P1 from the start of operation until approximately 4400 hours passed. Then, the cell voltage gradually decreased. After that, in a period P2 of about 400 hours, the operation was performed under the second operation condition satisfying (operation condition 2 (and operation condition 1)). Then, the cell voltage increased (recovered). Thereafter, in the period P3 of about 400 hours, the operation was performed again under the first operation condition that does not satisfy (operation condition 1). Then, the cell voltage gradually decreased again. Thereafter, in a period P4 from the start of operation until about 9400 hours passed, the operation was performed again under the second operation condition satisfying (operation condition 2 (and operation condition 1)). Then, the cell voltage recovered again, and the cell voltage was maintained even after about 9400 hours had elapsed from the start of operation.

  From this fact, it is predicted that the performance (cell voltage) of the fuel cell 101 is lowered and the life of the fuel cell 101 is shortened when the conventional operation method is used, whereas the operation method (operating condition 1) of the present invention is predicted. When the operation method satisfying (1) and (2) is used, it has been proved that the performance of the fuel cell 101 once lowered is maintained as it is, and the life of the fuel cell 101 is improved.

In the above description, the operation is performed under the condition that condensed water is generated in both the anode (or the fuel gas channel) and the cathode (or the oxidant gas channel). ) And at least one of the cathode (or the oxidant gas flow path) may be a condition in which condensed water is generated. Even under such conditions, the effects of the present invention such as prevention of flooding and prevention of deterioration of the polymer electrolyte membrane can be obtained.
Example 1
In this example, a fuel cell power generation system having the configuration shown in FIGS. 1 to 9 was produced.

  In FIG. 1 to FIG. 9, only the specific configuration of the fuel cell 101, the anode-side total heat exchanger 117, and the cathode-side total heat exchanger 118 is shown here. The other parts are configured as known.

  First, a method for manufacturing the anode 42B and the cathode 42A (hereinafter referred to as an electrode) will be described.

  A catalyst in which 25% by weight of platinum particles having an average particle diameter of about 30 mm were supported on acetylene black powder was used as a catalyst. A catalyst paste was prepared by mixing a dispersion solution in which perfluorocarbon sulfonic acid was dispersed in ethyl alcohol with a solution in which the catalyst powder was dispersed in isopropanol.

On the other hand, carbon cloth (TGP-H-090 manufactured by TORAY) having an outer size of 12 cm × 12 cm and a thickness of 220 μm constituting the gas diffusion layer was subjected to water repellent treatment. A carbon black powder (DENKA BLACKFX-35 manufactured by Denki Kagaku Kogyo Co., Ltd.) and a PTFE aqueous dispersion (Daikin D-1) were applied to the surface of the carbon cloth catalyst layer. A water repellent layer was applied by baking at 400 ° C. for 30 minutes. A catalyst layer was formed on the surface of the carbon cloth provided with the water repellent layer by applying a catalyst paste using a screen printing method. And the carbon cloth in which this catalyst layer was formed was used as an electrode. The amount of platinum contained in the electrode on which this catalyst layer was formed was 0.3 mg / cm ² , and the amount of perfluorocarbon sulfonic acid was 1.0 mg / cm ² .

  Next, as the polymer electrolyte membrane 41, a perfluorocarbon sulfonic acid membrane (Nafion 112 (registered trademark) manufactured by DUPONT) having an outer dimension of 20 cm × 20 cm was used. A pair of electrodes was joined to both surfaces of the polymer electrolyte membrane 41 by hot pressing so that the catalyst layer was in contact with the polymer electrolyte membrane 41, thereby producing the MEA 43. Here, as the polymer electrolyte membrane, a perfluorocarbon sulfonic acid thinned to a thickness of 30 μm was used.

  Next, 80 wt% of artificial graphite powder having an average particle size of 100 μm, 5 wt% of carbon black, and 15 wt% of phenol resin before thermosetting were mixed to prepare a compound. This compound is put into a mold having a shape in which the shape of the separator is transferred, and the phenol resin is cured by hot pressing at 180 ° C., whereby the conductive molded separators 10 and 20 shown in FIGS. Was made. 4 and 6 schematically show the shapes of gas flow grooves (flow channel grooves) formed on the front surfaces (inner surfaces) of the separators 10 and 20. FIG. 24 is a table showing parameters of the fuel cell created in Example 1. The separators 10 and 20 have a size of 20 cm × 20 cm and a thickness of 3 mm, the reaction gas channels 17 and 28 have a rectangular cross section, the channel groove width, the channel groove depth, and the outlet channel. As shown in FIG. 24, five patterns from type A to type E were prepared for the number of grooves, the channel cross-sectional area of the outlet portion, and the equivalent diameter.

  Next, oxidant gas manifold holes 21 and 23 and fuel gas manifold holes 22 and 24 were formed in the separators 10 and 20.

  5 and 7 show the shapes of the cooling water passages 19 and 29, which are formed on the back surface (outer surface) of the separator 19 shown in FIGS. The cooling water channels 19 and 29 are formed in a groove shape having a depth of 0.7 mm.

  Next, manifold holes for circulating cooling water, fuel gas, and oxidant gas are formed in the polymer electrolyte membrane 41 of the MEA 43, and the periphery of the electrode portion at the center of the MEA 43 and the periphery of the manifold holes 11-16. In addition, an O-ring fluid seal member made by Viton was bonded to form a gasket.

The MEA 43 was sandwiched between the anode-side separator 20 and the cathode-side separator 10 created in this way, and a cell 2 was created. A cell laminate 201 was prepared by laminating 40 cells 2. Then, at both ends of the cell laminate 201, a current collector plate plated with gold on the surface of copper, an insulating plate made of PPS, and end plates 3A and 3B created by cutting SUS are disposed. Fixed with a fastening rod. The fastening pressure at this time was 10 kgf / cm ² per electrode area.
Thus, the fuel cell 101 (cell stack 1) was produced.

  In this experiment, using the fuel cell 101 described above, a fuel cell power generation system was created according to the present embodiment except for the total heat exchangers 117 and 118. In the fuel cell power generation system of the present embodiment, a bubbler is used instead of the total heat exchangers 117 and 118, and the fuel gas and the oxidant gas are humidified and made to reach a predetermined inlet dew point conversion temperature T1 by this bubbler. Warmed up. Therefore, the inlet dew point converted temperature T1 of the fuel gas and the oxidant gas was appropriately controlled as in the case of operating the fuel cell system 100 of the present embodiment (FIG. 1).

  The fuel cell power generation system using the type A to E separator having the above-described configuration was operated under the following conditions.

The operating conditions are T1 ≧ T2 + (X ° C. + Y ° C. × (N−1) × ΔT / 8 ° C.) where X = 1 to 2.5 and Y = 0.02 to 0.027 (operating condition 2 (and driving The operating conditions of the present invention satisfying the condition 1)). Specifically, the cooling water inlet temperature T2 is 61 ° C., the cooling water outlet temperature T3 is 69 ° C., and the fuel gas and oxidant gas inlet dew point conversion temperature T1. Was 64 ° C. Then, the current density was operated in the range of 0.06 to 0.2 A / cm ² (the current density and the flow velocity are almost proportional), and it was determined whether flooding (unstable voltage generation) occurred. . The fuel gas utilization rate (Uf) and the oxidant gas utilization rate (Uo) were adjusted by the balance between the amount of current extracted from the fuel cell and the amount of gas supplied. Each type of Uf and Uo was as shown in FIG. 24 (Uf was 60% or more, Uo was 40% or more and 80% or less). The pressure loss was determined from the difference between the gas inlet (supply manifold) and outlet (exhaust manifold) pressures measured into the cell stack.

  The obtained results are shown in FIG. 25 and FIG. FIG. 25 is a graph showing the relationship between the flow velocity at the outlet on the anode side and the pressure loss of the fuel gas. FIG. 26 is a graph showing the relationship between the flow velocity at the outlet on the cathode side and the pressure loss of the fuel gas. In the figure, the circled circles (◯) indicate that power generation is possible stably (voltage is stable), that is, no flooding has occurred. A plot indicated by a triangle (Δ) indicates that power generation is unstable (an unstable voltage is generated, for example) due to the occurrence of flooding. Plots with crosses indicate that power generation is impossible due to the occurrence of flooding (voltage cannot be lowered to extract power). In this example, since it is a condition (excessive humidification) that dew condensation water is generated on the entire surface of the anode and the cathode, the flow velocities Va and Vc were obtained from the following equations.

Va = (fuel gas supply amount−fuel gas supply amount × Uf + saturated water vapor amount at outlet temperature) / outlet channel cross-sectional area Vc = (oxidant gas supply amount−oxidant gas supply amount × Uo + saturated water vapor amount at outlet temperature) As shown in FIG. 25, on the anode side, it is clear that the flow velocity at the outlet is preferably 1.8 m / s or more. Further, as can be seen from FIG. 26, it is clear that the flow velocity at the outlet is preferably 2.8 m / s or more on the cathode side. It is clear that the pressure loss is preferably 3.6 kPa to 10 kPa for the anode and 2 kPa to 10 kPa for the cathode. Therefore, when the fuel gas and the oxidant gas are grasped by the superordinate concept of the reaction gas, the pressure loss is preferably 2.0 kPa or more. From the viewpoint of preventing flooding, the pressure loss is preferably as high as possible, and the upper limit thereof may be, for example, 13.8 kPa or less for the anode and 11.4 kPa or less for the cathode. Further, the upper limit of the flow rate on the anode side was 4.1 m / s or less, and the upper limit of the flow rate on the cathode side was 7.7 m / s or less. The upper limit values of the flow velocity and pressure loss were determined based on empirical rules from the viewpoint of performance related to the reaction gas supply pressure of an auxiliary machine (here, a fuel supply pump and an oxidant gas supply blower).
(Example 2)
Using the fuel cell power generation system 100 of the present example produced in the same manner as in Example 1, the life test described in Embodiment 1 based on FIG. 13 was performed.

  As a result, as described in the first embodiment, the life of the fuel cell 101 can be improved.

  In the first embodiment, the reaction gas is humidified and heated so as to have a predetermined inlet dew point converted temperature by total heat exchange with at least one of the reaction gas discharged from the fuel cell 101 and the cooling water. This may be performed using a general humidifier such as a bubbler.

  In the first embodiment, the anode-side total heat exchangers 117, 119, and 121 and the cathode-side total heat exchangers 118, 120, and 122 are separated, but they may be integrated. These may be integrated with the cell stack 1. In this case, the anode-side total heat exchangers 117, 119, and 121, the cathode-side total heat exchangers 118, 120, and 122, and the cell stack 1 have the same basic configuration, so they are easily integrated. be able to.

  In the first embodiment, the anode side total heat exchangers 117 and 121 and the cathode side total heat exchangers 118 and 22 are connected in parallel to the cooling circulation channel 112 of the cooling system 104. The devices 117 and 121 and the cathode-side total heat exchangers 118 and 22 may be connected in series to the cooling circulation passage 112 of the cooling system 104.

  Moreover, in the said Embodiment 1, although the cooling water flow paths 19 and 29 were provided for every 1 or 2 cells, you may provide this for every 3 or more cells.

  The polymer electrolyte fuel cell power generation system according to the present invention can reliably prevent flooding while sufficiently suppressing deterioration of the polymer electrolyte membrane of the polymer electrolyte fuel cell power generation system based on a simple configuration. It is useful as a polymer electrolyte fuel cell power generation system.

FIG. 1 is a block diagram schematically showing a configuration of a polymer electrolyte fuel cell power generation system according to Embodiment 1 of the present invention. FIG. 2 is a perspective view showing a schematic configuration of the fuel cell of FIG. 1. It is sectional drawing along the III-III plane of FIG. It is a front view of a cathode side separator. It is a rear view of a cathode side separator. It is a front view of an anode side separator. It is a rear view of an anode side separator. It is a perspective view which shows the structure of the total heat exchange cell stack which comprises the anode side total heat exchanger of FIG. It is sectional drawing along the IX-IX plane of FIG. It is a schematic diagram which shows the structure of the separator used in order to measure the temperature distribution of a cell stack. It is a graph which shows the temperature distribution of the cell stack at the time of cooling for every cell. It is a graph which shows the temperature distribution of the cell stack at the time of cooling every 2 cells. It is a graph which shows the result of the life test of the fuel cell by Embodiment 1 of this invention. It is a graph which shows the other example of a temperature distribution of the cell stack at the time of cooling for every cell. It is a graph which shows the other example of a temperature distribution of the cell stack at the time of cooling every 2 cells. It is a graph which shows the other example of a temperature distribution of the cell stack at the time of cooling every 2 cells. It is a graph which shows the other example of a temperature distribution of the cell stack at the time of cooling every 2 cells. It is a graph which shows the other example of a temperature distribution of the cell stack at the time of cooling every 2 cells. It is a graph which shows the other example of a temperature distribution of the cell stack at the time of cooling every 2 cells. It is a graph which shows the other example of a temperature distribution of the cell stack at the time of cooling every 2 cells. It is a table | surface which shows the numerical value of the constant X of the conditional expression which should satisfy | fill with the dew point conversion temperature T1 at the time of cooling for every cell, and the coefficient Y with a current density. It is a table | surface which shows the numerical value of the constant X of the conditional expression which should satisfy | fill with the dew point conversion temperature T1 at the time of cooling every 2 cells, and the coefficient Y with a current density. It is a graph which shows an example of the relationship between a gas flow rate and a pressure loss. 3 is a table showing parameters of a fuel cell created in Example 1. It is a graph which shows the relationship between the flow velocity in the exit on the anode side, and the pressure loss of fuel gas. It is a graph which shows the relationship between the flow velocity in the exit by the side of a cathode, and the pressure loss of fuel gas.

Explanation of symbols

DESCRIPTION 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 separators 11, 21 Oxidation Agent gas inlet manifold holes 13 and 23 Oxidant gas outlet manifold holes 17 Oxidant gas flow path 20 Anode-side separators 12 and 22 Fuel gas inlet manifold holes 14 and 24 Fuel gas outlet manifold holes 15 and 25 Cooling water Inlet manifold holes 16, 26 Cooling water outlet manifold holes 19, 29 Cooling water flow path 28 Fuel gas flow path 30 Cooling water supply pipe 41 Polymer electrolyte membrane 42A Cathode 42B Anode 43 MEA
46 Gasket 48 O-ring 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 100 Fuel cell power generation system 101 Fuel cell 102 Fuel gas supply device 103 Oxidant gas supply Device 104 Cooling system 105 Heat dissipating device 106 Cooling water circulation pump 107 Oxidant gas discharge passage 108 Control device 109 Fuel gas supply passage 110 Fuel gas discharge passage 111 Oxidant gas discharge passage 112 Cooling water circulation passage 117 Anode side total heat Exchanger 118 Cathode side total heat exchanger 202 Total heat exchange cells 203A, 203B End plate 204 First fluid supply manifold 205 Second fluid supply manifold 206 Second fluid discharge manifold 207 First fluid discharge manifold 210 First Separators 211,2 1 First fluid inlet manifold holes 213, 223 First fluid outlet manifold holes 217 First fluid flow path 220 Second separator 212, 222 Second fluid inlet manifold holes 214, 224 Second fluid Outlet manifold hole 228 Second fluid flow path 243 Pseudo-MEA
251 First fluid supply pipe 252 First fluid discharge pipe 253 Second fluid supply pipe 254 Second fluid discharge pipe 301 Total heat exchange cell stack 301A First total heat exchange cell stack 301B Second total heat exchange Cell stack 301C Third total heat exchange cell stack 301D Fourth total heat exchange cell stack 302 Total heat exchange cell stack 303A Anode-side cooling water heat exchanger 303B Cathode-side cooling water heat exchanger 401 Cooling water circulation channel The fuel cell inlet 402 to the fuel cell outlet 403 Fuel gas inlet 404 Oxidant gas inlet 500 Humidifier fuel cell 501 Humidifier and fuel cell integrated stack 502 Battery part 503 Humidifier part 504A, 504B End plate 510 First separator 511 Supply oxidant gas flow path 512 Supply fuel gas flow path 520 First 2 separator 521 exhaust oxidant gas flow path 522 exhaust fuel gas flow path TS1 inlet temperature sensor TS2 outlet temperature sensor

Claims (9)

A polymer electrolyte membrane; an anode as an electrode disposed on one surface of the polymer electrolyte membrane; an anode as an electrode disposed on the other surface of the polymer electrolyte membrane; and a fuel gas to the anode A unit component composed of an anode side separator having a fuel gas flow path for supplying and discharging gas and a cathode side separator having an oxidant gas flow path for supplying and discharging oxidant gas to the cathode, and A polymer electrolyte fuel cell that is operated under conditions where dew condensation water is generated in at least a part of a fuel gas channel or the oxidant gas channel,
When operating at a fuel utilization rate of 60% or more, an oxidant utilization rate of 40% or more and 80% or less, and a current density in the range of 0.15 A / cm ^{2 to} 0.3 A / cm ² ,
The gas flow velocity Va at the outlet of the fuel gas flow path is 1.8 m / s or more and 4.1 m / s or less,
A polymer electrolyte fuel cell, wherein a gas flow velocity Vc at an outlet of the oxidant gas flow path is 2.8 m / s or more and 7.7 m / s or less. A polymer electrolyte fuel cell according to claim 1;
A fuel gas supply device for supplying fuel gas to the polymer electrolyte fuel cell;
An oxidant gas supply device for supplying an oxidant gas to the polymer electrolyte fuel cell;
A control device,
The control device has a fuel utilization rate of 60% or more, an oxidant utilization rate of 40% or more and 80% or less under the condition that condensed water is generated in at least a part of the fuel gas passage or the oxidant gas passage. , When operating so that the current density falls within the range of 0.15 A / cm ^{2 to} 0.3 A / cm ² ,
Controlling the fuel gas supply device so that the gas flow velocity Va at the outlet of the fuel gas flow path is in the range of 1.8 m / s to 4.1 m / s,
A polymer electrolyte fuel cell power generation system that controls the oxidant gas supply device so that the gas flow velocity Vc at the outlet of the oxidant gas flow path falls within a range of 2.8 m / s to 7.7 m / s. .   The fuel gas flow rate Va at the outlet of the fuel gas flow channel operates so that the thermodynamic condition in which condensed water is generated is satisfied throughout the fuel gas flow channel. Sa is the sum of the cross-sectional areas of the gas flow passages at the portion where the downstream side of the passage intersects the peripheral edge of the power generation region, and the amount of saturated water vapor at the anode outlet dry base unused fuel gas flow rate calculated from the fuel utilization rate and the anode outlet temperature The polymer electrolyte fuel cell according to claim 1, wherein the total gas flow rate is Qa, and is obtained by the formula Va = Qa / Sa.   The thermodynamic condition in which condensed water is generated operates so that the entire oxidant gas flow path is satisfied, and the gas flow velocity Vc at the outlet of the oxidant gas flow path is an oxidation that communicates with the outlet manifold of the cathode separator. Sc is the sum of the cross-sectional areas of the gas flow path at the portion where the downstream side of the oxidant gas flow path intersects the peripheral edge of the power generation region, and the dry oxidant gas flow rate of the dry base at the cathode outlet calculated from the oxidant utilization rate and the cathode outlet 2. The polymer electrolyte fuel cell according to claim 1, wherein the total gas flow rate with the saturated water vapor amount at temperature is Qc, and is obtained by the formula Vc = Qc / Sc.   The fuel gas flow rate Va at the outlet of the fuel gas flow channel operates so that a thermodynamic condition in which condensed water is generated is satisfied by at least a part of the fuel gas flow channel. Sa is the sum of the cross-sectional areas of the gas flow path at the portion where the downstream side of the gas flow path intersects the peripheral edge of the power generation region, the flow rate of the unused fuel gas at the dry base at the anode outlet calculated from the fuel utilization rate, and the total supplied to the anode 2. The polymer electrolyte fuel cell according to claim 1, wherein the total gas flow rate with respect to the gas flow rate when the water content is calculated as water vapor is Qa, and is obtained by the formula Va = Qa / Sa.   The thermodynamic condition in which condensed water is generated operates so that at least a part of the oxidant gas flow path is satisfied, and the gas flow velocity Vc at the outlet of the oxidant gas flow path communicates with the outlet manifold of the cathode separator. Sc is the total sum of the gas channel cross-sectional areas of the portion where the downstream side of the oxidizing gas channel intersects the peripheral edge of the power generation region, and the dry base unused oxidizing gas flow rate calculated from the oxidizing agent utilization rate The total gas flow rate of the gas flow rate when the total water amount supplied to the cathode is calculated as water vapor and the gas flow rate when the total water amount generated by the cell reaction is calculated as water vapor is Qc, and the equation Vc = Qc / Sc The polymer electrolyte fuel cell according to claim 1, which is required. A cooling fluid path through the fuel cell;
A cooling fluid supply device for supplying a cooling fluid to the cooling fluid path;
A control device,
When the power generation is performed, the control device represents a temperature (hereinafter referred to as an inlet dew point converted temperature) in which the total moisture amount at the inlet of at least one of the fuel gas and the oxidant gas is converted to a dew point, and is represented by T1. 2. The polymer according to claim 1, wherein the cooling fluid supply device is controlled to satisfy a condition of T1 ≧ T2 + 1 ° C. when a temperature at a cooling fluid inlet (hereinafter referred to as a cooling fluid inlet temperature) is represented by T2. Electrolytic fuel cell.   2. The polymer electrolyte fuel cell according to claim 1, which operates so that a thermodynamic condition in which condensed water is generated is satisfied over the entire surface of the anode and the cathode. The polymer electrolyte fuel cell according to claim 1, wherein a pressure loss of at least one of the supply gas on the anode side and the cathode side is 2 kPa or more and 10 kPa or less.

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