JP2006049133A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance output density to a system scale and efficiently make an external humidifying fuel cell generate electric power and an internal humidified fuel cell. <P>SOLUTION: A fuel cell system has the external humidifying fuel cell 1 and the internal humidifying fuel cell 2; and when electric power is generated by supplying air, in starting, in cooling the cell, in starting at freezing point, at generation of water clogging, or the like, air is supplied to the external humidifying fuel cell 1; air exhausted from the external humidifying fuel cell 1 is supplied to the internal humidifying fuel cell 2, and in the normal power generation, air is supplied to the internal humidifying fuel cell 2, and air exhausted from the internal humidifying fuel cell 2 is supplied to the external humidifying fuel cell 1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell system that includes a plurality of fuel cells having different structures and controls power generation of each fuel cell in accordance with the state of the fuel cell.

  In a fuel cell, a fuel gas such as hydrogen gas and an oxidizing gas containing oxygen are electrochemically reacted through an electrolyte, and electric energy is directly taken out between electrodes provided on both surfaces of the electrolyte. In particular, a polymer electrolyte fuel cell using a polymer electrolyte has attracted attention as a power source for electric vehicles because of its low operating temperature and easy handling. That is, a fuel cell vehicle has a hydrogen storage device and a fuel reformer mounted on the vehicle, and hydrogen supplied from the vehicle and oxygen-containing air are sent to the fuel cell to react with each other, and the electric energy extracted from the fuel cell is obtained. It drives the motor connected to the drive wheels, and it is the ultimate clean vehicle without the emission of air pollutants.

  By the way, the solid polymer electrolyte membrane used in the polymer electrolyte fuel cell does not exhibit good hydrogen ion conductivity unless it is kept in a wet state. In order to maintain the solid polymer membrane in a wet state, an external humidification method in which fuel gas or oxidant gas is humidified by a humidifier provided outside the fuel cell, or a pure water passage for humidification is provided inside the fuel cell. There is an internal humidification method in which fuel gas or oxidant gas is humidified through this pure water passage and a porous water permeable plate. The former humidification method is called an external humidification fuel cell, and the latter is called an internal humidification fuel cell.

As a fuel cell system provided with such an internal humidification type fuel cell, a technique including a fuel electrode, an oxidant electrode and an electrolyte membrane, and maintaining the wet state of the electrolyte membrane and suppressing internal flooding is disclosed in the following patent document. 1 and so on.
JP 2004-146247 A

  However, in the conventional external humidification fuel cell, it is necessary to provide a humidifier separately from the fuel cell main body, the volume of the fuel cell system increases, the output density with respect to the volume of the fuel cell system and the vehicle mountability There has been a problem of lowering. In addition, since energy for humidifying the reaction gas is required by the humidifier, there is a problem in that the fuel efficiency performance of the fuel cell system as a whole is reduced. Furthermore, in the external humidification type fuel cell, water clogging is likely to occur at the time of starting to start power generation or at the time of cooling, and there is no problem even if it is not humidified at the time of starting below the freezing point.

  Further, the conventional internal humidification type fuel cell has a problem that the start-up time becomes long because moisture remains in the pure water passage at the start-up.

  Therefore, the present invention has been proposed in view of the above-described circumstances, and an object of the present invention is to provide a fuel cell system that can efficiently generate power for each of the external humidification fuel cell and the internal humidification fuel cell. And

  The fuel cell system according to the present invention is provided with a humidifying fluid flow path to which a humidifying fluid is supplied, humidifies the electrolyte membrane with moisture diffused from the humidifying fluid flow path to the reactive gas flow path, and reacts with the reaction gas. An internal humidified fuel cell that performs a power generation reaction by being supplied with a reaction gas from a supply unit; and an external humidification fuel cell that performs a power generation reaction by being supplied with a reaction gas from a reaction gas supply unit. A reaction gas, which is a fuel gas and an oxidant gas, is supplied to the internal humidification fuel cell and the external humidification fuel cell to generate electric power.

  At this time, the reactive gas supply means supplies the fuel gas or oxidant gas to the external humidification fuel cell based on the operating state of the fuel cell system, and the fuel gas or oxidant discharged from the external humidification fuel cell. A state in which gas is supplied to the internal humidification type fuel cell, and a fuel gas or oxidant gas is supplied to the internal humidification type fuel cell, and the fuel gas or oxidant gas discharged from the internal humidification type fuel cell is supplied to the external humidification type fuel cell. The above-mentioned problem is solved by switching the state to be supplied to the battery.

  According to the fuel cell system of the present invention, since the gas supply order between the external humidification fuel cell and the internal humidification fuel cell is switched according to the operating state, the external humidification fuel cell and the internal humidification type are configured. Fuel cell humidification, external humidification type fuel cell and internal humidification type fuel cell can eliminate water clogging and warm up efficiently, and separate humidification for introducing humidification gas into external humidification type fuel cell It is possible to eliminate the need to install a vessel. Accordingly, each of the external humidification fuel cell and the internal humidification fuel cell can be efficiently generated, the system scale can be reduced, and the output density of the generated power with respect to the system scale can be increased. .

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The present invention is applied to a fuel cell system configured as shown in FIG. 1, for example.

  This fuel cell system includes an external humidification fuel cell 1 and an internal humidification fuel cell 2 that generate electric power by receiving supply of a fuel gas and an oxidant gas as reaction gases. In the external humidification fuel cell 1 and the internal humidification fuel cell 2, hydrogen gas as a fuel gas is supplied to the anode, and air as an oxidant gas is supplied to the cathode.

  In the present embodiment, the external humidification fuel cell 1 and the internal humidification fuel cell 2 are solid polymer fuel cells. The electrochemical reaction at the anode (fuel electrode) and cathode (oxidant electrode) of these fuel cells and the reaction as the whole fuel cell are based on the following formulas (1) to (3).

[Anode] H ₂ → 2H ⁺ + 2e ⁻ (1)
[Cathode] 1/2 O ₂ + 2H ⁺ + 2e ⁻ → H ₂ O (2)
[Overall] H ₂ +1/2 O ₂ → H ₂ O (3)
[Configuration of External Humidification Fuel Cell 1 and Internal Humidification Fuel Cell 2]
FIG. 2A is a schematic cross-sectional view showing an example of the internal humidification fuel cell 2, and FIG. 2B is a schematic cross-sectional view showing an example of the external humidification fuel cell 1.

  As shown in FIG. 2A, the cell which is a unit of the internal humidification type fuel cell 2 has an anode electrode catalyst layer 33 and a cathode electrode catalyst layer 34 on both surfaces of an electrolyte membrane 32 using a solid polymer electrolyte membrane. Each includes a membrane electrode assembly (MEA) 31 formed, anode gas diffusion layers 35 and cathode gas diffusion layers 36 disposed on both sides of the MEA 31, water permeable plates 37 and 38, and separators 39 and 40.

  The water permeable plates 37 and 38 are formed, for example, by embedding a porous material 42 having a humidifying function in a large number of through holes provided in a plate-like frame member 41 mainly having a mechanical strength. Pure water passages 53 and 54 are provided between the separator 39 and the water permeable plate 37, and between the separator 40 and the water permeable plate 38, respectively, and pure water as a humidifying fluid is supplied. Pure water permeates into the other surface through the porous material 42 from one surface of the water transmission plates 37 and 38 in contact with the pure water channels 53 and 54. Hydrogen flow paths 51 and air flow paths 52 are provided on the other surfaces of the water permeable plates 37 and 38, respectively, so that pure water permeating from the pure water flow paths 53 and 54 humidifies hydrogen and air, respectively. .

  In the internal humidification type fuel cell 2 shown in FIG. 2A, the pure water channel 53 is adjacent to the hydrogen channel 51 via the water permeable plate 37, and the water channel 52 is connected to the air channel 52. Although the configuration in which the pure water channel 54 is adjacent is shown, the electrolyte membrane 32 may be humidified by humidifying only hydrogen or air. In this case, the water permeable plate and the pure water flow path are provided only on the humidifying side. As a result, in the internal humidification fuel cell 2, one pole provided with the water permeable plate and the pure water flow path becomes a pole where freezing or the like when freezing is likely to occur.

  As shown in FIG. 2B, the cell which is a unit of the external humidification type fuel cell 1 has an anode electrode catalyst layer 33 and a cathode electrode catalyst layer 34 on both surfaces of an electrolyte membrane 32 using a solid polymer electrolyte membrane. Each includes a membrane electrode assembly (MEA) 31 formed, anode gas diffusion layers 35 and cathode gas diffusion layers 36 disposed on both sides of the MEA 31, and separators 39 and 40.

  A hydrogen channel 51 is provided between the separator 39 and the anode gas diffusion layer 35, and hydrogen is supplied. Similarly, an air flow path 52 is provided between the separator 40 and the cathode gas diffusion layer 36 to supply air.

  In the external humidification type fuel cell 1 shown in FIG. 2B, when the humidified gas is supplied to the hydrogen channel 51 and the air channel 52 to humidify the electrolyte membrane 32, the hydrogen channel 51 or In some cases, the humidified gas is supplied to one of the air flow paths 52 to humidify the electrolyte membrane 32.

  In the external humidification type fuel cell 1 having such a configuration, basically, moisture of the humidified gas supplied from the outside and water generated by an electrochemical reaction on the air flow path 52 side are generated depending on the operation state. In addition, the external humidification type fuel cell 1 includes the shape and length of the hydrogen channel 51 and / or the air channel 52 to which the gas to be humidified is supplied, the positional relationship between the hydrogen channel 51 and the air channel 52, and the like. The likelihood of water clogging is determined by the relationship of the flow paths.

  Therefore, when humidified air is introduced into the air flow path 52 of the external humidification fuel cell 1, water clogging easily occurs in the air flow path 52 of the external humidification fuel cell 1, and the external humidification fuel When humidified hydrogen is introduced into the hydrogen channel 51 of the battery 1, not only the air channel 52 but also the hydrogen channel 51 is likely to be clogged.

  Further, as the external humidification type fuel cell 1, there is a battery that cannot specify whether the air flow channel 52 or the hydrogen flow channel 51 is likely to be clogged depending on the operation state. For example, when the external humidification type fuel cell 1 is cold, the hydrogen channel 51 is likely to be clogged, but during normal operation, the air channel 52 is more likely to clog due to the generated water.

[Configuration of fuel cell system]
The fuel cell system includes an air supply system that supplies air to the external humidification fuel cell 1 and the internal humidification fuel cell 2, and a hydrogen supply system that supplies hydrogen gas to the external humidification fuel cell 1 and the internal humidification fuel cell 2 ( And a pure water circulation system (not shown) for circulating pure water in the internal humidification fuel cell 2. The operation of these air supply system, hydrogen supply system, and pure water circulation system is controlled by a control device 21 to be described later, so that the gas supply state to the external humidification fuel cell 1 and the internal humidification fuel cell 2, the internal The pure water supply state to the humidified fuel cell 2 is adjusted.

  As shown in FIG. 1, the air supply system includes an air passage 52 in the external humidification fuel cell 1 and an air passage 52 in the internal humidification fuel cell 2 connected by a gas pipe, and the external humidification fuel cell. The configuration is switchable between a configuration in which 1 is upstream and the internal humidification fuel cell 2 is downstream, and a configuration in which the internal humidification fuel cell 2 is upstream and the external humidification fuel cell 1 is downstream. That is, the air supply system supplies air discharged from the air flow path 52 of the external humidification fuel cell 1 to the air flow path 52 of the internal humidification fuel cell 2 and the air flow of the internal humidification fuel cell 2. It is possible to switch between a configuration in which air discharged from the passage 52 is supplied to the air passage 52 of the external humidification fuel cell 1.

  Specifically, in the air supply system, the filter 11 and the compressor 12 and the first flow path switching valve 13 are connected by a pipe L1, and the first flow path switching valve 13 and the external humidification fuel cell 1 are connected by a pipe L2. The first flow path switching valve 13 and the internal humidification fuel cell 2 are connected by a pipe L3, the external humidification fuel cell 1 and the internal humidification fuel cell 2 are connected by a pipe L4, and the external humidification fuel is connected. The battery 1 and the pressure adjustment valve 19 are connected by a pipe L5 and a pipe L7, the internal humidification type fuel cell 2 and the pressure adjustment valve 19 are connected by a pipe L6 and a pipe L7, and the pressure adjustment valve 19 and the outside air are connected by a pipe L8. Connected with and configured.

  The air supply system is provided in the first flow path switching valve 13 and the actuator 14 provided at the junction of the pipe L1, the pipe L2, and the pipe L3, and the pipe L5 as a configuration for switching the air flow path. The second flow path switching valve 15 and the actuator 16 provided, and the third flow path switching valve 17 and the actuator 18 provided in the pipe L6 are provided. The flow path switching valves 13, 15, and 17 switch the air and hydrogen flow paths when the actuators 14, 16, and 18 are controlled by the control device 21.

  In such a fuel cell system, the pipe L4 that connects the external humidification fuel cell 1 and the internal humidification fuel cell 2 in series is connected to the air flow path 52 of the external humidification fuel cell 1 and the internal humidification fuel cell 2. It is a connected configuration. As a result, the fuel cell system converts the air compressed by the compressor 12 from the first flow path switching valve 13 through the pipe L2 to the external humidification fuel cell 1, the pipe L4, and the internal humidification fuel as shown in FIG. As shown in FIG. 4, the batteries 2 are supplied in the order of the internal humidification fuel cell 2, the pipe L <b> 4, and the external humidification fuel cell 1 through the pipe L <b> 3 from the first flow path switching valve 13.

  At this time, in order to supply air in the order shown in FIG. 3, the control device 21 opens the opening 13b of the first flow path switching valve 13, closes the opening 13c, and switches the second flow path. The actuators 14, 16, and 18 are controlled so that the valve 15 is closed and the third flow path switching valve 17 is opened. Thereby, as shown by the thick line in FIG. 3, the compressor 12 starts the first flow path switching valve 13, the first flow path switching valve 13 starts the external humidification fuel cell 1, and the external humidification fuel cell 1 starts the internal humidification fuel. A flow path through which air flows from the battery 2 and the internal humidification type fuel cell 2 to the pressure regulating valve 19 is formed.

  On the other hand, in order to supply air in the order shown in FIG. 4, the control device 21 opens the opening 13 c of the first flow path switching valve 13 and closes the opening 13 b so as to close the second flow path switching valve. Actuators 14, 16, and 18 are controlled so that 15 is opened and the third flow path switching valve 17 is closed. As a result, as shown by the thick lines in FIG. 4, the compressor 12 starts the first flow path switching valve 13, the first flow path switching valve 13 starts the internal humidification fuel cell 2, and the internal humidification fuel cell 2 starts the external humidification fuel. A flow path for air to flow from the battery 1 and the external humidification fuel cell 1 to the pressure regulating valve 19 is formed.

  The hydrogen supply system includes a hydrogen storage tank that stores hydrogen to be supplied to the external humidification fuel cell 1 and the internal humidification fuel cell 2, and hydrogen supply from the hydrogen storage tank to the external humidification fuel cell 1 and the internal humidification fuel cell 2. A hydrogen pressure regulating valve provided in the piping to be circulated, a circulation flow path for circulating the hydrogen discharged from the external humidification fuel cell 1 and the internal humidification fuel cell 2, a circulation pump, and the like. This hydrogen supply system supplies hydrogen at a hydrogen flow rate and pressure corresponding to the electric power required for the external humidification fuel cell 1 and the internal humidification fuel cell 2 under the control of the control device 21.

  Further, in the hydrogen supply system, similarly to the air supply system shown in FIG. 1, the hydrogen flow path 51 in the external humidification fuel cell 1 and the hydrogen flow path 51 in the internal humidification fuel cell 2 are connected by a gas pipe. It is possible to switch between a configuration in which the external humidification fuel cell 1 is upstream and the internal humidification fuel cell 2 is downstream, and a configuration in which the internal humidification fuel cell 2 is upstream and the external humidification fuel cell 1 is downstream. It may be a simple configuration. That is, the hydrogen supply system supplies the hydrogen discharged from the anode of the external humidification fuel cell 1 to the hydrogen flow path 51 of the internal humidification fuel cell 2 and the hydrogen flow path 51 of the internal humidification fuel cell 2. It is configured to be switched between a configuration in which the discharged hydrogen is supplied to the hydrogen flow path 51 of the external humidification fuel cell 1. In this case, similarly to the air supply system shown in FIG. 1, the hydrogen supply system includes a pipe and a flow path switching valve for connecting the external humidification fuel cell 1 and the internal humidification fuel cell 2, Opening and closing is controlled by the control device 21.

  The pure water circulation system includes a pipe for circulating pure water through the pure water flow paths 53 and 54 in the internal humidification fuel cell 2, a pure water pump, and the like. This pure water circulation system maintains the electrolyte membrane 32 in the internal humidification fuel cell 2 in a wet state by humidifying air or hydrogen supplied to the internal humidification fuel cell 2 by circulating pure water. To do. In addition, air and hydrogen containing moisture by the pure water circulation system are discharged out of the internal humidification fuel cell 2 in a state containing moisture as it is.

  In such a fuel cell system, at least one or both of the air flow path 52 and the hydrogen flow path 51 of the external humidification fuel cell 1 and the internal humidification fuel cell 2 are connected by piping. Thus, the fuel cell system is configured to be able to switch the supply order of air and hydrogen between the external humidification fuel cell 1 and the internal humidification fuel cell 2 in at least one or both of the air flow path 52 and the hydrogen flow path 51. . As described above, whether or not the supply order can be switched between the external humidification fuel cell 1 and the internal humidification fuel cell 2 is determined by the following factors (1) to (3).

(1) Ease of water clogging in the external humidification fuel cell 1 As described with reference to FIG. 2, the air in the external humidification fuel cell 1 depends on the generated water, the humidified gas, the shape of the air flow path 52, and the like. When water clogging is likely to occur in the flow path 52, the air flow path 52 of the external humidification fuel cell 1 and the air flow path 52 of the internal humidification fuel cell 2 are connected, and the air supply system is shown in FIG. Configure as follows. Further, when water clogging is likely to occur in the hydrogen passage 51 of the external humidification fuel cell 1, the hydrogen passage 51 of the external humidification fuel cell 1 and the hydrogen passage 51 of the internal humidification fuel cell 2 are connected. In the hydrogen supply system, the supply order can be switched between the external humidification fuel cell 1 and the internal humidification fuel cell 2.

(2) Humidification electrode side in the internal humidification type fuel cell 2 The pure water channel of the internal humidification type fuel cell 2 is provided in only one of the air channel 52 and the hydrogen channel 51, When the electrolyte membrane 32 is humidified from one side, the external humidification fuel cell 1 and the internal humidification fuel cell 2 are connected on the channel side where the pure water channel is provided.

  That is, when the pure water flow path of the internal humidification fuel cell 2 is provided only on the air flow path 52 side, the air flow path 52 of the external humidification fuel cell 1 and the air flow path of the internal humidification fuel cell 2 52, the supply order can be switched between the external humidification fuel cell 1 and the internal humidification fuel cell 2. When the pure water flow path of the internal humidification fuel cell 2 is provided only on the hydrogen flow path 51 side, the hydrogen flow path 51 of the external humidification fuel cell 1 and the hydrogen flow path of the internal humidification fuel cell 2 51 is connected so that the supply order can be switched between the external humidification fuel cell 1 and the internal humidification fuel cell 2.

(3) When the ease of occurrence of water clogging cannot be specified When the pole where water clogging is likely to occur in the external humidification fuel cell 1 cannot be specified, the external humidification fuel cell 1 and the internal humidification fuel cell 2 The air flow paths 52 are connected to each other and the hydrogen flow paths 51 of the external humidification fuel cell 1 and the internal humidification fuel cell 2 are connected to each other. Thereby, both the air supply system and the hydrogen supply system can switch the supply order of hydrogen and air between the external humidification fuel cell 1 and the internal humidification fuel cell 2.

  As described above, when the piping configuration of the fuel cell system is designed based on the factors (1) to (3), the water clogging of each of the hydrogen flow path 51 and the air flow path 52 of the external humidification fuel cell 1 is performed. When the pole that is most likely to cause water clogging can be identified by experimentation or the like to determine the ease of occurrence, the external humidification fuel cell 1 and the internal humidification are switched at the pole in order to switch the gas supply sequence at the pole. The fuel cell 2 is connected in series. Further, when the pole where water clogging is most likely to occur cannot be specified by experiments or the like, the external humidification fuel cell 1 and the internal humidification fuel cell 2 are connected in series in both the air channel 52 and the hydrogen channel 51. Configured to do.

[Operation of fuel cell system]
Next, an operation when the gas supply order is switched between the external humidification fuel cell 1 and the internal humidification fuel cell 2 by the fuel cell system configured as described above will be described. In the following description of the operation, as shown in FIGS. 1 to 3, a case where the air supply sequence is switched between the external humidification fuel cell 1 and the internal humidification fuel cell 2 in the air supply system will be described. Similarly, the supply order can be switched for the system.

  When switching the air supply order, the control device 21 determines the operating state of the fuel cell system. At this time, the control device 21 generates a surrounding power generation start command for the external humidification fuel cell 1 and the internal humidification fuel cell 2, and the ambient temperature based on the cooling water temperature circulated to the external humidification fuel cell 1 and the internal humidification fuel cell 2. The temperature and the cell voltage of the external humidification fuel cell 1 and the internal humidification fuel cell 2 are detected as the operating state of the fuel cell system.

"On startup"
When the control device 21 detects a power generation start command for the external humidification fuel cell 1 and the internal humidification fuel cell 2 and determines that the fuel cell system is activated, as shown in FIG. Furthermore, the external humidification fuel cell 1 is the upstream, and the internal humidification fuel cell 2 is the downstream. Thereby, the air compressed by the compressor 12 is introduced into the external humidification fuel cell 1 through the first flow path switching valve 13, discharged from the external humidification fuel cell 1, and introduced into the internal humidification fuel cell 2. The pressure is adjusted by the pressure adjusting valve 19.

  At the start of the fuel cell system, when the temperature of the external humidification fuel cell 1 is as low as room temperature and moisture is introduced, moisture is condensed in the external humidification fuel cell 1 to cause clogging. However, by introducing air that is not humidified to the external humidification type fuel cell 1, occurrence of water clogging in the external humidification type fuel cell 1 is avoided. In addition, even if it is a case where dry air is introduce | transduced in the external humidification fuel cell 1 immediately after starting, the tolerance of the external humidification fuel cell 1 is not deteriorated.

  Accordingly, when the fuel cell system is started, the external humidification fuel cell 1 and the internal humidification fuel cell 2 are avoided while the external humidification fuel cell 1 is prevented from being clogged by setting the external humidification fuel cell 1 upstream. By this, stable power generation can be performed.

  Further, the power generation by the external humidification fuel cell 1 and the internal humidification fuel cell 2 is stopped, and the cooling water of the external humidification fuel cell 1 and the internal humidification fuel cell 2 is again about 60 ° C. to 70 ° C. Even during the hot start to start, it is considered that water clogging is likely to occur in the external humidification fuel cell 1 as compared to during normal operation. Therefore, the external humidification fuel cell 1 is located upstream and internal humidification fuel. It is desirable to place the battery 2 downstream.

"When cold"
When the control device 21 determines that the temperature of at least one of the external humidification fuel cell 1 and the internal humidification fuel cell 2 is, for example, 50 ° C. or less during cold-cooling, as shown in FIG. The humidified fuel cell 1 is the upstream, and the internal humidified fuel cell 2 is the downstream.

  When the fuel cell system is cold, if the temperature of the external humidification fuel cell 1 is low and humidified air is introduced, moisture is condensed in the external humidification fuel cell 1 and water clogging is likely to occur. However, by introducing air that is not humidified to the external humidification fuel cell 1, occurrence of water clogging in the external humidification fuel cell 1 is avoided. Even when dry air is introduced into the external humidification fuel cell 1, the durability of the external humidification fuel cell 1 is not deteriorated.

  Accordingly, when the fuel cell system is cold, the external humidification fuel cell 1 and the internal humidification fuel cell 2 are avoided while preventing the external humidification fuel cell 1 from being clogged by setting the external humidification fuel cell 1 upstream. By this, stable power generation can be performed.

"When starting below freezing"
When the control device 21 determines that the temperature of the cooling water flowing in the external humidification fuel cell 1 and the internal humidification fuel cell 2 is to be started under a condition corresponding to, for example, below 5 ° C., as shown in FIG. The external humidification fuel cell 1 is the upstream and the internal humidification fuel cell 2 is the downstream.

  At the time of starting below the freezing point of this fuel cell system, there is a possibility that the pure water remaining in the pure water flow path of the internal humidification type fuel cell 2 is frozen, and when the pure water is frozen, the electrolyte membrane Since it is difficult to bring 32 into a wet state, power generation by the internal humidification type fuel cell 2 becomes difficult. On the other hand, the fuel cell system first starts power generation of the external humidification fuel cell 1 and transmits heat generated by the external humidification fuel cell 1 to the internal humidification fuel cell 2.

  At this time, the fuel cell system warms up the internal humidification type fuel cell 2 by introducing the air discharged from the external humidification type fuel cell 1 into the internal humidification type fuel cell 2. Alternatively, the internal humidified fuel cell 2 may be warmed up by introducing the cooling water that has passed through the external humidified fuel cell 1 into the internal humidified fuel cell 2. As a result, the internal humidification fuel cell 2 is warmed up by transferring heat generated by the external humidification fuel cell 1 to the internal humidification fuel cell 2.

  Therefore, when the fuel cell system is started below freezing, the external humidifying fuel cell 1 is set upstream, the internal humidifying fuel cell 2 is set downstream, and the external humidifying fuel cell 1 is first generated to generate power. However, power generation can be performed quickly, and by generating heat from the external humidification fuel cell 1 to the internal humidification fuel cell 2, power generation by the internal humidification fuel cell 2 can be started in a short time.

"When a water clog occurs"
The control device 21 reads a cell voltage from a cell voltage sensor that detects the voltage of the fuel cell constituting the external humidification fuel cell 1 and acquires a plurality of cell voltages of the external humidification fuel cell 1. And the control apparatus 21 calculates | requires the average cell voltage which averaged the several cell voltage, and when the cell voltage which fell more than the predetermined ratio with respect to the said average cell voltage is detected, it determines with water clogging having generate | occur | produced.

  Accordingly, as shown in FIG. 3, the control device 21 sets the external humidification fuel cell 1 to the upstream and the internal humidification fuel cell 2 to the downstream. As a result, the clogged water is eliminated by preferentially introducing the dry air into the external humidified fuel cell 1 where the clogged water has occurred. As described above, even when water clogging occurs, the external humidification fuel cell 1 is immediately set upstream so that the reduction in power generation efficiency due to water clogging can be eliminated immediately.

"During normal operation"
As shown in FIG. 4, the control device 21 performs internal humidification as shown in FIG. 4 during normal power generation when the temperatures of both the external humidification fuel cell 1 and the internal humidification fuel cell 2 are, for example, 50 ° C. or higher. The fuel cell 2 is the upstream and the external humidification fuel cell 1 is the downstream. That is, when it is determined that the warm-up is completed in a state where the external humidification fuel cell 1 is set upstream and the internal humidification fuel cell 2 is set downstream at the start-up or sub-freezing start-up described above, FIG. As shown, the internal humidification fuel cell 2 is switched upstream and the external humidification fuel cell 1 is switched downstream.

  Thus, in the fuel cell system, the air humidified by the internal humidification fuel cell 2 is introduced into the external humidification fuel cell 1, and the electrolyte membrane 32 of the external humidification fuel cell 1 is maintained in a wet state. Can do. Thereby, in the fuel cell system, the electrolyte membrane 32 can be humidified without using a separate humidifier for humidifying the air introduced into the external humidification fuel cell 1.

  Further, the operation of the fuel cell system with respect to each operation state described above has been described only on the air flow path 52 side of the external humidification fuel cell 1 and the internal humidification fuel cell 2, but also on the hydrogen flow path 51 side. Similarly to the 52 side, the supply order may be switched according to the operating state. Further, in the above-described “start-up”, “cool-down”, and “below freezing start-up”, the internal humidification type fuel cell 2 is more likely to be clogged than the external humidification type fuel cell 1. Alternatively, the internal humidification fuel cell 2 may be upstream and the external humidification fuel cell 1 may be downstream, as opposed to the operation of setting the external humidification fuel cell 1 upstream. Further, even when “water clogging occurs”, not only the external humidification fuel cell 1 but also the internal humidification fuel cell 2 is judged whether water clogging has occurred, and the external humidification fuel cell 1 and the internal humidification type fuel cell 1. Of the fuel cells 2, the fuel cell in which water clogging has occurred may be upstream.

[Other configurations of fuel cell system]
Next, another configuration of the fuel cell system will be described.

  The fuel cell system to which the present invention is applied may be configured as shown in FIG. 5 or FIG. 6 as a configuration for switching the supply order of air and hydrogen between the external humidification fuel cell 1 and the internal humidification fuel cell 2. good.

  In the fuel cell system shown in FIG. 5, the compressor 12 and the three-way valve 61 are connected via a pipe L1, the external humidification fuel cell 1 is connected to the three-way valve 61 via a pipe L2, and the pipe L3 is connected. Then, the internal humidification fuel cell 2 is connected, and the external humidification fuel cell 1 and the internal humidification fuel cell 2 are connected in series by a pipe L4. In this fuel cell system, a three-way valve 62 is provided at the junction of the pipe L5 and the pipe L6 instead of the second flow path switching valve 15 and the third flow path switching valve 17 in FIG. A pressure regulating valve 63 is provided on the discharge side.

  In such a fuel cell system, when the external humidification type fuel cell 1 is upstream and the internal humidification type fuel cell 2 is downstream as shown in FIG. 3, the opening on the pipe L6 side of the three-way valve 62 is opened. At the same time, the piping L5 side opening of the three-way valve 62 is closed. As shown in FIG. 4, when the internal humidification fuel cell 2 is set upstream and the external humidification fuel cell 1 is set downstream, the opening of the three-way valve 62 on the pipe L6 side is closed, and the three-way valve 62 Pipe L5 side opening is made into an open state.

  The fuel cell system shown in FIG. 6 is provided with an opening / closing valve 71 in the pipe L2 and an opening / closing valve 72 in the pipe L3 instead of the first passage switching valve 13 in FIG. An on-off valve 73 and an on-off valve 74 corresponding to the three flow path switching valve 17 and a pressure adjusting valve 75 corresponding to the pressure adjusting valve 19 are provided.

  In such a fuel cell system, as shown in FIG. 3, when the external humidification fuel cell 1 is set upstream and the internal humidification fuel cell 2 is set downstream, the on-off valve 71 is opened and the on-off valve 72 is opened. Is closed. As shown in FIG. 4, when the internal humidification fuel cell 2 is set upstream and the external humidification fuel cell 1 is set downstream, the open / close valve 72 is closed and the open / close valve 71 is opened.

[Effect of the embodiment]
As described above in detail, the fuel cell system to which the present invention is applied is configured to switch the gas supply order between the external humidification fuel cell 1 and the internal humidification fuel cell 2 in accordance with the operating state. Therefore, the humidification of the electrolyte membrane 32 of the external humidification fuel cell 1 and the internal humidification fuel cell 2, the elimination of water clogging and the warm-up of the external humidification fuel cell 1 and the internal humidification fuel cell 2 can be performed efficiently. In addition, it is possible to eliminate the need to install a separate humidifier for introducing the humidified gas into the external humidified fuel cell 1. Therefore, each of the external humidification fuel cell 1 and the internal humidification fuel cell 2 can efficiently generate power, the system scale can be reduced, and the output density of the generated power with respect to the system scale can be increased. Can do.

  Further, according to this fuel cell system, when the air flowing in the air flow path 52 out of the hydrogen flow path 51 and the air flow path 52 of the internal humidification fuel cell 2 is humidified, the internal humidification fuel cell 2 is concerned. A state in which the external humidification fuel cell 1 is upstream and the internal humidification fuel cell 2 is downstream, and the internal humidification type Since the fuel cell 2 is switched to the upstream state and the external humidified fuel cell 1 is switched to the downstream state, the humidified state of the external humidified fuel cell 1 at the air electrode during normal operation can be kept good.

  Furthermore, according to this fuel cell system, when the hydrogen flowing in the hydrogen flow channel 51 out of the hydrogen flow channel 51 and the air flow channel 52 of the internal humidification fuel cell 2 is humidified, the internal humidification fuel cell 2 is concerned. The hydrogen flow path 51 of the external humidification fuel cell 1 and the hydrogen flow path 51 of the external humidification fuel cell 1 are connected in series, with the external humidification fuel cell 1 being upstream and the internal humidification fuel cell 2 being downstream; Since the fuel cell 2 is switched to the upstream state and the external humidified fuel cell 1 is switched to the downstream state, the humidified state of the externally humidified fuel cell 1 at the hydrogen electrode during normal operation can be kept good.

  Furthermore, according to this fuel cell system, when the hydrogen and air flowing in the hydrogen flow path 51 and the air flow path 52 of the internal humidification type fuel cell 2 are humidified, the hydrogen flow path of the internal humidification type fuel cell 2 is concerned. 51 and the air flow path 52 and the hydrogen flow path 51 and the air flow path 52 of the external humidification fuel cell 1 are connected in series, with the external humidification fuel cell 1 being upstream and the internal humidification fuel cell 2 being downstream. Switching between the state and the state where the internal humidification fuel cell 2 is upstream and the external humidification fuel cell 1 is downstream can maintain the humidification state of the external humidification fuel cell 1 well.

  Furthermore, according to this fuel cell system, the external humidification fuel cell 1 and the internal humidification fuel cell on the side where the water clogging is likely to occur in the hydrogen flow path 51 and the air flow path 52 of the external humidification fuel cell 1. 2 are connected in series, with the external humidification fuel cell 1 being upstream and the internal humidification fuel cell 2 being downstream, and the internal humidification fuel cell 2 being upstream and the external humidification fuel cell 1 being downstream. Since switching according to the state, clogging of the external humidified fuel cell 1 can be reliably suppressed.

  The above-described embodiment is an example of the present invention. For this reason, the present invention is not limited to the above-described embodiment, and various modifications can be made depending on the design and the like as long as the technical idea according to the present invention is not deviated from this embodiment. Of course, it is possible to change.

  That is, in the fuel cell system described above, the configuration including one external humidification fuel cell 1 and one internal humidification fuel cell 2 has been described. However, the present invention is not limited to this, and the gas supply sequence as described above is controlled. Thus, even when a plurality of external humidification fuel cells 1 and internal humidification fuel cells 2 are provided, the same effect can be obtained.

It is a block diagram which shows the structure of the fuel cell system to which this invention is applied. (A) Schematic sectional view showing an example of an internal humidification fuel cell, (b) Schematic sectional view showing an example of an external humidification fuel cell. In the fuel cell system to which the present invention is applied, it is a block diagram for explaining the operation when the external humidification fuel cell is upstream and the internal humidification fuel cell is downstream. In the fuel cell system to which the present invention is applied, it is a block diagram for explaining the operation when the internal humidification type fuel cell is upstream and the external humidification type fuel cell is downstream. It is a block diagram which shows the other structure of the fuel cell system to which this invention is applied. It is a block diagram which shows the further another structure of the fuel cell system to which this invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 External humidification type fuel cell 2 Internal humidification type fuel cell 11 Filter 12 Compressor 13 First flow path switching valve 14, 16, 18 Actuator 15 Second flow path switching valve 17 Third flow path switching valve 19, 63, 75 Pressure adjustment Valve 21 Control device 31 MEA
32 Electrolyte membrane 33 Anode electrode catalyst layer 34 Cathode electrode catalyst layer 35 Anode gas diffusion layer 36 Cathode gas diffusion layer 37, 38 Water permeable plate 39, 40 Separator 41 Frame material 42 Porous material 51 Hydrogen flow channel 52 Air flow channel 53 54 Pure water flow path 61, 62 Three-way valve 71, 72, 73, 74 On-off valve

Claims (10)

A reaction gas supply means for supplying a reaction gas which is a fuel gas and an oxidant gas;
A humidifying fluid flow path to which a humidifying fluid is supplied is provided, and the electrolyte membrane is humidified by moisture diffused from the humidifying fluid flow path to the reactive gas flow path, and the reactive gas is supplied from the reactive gas supply means. An internal humidified fuel cell that performs a power generation reaction,
An external humidified fuel cell that performs a power generation reaction by supplying a reactive gas from the reactive gas supply means;
The reaction gas supply means supplies a fuel gas or an oxidant gas to the external humidification fuel cell based on an operating state of the fuel cell system, and a fuel gas or an oxidant gas discharged from the external humidification fuel cell. Is supplied to the internal humidification type fuel cell, fuel gas or oxidant gas is supplied to the internal humidification type fuel cell, and the fuel gas or oxidant gas discharged from the internal humidification type fuel cell is supplied to the external humidification type fuel cell. A fuel cell system, wherein the state to be supplied to the fuel cell is switched. The internal humidification type fuel cell is configured to humidify the fuel gas supplied from the reaction gas supply means,
The reactive gas supply means supplies fuel gas to the external humidification fuel cell and supplies the fuel gas discharged from the external humidification fuel cell to the internal humidification fuel cell; and the internal humidification fuel 2. The fuel cell system according to claim 1, wherein a fuel gas is supplied to the battery, and a state in which the fuel gas discharged from the internal humidification fuel cell is supplied to the external humidification fuel cell is switched. The internal humidification type fuel cell is configured to humidify the oxidant gas supplied from the reaction gas supply means,
The reactive gas supply means supplies an oxidant gas to the external humidification fuel cell, supplies the oxidant gas discharged from the external humidification fuel cell to the internal humidification fuel cell, and the internal humidification fuel cell. 2. The fuel according to claim 1, wherein an oxidant gas is supplied to the fuel cell and the state in which the oxidant gas discharged from the internal humidification fuel cell is supplied to the external humidification fuel cell is switched. Battery system. The internal humidification type fuel cell is configured to humidify the fuel gas and the oxidant gas supplied from the reaction gas supply means,
The reactive gas supply means supplies fuel gas and oxidant gas to the external humidification fuel cell, and supplies fuel gas and oxidant gas discharged from the external humidification fuel cell to the internal humidification fuel cell. Switching between a state and a state in which a fuel gas and an oxidant gas are supplied to the internal humidification fuel cell and a fuel gas and an oxidant gas discharged from the internal humidification fuel cell are supplied to the external humidification fuel cell The fuel cell system according to claim 1. The external humidification type fuel cell includes a fuel gas channel through which a fuel gas supplied from the reaction gas supply unit flows, and an oxidant gas channel through which an oxidant gas supplied from the reaction gas supply unit flows. Connecting at least one flow path where water clogging is likely to occur and the internal humidified fuel cell;
The reaction gas supply means supplies a reaction gas to the external humidification fuel cell and supplies the reaction gas discharged from the external humidification fuel cell to the internal humidification fuel cell; and the internal humidification fuel 2. The fuel cell system according to claim 1, wherein a state in which a reaction gas is supplied to the battery and a reaction gas discharged from the internal humidification fuel cell is supplied to the external humidification fuel cell is switched.   The reactive gas supply means supplies a reactive gas to the external humidified fuel cell and starts supplying the reactive gas discharged from the external humidified fuel cell to the internal humidified fuel cell when the fuel cell system is activated. The fuel cell system according to any one of claims 1 to 5, wherein:   The reaction gas supply means supplies the reaction gas to the external humidification fuel cell and supplies the reaction gas discharged from the external humidification fuel cell to the internal humidification fuel cell when the fuel cell system is cold. The fuel cell system according to any one of claims 1 to 5, wherein:   The reactive gas supply means supplies a reactive gas to the external humidified fuel cell and supplies a reactive gas discharged from the external humidified fuel cell to the internal humidified fuel cell when the fuel cell system is started below freezing point. The fuel cell system according to any one of claims 1 to 5, wherein the fuel cell system is in a state.   When the reactive gas supply means determines that water clogging has occurred in the external humidified fuel cell, the reactive gas supply means supplies the reactive gas to the external humidified fuel cell and discharges the reactive gas discharged from the external humidified fuel cell. The fuel cell system according to any one of claims 1 to 5, wherein the fuel cell system is in a state of being supplied to the internal humidified fuel cell. The reactive gas supply means supplies a reactive gas to the internal humidified fuel cell and supplies the internal humidified fuel cell when at least one of the external humidified fuel cell and the internal humidified fuel cell reaches a predetermined temperature or higher. 6. The fuel cell system according to claim 1, wherein the reaction gas discharged from the fuel cell is supplied to the external humidification fuel cell.

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