JP5348882B2 - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent or suppress degradation of power generation performance accompanying an increase of a temperature of a fuel cell. <P>SOLUTION: The fuel cell system includes a fuel cell 50 formed by laminating a plurality of unit cells, and a controller 29 for detecting a temperature change of the fuel cell 50 from a temperature state detected by a temperature sensor 28 and conducting predetermined control for suppressing an pressure loss increase on a fuel electrode side in response to a temperature increase of the fuel cell 50. The controller 29 conducts at least one control out of (1) increasing an oxide gas supply flow rate from an oxide gas supply device 20, (2) reducing a fuel gas supply flow rate from a fuel gas supply device 19, (3) reducing an outlet pressure of offgas of oxide gas by regulating a pressure regulating valve 24, and (4) increasing an output pressure of offgas of fuel gas by regulating a pressure regulating valve 23. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a fuel cell system including a cell stack formed by stacking a plurality of single cells.

  The outline of the structure of the fuel cell which comprises a fuel cell system is demonstrated. FIG. 5 is a diagram showing an example of a general configuration of a general fuel cell. Note that in FIG. 5, some of the configurations are omitted or simplified.

  In FIG. 5, the fuel cell 50 is configured such that desired power generation performance can be obtained by stacking a plurality of single cells 11 having predetermined battery performance. In general, the fuel cell 50 is sandwiched between current collecting plates 12 and 13 at the stacking ends of the stacked unit cells 11, and further sandwiched between the insulating plates 14 and 15 and the end plates 16 and 17 in order from the outside. For example, the whole is pressed and held in the stacking direction by a method such as fastening with a bolt or the like (not shown). Thus, since the fuel cell 50 has a configuration in which a plurality of single cells 11 are stacked, the fuel cell 50 may be referred to as a cell stack in order to be distinguished from the single cells 11.

  In FIG. 5, a refrigerant supply manifold 18a and a refrigerant discharge manifold 18b penetrating each single cell 11 are formed independently. Further, a cell refrigerant flow path 10 is formed between each single cell 11, and the refrigerant supply manifold 18a and the refrigerant discharge manifold 18b are communicated with each other. The cooling medium (refrigerant) introduced from the outside of the fuel cell 50 as shown by the arrow 30 branches as shown by the arrow 30a and is distributed to each cell refrigerant flow path 10 to exchange heat with each single cell 11. . The used cooling medium having undergone heat exchange in each single cell 11 flows into and merges with the refrigerant discharge manifold 18b as indicated by an arrow 31a, and is discharged to the outside of the fuel cell 50 as indicated by an arrow 31.

  Next, the configuration of the main part of the single cell 11 shown in FIG. 5 will be described. As illustrated in FIG. 6, an anode catalyst layer 2 (also referred to as an anode electrode or a fuel electrode) is provided on one surface of the electrolyte membrane 1, and a cathode catalyst layer 3 (also referred to as a cathode electrode or an oxidation electrode) is provided on the other surface. Are provided so as to face each other with the electrolyte membrane 1 interposed therebetween, and further, an anode diffusion layer 4 is provided outside the anode catalyst layer 2, and a cathode diffusion layer 5 is provided outside the cathode catalyst layer 3, respectively. MEA) is configured. An anode separator 6 having a fuel gas flow path 8 and a cell refrigerant flow path 10 formed on the outside of the anode diffusion layer 4, and an oxidizing gas flow path 9 and a cell refrigerant flow on the outside of the cathode diffusion layer 5. The cathode-side separator 7 in which the passage 10 is formed is integrated by, for example, adhesion or the like, and the single cell 11 is formed.

  A fuel gas containing at least hydrogen such as reformed gas or hydrogen gas is supplied to the anode catalyst layer 2 shown in FIG. 6, and an oxidizing gas containing at least oxygen such as air or oxygen gas is supplied to the cathode catalyst layer 3 respectively. Generate electricity. By stacking a plurality of the single cells 11, a fuel cell having a desired power generation performance as shown in FIG. 5 is formed. Since such a fuel cell usually generates heat associated with a chemical reaction during power generation, the aforementioned cooling medium is circulated or circulated in order to prevent overheating of the fuel cell, and a suitable temperature of, for example, about 60 ° C. to 100 ° C. It is controlled to be in range.

  By the way, in FIG. 5, the temperature distribution with respect to the single cell lamination direction at the time of power generation in the fuel cell 50 is not necessarily uniform. That is, in the single cell 11 positioned in the vicinity of the stacked end portions 11a and 11c and the vicinity of the stacked end portions 11a and 11c, the center of the stack is formed by heat radiation from the current collector plates 12 and 13 made of metal or the like and the end plates 16 and 17 in contact with the outside. The temperature may be lower than that of the single cell 11 of the portion 11g. At this time, compared with the laminated central portion 11g, the power generation performance may not be sufficiently exhibited in the laminated end portions 11a and 11c and the vicinity thereof, and the cell voltage may be lowered.

  For example, Patent Documents 1 to 4 describe a technique for suppressing a voltage drop at a specific portion of the cell stack, such as a stacked end.

  Patent Document 1 describes a technique for heating the end cells by circulating the cooling water after circulating in the fuel cell stack in the end plate.

  Patent Documents 2 and 3 describe techniques for adjusting the amount of water in the electrode part by controlling the pressure difference between the anode gas and the cathode gas.

  Patent Document 4 describes a technique for increasing the amount of heat generated in the end cell to prevent freezing in the end cell during low temperature startup.

JP 2001-68141 A JP 2000-340241 A JP 2004-127914 A JP 2005-85530 A

  In FIG. 5, when the temperature gradient in the stacked central portion 11g and the stacked end portions 11a and 11c of the single cell 11 in the fuel cell 50 increases, the temperature difference between the single cells 11 at the stacked central portion and the stacked end portions is not limited to one. There may be a case where the temperature difference between the anode side and the cathode side in the single cell 11 cannot be ignored. For example, in FIG. 5, the temperature on the anode side located on the outer side of the fuel cell 50, that is, on the end plate 17 side, may be lower than the temperature on the cathode side in the minus-side stacked end unit cell 11a and its vicinity. At this time, based on the temperature difference between the anode side and the cathode side, a difference in water vapor partial pressure occurs between the gas flow channels facing each other across the electrolyte membrane. Based on this partial pressure difference, the electrolyte membrane is In some cases, water vapor permeates to the anode side, and the moisture content on the anode side increases.

  The anode side generally serves as a driving source for discharging condensed water, and the gas energy of the flowing fuel gas is smaller than the gas energy of the oxidizing gas flowing through the cathode side. For this reason, when the amount of moisture on the anode side increases and the remaining moisture condenses in the anode side flow path as liquid water, the drainage may stagnate and increase the pressure loss in the flow path. For this reason, in the minus-side stacked end unit cell 11a and in the vicinity thereof, there is a possibility that the voltage decreases due to the decrease in the fuel gas supply amount on the anode side, and further the deterioration of MEA may be promoted.

  The present invention relates to a fuel cell system and a control method therefor that can prevent or suppress a decrease in power generation performance associated with cell stack temperature rise.

  The configuration of the present invention is as follows.

  (1) A cell stack formed by stacking a plurality of unit cells each having a fuel electrode and an oxidation electrode facing each other with an electrolyte membrane interposed therebetween, fuel gas supply means for supplying fuel gas to the cell stack, and the fuel gas A fuel gas introduction path for introducing the fuel gas from the supply means into the cell stack, and the fuel gas off-gas of the fuel gas introduced into the cell stack along with the circulation of the fuel electrode. A fuel gas discharge path for discharging to the outside, an oxidizing gas supply means for supplying an oxidizing gas to the cell stack, and an oxidizing gas introduction path for introducing the oxidizing gas into the cell stack from the oxidizing gas supply means And off-gas of the oxidizing gas that is introduced into the cell stack and flows along with the flow of the oxidizing electrode to the outside of the cell stack. An oxidizing gas discharge path, a temperature state detecting means for detecting a temperature state of the cell stack, and a temperature increase of the cell stack detected based on the temperature state detected by the temperature state detecting means. And a controller that controls to suppress an increase in pressure loss on the fuel electrode side.

  (2) The fuel cell system according to (1), wherein the controller performs control to increase an oxidant gas supply flow rate from the oxidant gas supply unit in response to a temperature rise of the cell stack. .

  (3) In the fuel cell system according to the above (1) or (2), the controller performs control to decrease the flow rate of fuel gas supplied from the fuel gas supply means in accordance with the temperature rise of the cell stack. , Fuel cell system.

  (4) In the fuel cell system according to any one of (1) to (3) above, an oxidizing electrode side discharge pressure capable of adjusting an oxidizing gas passage outlet pressure of the oxidizing gas off-gas from the cell stack. A fuel cell system, further comprising an adjustment unit, wherein the controller performs control to reduce an off-gas outlet pressure of the oxidizing gas in response to a temperature rise of the cell stack.

  (5) In the fuel cell system according to any one of (1) to (4), a fuel electrode side discharge pressure capable of adjusting a fuel gas passage outlet pressure of the off gas of the fuel gas from the cell stack. The fuel cell system, further comprising an adjusting unit, wherein the controller performs control to increase an outlet pressure of the off-gas of the fuel gas in accordance with a temperature rise of the cell stack.

  (6) In the fuel cell system according to any one of (1) to (5), a cooling medium used for heat exchange with the single cell is introduced into the cell stack, A temperature sensor capable of detecting a cooling medium temperature in the vicinity of an outlet from the cell stack, further comprising a refrigerant flow path for discharging the cooling medium heat-exchanged with the single cell to the outside of the cell stack; Including a fuel cell system.

  (7) A cell stack control method in which a plurality of single cells each having a fuel electrode and an oxidation electrode facing each other with an electrolyte membrane interposed therebetween are stacked, and a fuel gas introduction step for introducing a fuel gas into the cell stack A fuel gas discharging step of discharging the fuel gas introduced into the cell stack to the outside of the cell stack, and an oxidizing gas inside the cell stack. An oxidant gas introduction step for introducing oxidant gas, an oxidant gas discharge step for discharging an oxidant gas off-gas accompanying the circulation of the oxidant electrode to the outside of the cell stack of the oxidant gas introduced into the cell stack, and the single cell A temperature rise sensing step for sensing a temperature rise of the fuel cell, and a step of suppressing an increase in pressure loss on the fuel electrode side in response to the sensed temperature rise of the single cell.

  (8) The control method according to (7), wherein the step of suppressing an increase in pressure loss on the fuel electrode side includes a step of increasing an introduction amount of the oxidizing gas.

  (9) The control method according to (7) or (8), wherein the step of suppressing an increase in pressure loss on the fuel electrode side includes a step of reducing the amount of fuel gas introduced.

  (10) In the control method according to any one of (7) to (9), the step of suppressing an increase in pressure loss on the fuel electrode side includes a discharge pressure of the oxidizing gas off-gas from the cell stack. A control method including a step of reducing the amount.

  (11) In the control method according to any one of (7) to (10), the step of suppressing an increase in pressure loss on the fuel electrode side includes a discharge pressure of the off-gas of the fuel gas from the cell stack. A control method including a step of increasing the value.

  (12) In the control method according to any one of (7) to (11) above, a cooling medium to be used for heat exchange with the single cell is introduced into the cell stack, and the single unit A refrigerant circulation step for discharging the cooling medium heat-exchanged with the cell to the outside of the cell stack, wherein the temperature rising detection step detects the temperature of the cooling medium discharged to the outside of the cell stack; A control method including a process.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to prevent or suppress the fall of the power generation performance accompanying a cell stack temperature rising.

  Embodiments of the present invention will be described with reference to the drawings. In addition, in each drawing demonstrated below, the same code | symbol is attached | subjected about the thing similar to the structure shown in FIG.5, 6, and the description is abbreviate | omitted.

  FIG. 1 is a schematic diagram showing an outline of a configuration of a fuel cell system according to an embodiment of the present invention. A fuel cell system 100 shown in FIG. 1 supplies a fuel cell 50 (cell stack) and a fuel gas containing at least hydrogen to the fuel electrode side (anode side) of the fuel cell 50 via a fuel gas introduction path 19a. And an oxidizing gas for supplying an oxidizing gas containing at least oxygen to the oxidizing electrode side (cathode side) of the fuel cell 50 via the oxidizing gas introduction path 20a. A supply device 20 (oxidizing gas supply means) and a controller 29 that monitors the operation state of the fuel cell 50 and performs predetermined operation control as necessary are provided.

  In FIG. 1, for example, a fuel gas, such as a reformer or a hydrogen cylinder, in which the supply flow rate or flow velocity from the fuel gas supply device 19 is appropriately adjusted is adjusted to a suitable moisture amount through a humidifier 21 as necessary. And introduced into the fuel cell 50. The fuel gas introduced into the fuel cell 50 reaches the anode catalyst layer 2 via the anode diffusion layer 4 from the fuel gas flow path 8 of each single cell 11 shown in FIG. 6, and hydrogen contained in the fuel gas. Is subjected to a battery reaction through the electrolyte membrane 1. Thereafter, surplus hydrogen gas, water vapor, and possibly off-gas of the fuel gas containing carbon dioxide and the like are discharged from the fuel gas discharge path 19b by a pressure adjusting valve 23 (discharge pressure adjusting means) as required. The gas pressure is adjusted to the gas pressure (in the embodiment, the exhaust gas pressure of the off-gas of the fuel gas can be measured using the pressure sensor 25), and is discharged to the outside of the fuel cell 50.

  On the other hand, in FIG. 1, for example, an oxidizing gas, such as a blower, an air pump, an air cylinder, or an oxygen cylinder, whose supply flow rate or flow velocity from the oxidizing gas supply device 20 is appropriately adjusted is appropriately transmitted through a humidifier 22 as necessary. The humidity is adjusted to the amount of water and introduced into the fuel cell 50. The oxidizing gas introduced into the fuel cell 50 reaches the cathode catalyst layer 3 via the cathode diffusion layer 5 from the oxidizing gas flow path 9 of each single cell 11 shown in FIG. 6, and oxygen contained in the oxidizing gas. Is subjected to an electrode reaction through the electrolyte membrane 1. Thereafter, surplus oxygen gas, water vapor, and, in some cases, nitrogen gas or other oxidizing gas off-gas is discharged from the oxidizing gas discharge path 20b as required by the pressure adjusting valve 24 (discharge pressure adjusting means). The gas pressure (in the embodiment, the exhaust gas pressure of the oxidizing gas off-gas can be measured using the pressure sensor 26) is discharged to the outside of the fuel cell 50.

  In addition, in FIG. 1, a cooling medium circulation device 27 including a circulation pump and a heat radiating unit (not shown) may be provided. A cooling medium such as water or ethylene glycol used for heat exchange with the single cell is introduced into the fuel cell 50 through the refrigerant supply path 27a and the refrigerant supply manifold 18a shown in FIG. The heat exchange with the single cell 11 is performed. The cooling medium heated by heat exchange with the single cell 11 passes through the refrigerant discharge manifold 18b shown in FIG. 5 and is discharged to the outside of the fuel cell 50 through the refrigerant discharge path 27b shown in FIG. After being radiated and regenerated in a heat radiating section (not shown), it is used again as a cooling medium. Hereinafter, a series of paths including the refrigerant introduction path 27a and the refrigerant discharge path 27b may be collectively referred to as a refrigerant distribution path. In FIG. 1, the circulation of the cooling medium is shown as a circulation system. However, in other embodiments, for example, tap water branched from the water supply is used as the cooling medium, and the fuel cell is continuously circulated without being circulated. It is also possible to use 50 cooling.

  Furthermore, the fuel cell system 100 shown in FIG. 1 includes a temperature sensor 28 (temperature state detection means) that detects the temperature state of the fuel cell 50. In the embodiment, the temperature sensor 28 detects a temperature state at one or more fixed points in order to determine, for example, whether the fuel cell 50 is in a temperature rising state or has reached a steady state. Specifically, as shown in FIG. 1, the coolant discharge path 27b is provided near the outlet from the fuel cell 50, and the temperature of the coolant immediately after being discharged from the inside of the fuel cell 50 is defined as the temperature of the fuel cell 50. However, the present invention is not limited to this as long as it accurately reflects the temperature state of the fuel cell 50. For example, the structure for detecting the temperature of the insulating plate 15 and the end plate 17 shown in FIG. Various configurations, such as a configuration for directly measuring the temperature of, can be employed.

  In FIG. 1, the controller 29 detects the temperature state of the fuel cell 50 detected by the temperature sensor 28, the discharge pressure of oxidizing gas and / or fuel gas off-gas detected by the pressure sensors 25 and 26, and the operation of the fuel cell 50. Based on information such as the state, the supply amount of the fuel gas supplied by the fuel gas supply device 19 and / or the supply amount of the oxidizing gas supplied by the oxidizing gas supply device 20 and the pressure adjusting valves 23 and 24 are adjusted. The fuel gas and / or the oxidizing gas off-gas discharge pressure (back pressure) is controllable.

  In such a fuel cell system, the temperature of the fuel cell 50 when the operation is stopped is maintained at the same level as the outside air temperature or the ambient temperature of the stack case in which the cell stack is accommodated. On the other hand, when the fuel cell 50 is started, the temperature gradually increases and reaches, for example, a specified temperature (for example, 80 ° C.) at which steady operation is performed over several minutes to several tens of minutes.

  FIG. 2 is a graph comparing the states of the single cells in the stacking direction during the steady operation of the fuel cell 50 shown in FIG. In FIG. 2, the horizontal axis indicates the stacking direction of the single cells. The direction of the horizontal axis corresponds to the shape of the fuel cell 50 shown in FIG. 5, the left end is the stacked end on the cathode current collector 12 side (also referred to as the plus side), and the right end is the anode current collector. Laminated end portions on the plate 13 side (also referred to as a minus side) are shown.

  FIG. 2A is a graph showing an outline of the temperature distribution in the stacking direction of the single cells during the steady operation of the fuel cell 50. In FIG. 2A, the vertical axis indicates the temperature of the cooling medium (cooling water is used in the present embodiment) flowing through the cell refrigerant flow path 10 between the single cells. As shown in FIG. 2 (a), the cooling water temperature at both ends of the fuel cell 50 shown in FIG. The cooling water temperature Tx may be lower. At this time, regarding the cooling water temperature facing each single cell, the difference (ΔT) between the cooling water temperature on the cathode side (plus cooling water temperature) and the cooling water temperature on the anode side (minus cooling water temperature) The distribution in the stacking direction of the single cells is as shown in FIG. As shown in FIG. 2B, ΔT is positive at the minus-side laminated end and its vicinity.

  In this way, under the condition where ΔT is positive, the difference in the water vapor partial pressure is caused by the temperature difference between the anode side and the cathode side in the single cell, as described above, at the minus-side stack end and in the vicinity thereof. As a result, water vapor permeates from the cathode side to the anode side to generate condensed water on the anode side, and the pressure loss on the anode side increases (FIG. 2 (c)).

  FIG. 3 is a graph comparing the state of the single cells in the stacking direction when the temperature of the fuel cell 50 in the conventional fuel cell system is increased. In FIG. 3, the horizontal axis corresponds to FIG. Moreover, the vertical axis | shaft of Fig.3 (a), FIG.3 (b), and FIG.3 (c) respond | corresponds to Fig.2 (a), FIG.2 (b), and FIG.2 (c), respectively.

  As shown in FIG. 3 (a), when the temperature rises, the difference between the cooling water temperature and the cooling water temperature Tx ′ at the center of the stack is shown in FIG. It is larger than the steady operation shown. As a result, as shown in FIG. 3 (b), ΔT becomes large at the negative laminated end portion and its vicinity (for example, ΔT can be about 5 to 10 ° C.), and the partial pressure difference between the anode side and the cathode side is large. For example, it can be about several kPa to several tens of kPa. Since a large amount of water vapor permeates from the cathode side to the anode side based on this large water vapor partial pressure difference, the pressure loss distribution on the anode side becomes large as shown in FIG. The distribution flow rate of the anode gas flow path is reduced, and the voltage drop is likely to occur.

  On the other hand, compared with the pressure loss on the anode side in the conventional system indicated by the broken line in FIG. 4 (c), corresponding to FIG. 3 (c), as shown by the solid line in FIG. By controlling the pressure loss to increase and approaching the anode side pressure loss at the center of the stack as much as possible, the difference in cooling water temperature between the center of the stack and the end of the stack and its vicinity, that is, the temperature between the single cells Even when the difference remains large as in the past (see FIGS. 4A and 4B), it has become clear that it is possible to prevent or suppress a voltage drop due to temperature rise. Hereinafter, a more specific embodiment in which an increase in pressure loss on the anode side at the minus side laminated end portion and the vicinity thereof can be suppressed will be described.

[Embodiment 1]
In FIG. 1, the temperature state of the fuel cell 50 is monitored by the temperature sensor 28, and the supply amount of the oxidizing gas from the oxidizing gas supply device 20 by the controller 29 until the temperature of the fuel cell reaches a predetermined temperature from the start of temperature increase. To increase the control. Specifically, for example, it can be set to about 1.2 to 2 times, more preferably about 1.5 to 2 times the supply amount of the oxidizing gas during steady operation, but this is not restrictive. According to the present embodiment, by increasing the flow rate of the oxidizing gas supplied to the cathode side, water on the cathode side is taken away by the oxidizing gas before the water vapor permeates from the cathode side to the anode side, thereby moving the cathode side to the anode side. As a result, it is possible to suppress an increase in pressure loss on the anode side in the minus-side stacked end portion 11a and the single cell 11 in the vicinity thereof shown in FIG.

[Embodiment 2]
In FIG. 1, the temperature sensor 28 is monitored, and the controller 29 performs a control to decrease the amount of fuel gas supplied from the fuel gas supply device 19 until the temperature of the fuel cell reaches a predetermined temperature from the start of temperature increase. Specifically, it can be set to about 0.7 to 0.9 times the fuel gas supply amount during steady operation, but is not limited thereto. According to the present embodiment, by reducing the flow rate of fuel gas supplied to the anode side, the amount of moisture on the anode side taken away by the fuel gas is reduced, thereby suppressing the permeation of water vapor from the cathode side to the anode side. As a result, it is possible to suppress an increase in the pressure loss on the anode side in the minus side laminated end portion 11a shown in FIG. 5 and the unit cell 11 in the vicinity thereof.

[Embodiment 3]
In FIG. 1, the temperature sensor 28 is monitored, and the controller 29 controls the cathode side pressure regulating valve 24 to reduce the discharge pressure of the off-gas of the oxidizing gas from the start of the temperature rise until the temperature of the fuel cell reaches a predetermined temperature. I do. Specifically, the gauge pressure can be reduced to, for example, about 0.2 to 0.9 times the off-gas discharge pressure of the oxidizing gas discharged in a steady state, but is not limited thereto. According to this embodiment, by increasing the flow rate of the oxidizing gas discharged from the cathode side by lowering the discharge pressure, moisture on the cathode side can be removed before water vapor passes from the cathode side to the anode side. As a result, it is possible to reduce the amount of water vapor permeated from the cathode side to the anode side, and as a result, it is possible to suppress an increase in the pressure loss on the anode side in the minus side laminated end portion 11a shown in FIG. .

[Embodiment 4]
In FIG. 1, the temperature sensor 28 is monitored, and the controller 29 controls the anode-side pressure regulating valve 23 to increase the discharge pressure of the off-gas of the fuel gas until the temperature of the fuel cell reaches a predetermined temperature from the start of the temperature rise. I do. Specifically, for example, the gauge pressure can be increased to about 1.2 to 2 times, preferably about 1.5 to 2 times the discharge pressure of the off-gas of the fuel gas discharged in a steady state. Not limited to. According to the present embodiment, by increasing the discharge pressure, the flow rate of fuel gas discharged from the anode side is reduced, and the amount of moisture taken away by the fuel gas from the anode side is reduced, so that the anode side As a result, it is possible to suppress the increase in the pressure loss on the anode side in the minus-side stacked end portion 11a shown in FIG. 5 and the single cell 11 in the vicinity thereof.

[Embodiment 5]
It is also preferable to combine two or more of the first to fourth embodiments. Since the first to fourth embodiments described above are different controls that do not conflict with each other, for example, two or more controls such as the first and second embodiments and the first, third, and fourth embodiments can be performed in combination. Is possible. The present embodiment can obtain a particularly remarkable effect in, for example, a fuel cell system that frequently starts and stops and a fuel cell system that is mounted on a vehicle or other moving body and requires fine operation control. Become.

  In each of the above-described embodiments, the “predetermined temperature” of the fuel cell can be a temperature at which the fuel cell 50 shown in FIG. In other embodiments, in a cell stack in which the heat insulating properties of the stacked end portions are relatively good, it is possible to set the temperature somewhat lower than that during steady operation, such as 60 ° C., for example. As yet another embodiment, it is also preferable to detect whether or not the temperature is elevated based on a temperature difference between a predetermined time, for example, several milliseconds to several tens of seconds.

  The present invention is suitable for a fuel cell system including a cell stack capable of causing a temperature difference between a stacked central unit single cell and a stacked end unit single cell regardless of whether it is stationary or mounted on a moving body, particularly at the time of temperature rise. It is possible to use it.

It is a schematic diagram which shows the outline of a structure of the fuel cell system in embodiment of this invention. It is the graph which compared the state of the lamination direction of a single cell at the time of the steady operation of a fuel cell. It is the graph which compared the state of the lamination direction of a single cell at the time of temperature rising of the conventional fuel cell. It is the graph which compared the state of the lamination direction of a single cell at the time of temperature rising of a fuel cell. It is a schematic diagram which shows the outline of a structure of a fuel cell system. It is a figure explaining the outline of the structure of the principal part of a single cell.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Electrolyte membrane, 2 Anode catalyst layer, 3 Cathode catalyst layer, 4 Anode diffusion layer, 5 Cathode diffusion layer, 6 Anode side separator, 7 Cathode side separator, 8 Fuel gas flow path, 9 Oxidation gas flow path, 10 cell refrigerant flow Road, 11 single cell, 11a Minus side laminated end (single cell), 11c Plus side laminated end (single cell), 11g Laminated central part (single cell), 12 Cathode side current collector plate, 13 Anode side current collector plate 14, 15 Insulating plate, 16, 17 End plate, 18a Refrigerant supply manifold, 18b Refrigerant discharge manifold, 19 Fuel gas supply device, 20 Oxidizing gas supply device, 20a Oxidizing gas introduction path, 20b Oxidizing gas discharge path, 21, 22 Humidifier, 23, 24 Pressure regulating valve, 25, 26 Pressure sensor, 27 Cooling medium circulation device, 28 Temperature sensor, 29 Controller, 50 Fuel cell (cell stack), 100 Fuel cell system.

Claims (10)

A cell stack formed by laminating a plurality of unit cells having a fuel electrode and an oxidation electrode facing each other with an electrolyte membrane interposed therebetween;
Fuel gas supply means for supplying fuel gas to the cell stack;
A fuel gas introduction path for introducing the fuel gas from the fuel gas supply means into the cell stack;
A fuel gas discharge path for discharging the off-gas of the fuel gas accompanying the circulation of the fuel electrode of the fuel gas introduced into the cell stack to the outside of the cell stack;
An oxidizing gas supply means for supplying an oxidizing gas to the cell stack;
An oxidizing gas introduction path for introducing the oxidizing gas from the oxidizing gas supply means into the cell stack;
An oxidizing gas discharge path for discharging off-gas of the oxidizing gas accompanying the circulation of the oxidizing electrode of the oxidizing gas introduced into the cell stack to the outside of the cell stack;
Temperature state detecting means for detecting the temperature state of the cell stack;
During a power generation operation of a fuel cell including the cell stack, the temperature state detection is performed under a condition that a temperature difference between a refrigerant temperature flowing through the stack central portion of the cell stack and a refrigerant temperature flowing through both end portions of the stack becomes a predetermined value or more. A controller that performs control to suppress an increase in pressure loss on the fuel electrode side of the single cell according to a temperature increase of the cell stack sensed based on a temperature state detected by the means;
With
The controller removes moisture on the fuel electrode side by oxidizing gas before water vapor passes from the fuel electrode side to the oxidation electrode side in response to a rise in temperature of the cell stack, so that the oxidation from the fuel electrode side. A fuel cell system, characterized in that control is performed to increase an oxidizing gas supply flow rate from the oxidizing gas supply means so as to reduce a water vapor permeation amount to the pole side . A cell stack formed by laminating a plurality of unit cells having a fuel electrode and an oxidation electrode facing each other with an electrolyte membrane interposed therebetween;
Fuel gas supply means for supplying fuel gas to the cell stack;
A fuel gas introduction path for introducing the fuel gas from the fuel gas supply means into the cell stack;
A fuel gas discharge path for discharging the off-gas of the fuel gas accompanying the circulation of the fuel electrode of the fuel gas introduced into the cell stack to the outside of the cell stack;
An oxidizing gas supply means for supplying an oxidizing gas to the cell stack;
An oxidizing gas introduction path for introducing the oxidizing gas from the oxidizing gas supply means into the cell stack;
An oxidizing gas discharge path for discharging off-gas of the oxidizing gas accompanying the circulation of the oxidizing electrode of the oxidizing gas introduced into the cell stack to the outside of the cell stack;
Temperature state detecting means for detecting the temperature state of the cell stack;
During a power generation operation of a fuel cell including the cell stack, the temperature state detection is performed under a condition that a temperature difference between a refrigerant temperature flowing through the stack central portion of the cell stack and a refrigerant temperature flowing through both end portions of the stack becomes a predetermined value or more. A controller that performs control to suppress an increase in pressure loss on the fuel electrode side of the single cell according to a temperature increase of the cell stack sensed based on a temperature state detected by the means;
With
The controller performs control to reduce the fuel gas supply flow rate from the fuel gas supply means from the start of temperature increase until the temperature of the fuel cell reaches a predetermined temperature in response to the temperature increase of the cell stack. A fuel cell system. A cell stack formed by laminating a plurality of unit cells having a fuel electrode and an oxidation electrode facing each other with an electrolyte membrane interposed therebetween;
Fuel gas supply means for supplying fuel gas to the cell stack;
A fuel gas introduction path for introducing the fuel gas from the fuel gas supply means into the cell stack;
A fuel gas discharge path for discharging the off-gas of the fuel gas accompanying the circulation of the fuel electrode of the fuel gas introduced into the cell stack to the outside of the cell stack;
An oxidizing gas supply means for supplying an oxidizing gas to the cell stack;
An oxidizing gas introduction path for introducing the oxidizing gas from the oxidizing gas supply means into the cell stack;
An oxidizing gas discharge path for discharging off-gas of the oxidizing gas accompanying the circulation of the oxidizing electrode of the oxidizing gas introduced into the cell stack to the outside of the cell stack;
Temperature state detecting means for detecting the temperature state of the cell stack;
During a power generation operation of a fuel cell including the cell stack, the temperature state detection is performed under a condition that a temperature difference between a refrigerant temperature flowing through the stack central portion of the cell stack and a refrigerant temperature flowing through both end portions of the stack becomes a predetermined value or more. A controller that performs control to suppress an increase in pressure loss on the fuel electrode side of the single cell according to a temperature increase of the cell stack sensed based on a temperature state detected by the means;
With
Further comprising an oxidizing electrode side discharge pressure adjusting means capable of adjusting an oxidizing gas passage outlet pressure of the oxidizing gas off-gas from the cell stack;
The fuel cell system, wherein the controller performs control to reduce an off-gas outlet pressure of the oxidizing gas in accordance with a temperature rise of the cell stack. A cell stack formed by laminating a plurality of unit cells having a fuel electrode and an oxidation electrode facing each other with an electrolyte membrane interposed therebetween;
Fuel gas supply means for supplying fuel gas to the cell stack;
A fuel gas introduction path for introducing the fuel gas from the fuel gas supply means into the cell stack;
A fuel gas discharge path for discharging the off-gas of the fuel gas accompanying the circulation of the fuel electrode of the fuel gas introduced into the cell stack to the outside of the cell stack;
An oxidizing gas supply means for supplying an oxidizing gas to the cell stack;
An oxidizing gas introduction path for introducing the oxidizing gas from the oxidizing gas supply means into the cell stack;
An oxidizing gas discharge path for discharging off-gas of the oxidizing gas accompanying the circulation of the oxidizing electrode of the oxidizing gas introduced into the cell stack to the outside of the cell stack;
Temperature state detecting means for detecting the temperature state of the cell stack;
During a power generation operation of a fuel cell including the cell stack, the temperature state detection is performed under a condition that a temperature difference between a refrigerant temperature flowing through the stack central portion of the cell stack and a refrigerant temperature flowing through both end portions of the stack becomes a predetermined value or more. A controller that performs control to suppress an increase in pressure loss on the fuel electrode side of the single cell according to a temperature increase of the cell stack sensed based on a temperature state detected by the means;
With
A fuel electrode side discharge pressure adjusting means capable of adjusting the fuel gas flow path outlet pressure of the off gas of the fuel gas from the cell stack;
The fuel cell system, wherein the controller performs control to increase an off-gas outlet pressure of the fuel gas according to a temperature rise of the cell stack. The fuel cell system according to any one of claims 1 to 4 ,
A refrigerant flow path for introducing a cooling medium to be used for heat exchange with the single cell into the cell stack, and for discharging the cooling medium heat-exchanged with the single cell to the outside of the cell stack; Prepared,
The fuel cell system, wherein the temperature state detection means includes a temperature sensor capable of detecting a coolant temperature near an outlet from the cell stack. A cell stack control method comprising a plurality of unit cells each having a fuel electrode and an oxidation electrode facing each other with an electrolyte membrane interposed therebetween,
A fuel gas introduction step for introducing fuel gas into the cell stack;
A fuel gas discharging step of discharging the fuel gas introduced into the cell stack to the outside of the cell stack, off-gas of the fuel gas accompanying the circulation of the fuel electrode;
An oxidizing gas introduction step for introducing an oxidizing gas into the cell stack;
An oxidizing gas discharging step of discharging the oxidizing gas introduced into the cell stack to the outside of the cell stack, the oxidizing gas off-gas accompanying the circulation of the oxidizing electrode;
A temperature rise sensing step for sensing temperature rise of the single cell;
During the power generation operation of the fuel cell including the cell stack, the detected unit is detected under a condition in which the temperature difference between the refrigerant temperature flowing through the center of the stack of the cell stack and the refrigerant temperature flowing through both ends of the stack becomes a predetermined value or more. A step of suppressing an increase in pressure loss on the fuel electrode side in accordance with the temperature rise of the cell;
I have a,
The step of suppressing an increase in pressure loss on the fuel electrode side includes removing moisture on the fuel electrode side by oxidizing gas before water vapor permeates from the fuel electrode side to the oxidation electrode side. A control method comprising the step of increasing the amount of the oxidizing gas introduced so as to reduce the amount of water vapor permeated to the side . A cell stack control method comprising a plurality of unit cells each having a fuel electrode and an oxidation electrode facing each other with an electrolyte membrane interposed therebetween,
A fuel gas introduction step for introducing fuel gas into the cell stack;
A fuel gas discharging step of discharging the fuel gas introduced into the cell stack to the outside of the cell stack, off-gas of the fuel gas accompanying the circulation of the fuel electrode;
An oxidizing gas introduction step for introducing an oxidizing gas into the cell stack;
An oxidizing gas discharging step of discharging the oxidizing gas introduced into the cell stack to the outside of the cell stack, the oxidizing gas off-gas accompanying the circulation of the oxidizing electrode;
A temperature rise sensing step for sensing temperature rise of the single cell;
During the power generation operation of the fuel cell including the cell stack, the detected unit is detected under a condition in which the temperature difference between the refrigerant temperature flowing through the center of the stack of the cell stack and the refrigerant temperature flowing through both ends of the stack becomes a predetermined value or more. A step of suppressing an increase in pressure loss on the fuel electrode side in accordance with the temperature rise of the cell;
Have
The control method characterized in that the step of suppressing an increase in pressure loss on the fuel electrode side includes a step of reducing the amount of fuel gas introduced from the start of temperature rise until the temperature of the fuel cell reaches a predetermined temperature . A cell stack control method comprising a plurality of unit cells each having a fuel electrode and an oxidation electrode facing each other with an electrolyte membrane interposed therebetween,
A fuel gas introduction step for introducing fuel gas into the cell stack;
A fuel gas discharging step of discharging the fuel gas introduced into the cell stack to the outside of the cell stack, off-gas of the fuel gas accompanying the circulation of the fuel electrode;
An oxidizing gas introduction step for introducing an oxidizing gas into the cell stack;
An oxidizing gas discharging step of discharging the oxidizing gas introduced into the cell stack to the outside of the cell stack, the oxidizing gas off-gas accompanying the circulation of the oxidizing electrode;
A temperature rise sensing step for sensing temperature rise of the single cell;
During the power generation operation of the fuel cell including the cell stack, the detected unit is detected under a condition in which the temperature difference between the refrigerant temperature flowing through the center of the stack of the cell stack and the refrigerant temperature flowing through both ends of the stack becomes a predetermined value or more. A step of suppressing an increase in pressure loss on the fuel electrode side in accordance with the temperature rise of the cell;
Have
The step of suppressing the increase in pressure loss on the fuel electrode side includes the step of reducing the discharge pressure of the off-gas of the oxidizing gas from the cell stack. A cell stack control method comprising a plurality of unit cells each having a fuel electrode and an oxidation electrode facing each other with an electrolyte membrane interposed therebetween,
A fuel gas introduction step for introducing fuel gas into the cell stack;
A fuel gas discharging step of discharging the fuel gas introduced into the cell stack to the outside of the cell stack, off-gas of the fuel gas accompanying the circulation of the fuel electrode;
An oxidizing gas introduction step for introducing an oxidizing gas into the cell stack;
An oxidizing gas discharging step of discharging the oxidizing gas introduced into the cell stack to the outside of the cell stack, the oxidizing gas off-gas accompanying the circulation of the oxidizing electrode;
A temperature rise sensing step for sensing temperature rise of the single cell;
During the power generation operation of the fuel cell including the cell stack, the detected unit is detected under a condition in which the temperature difference between the refrigerant temperature flowing through the center of the stack of the cell stack and the refrigerant temperature flowing through both ends of the stack becomes a predetermined value or more. A step of suppressing an increase in pressure loss on the fuel electrode side in accordance with the temperature rise of the cell;
Have
The step of suppressing an increase in pressure loss on the fuel electrode side includes a step of increasing a discharge pressure of the off-gas of the fuel gas from the cell stack. The control method according to any one of claims 6 to 9 ,
A refrigerant circulation step of introducing a cooling medium used for heat exchange with the single cell into the cell stack and discharging the cooling medium heat-exchanged with the single cell to the outside of the cell stack; Have
The control method, wherein the temperature increase sensing step includes a step of detecting a temperature of the cooling medium discharged to the outside of the cell stack.

Images