JP2007323993A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To promptly uniformalize temperature of a fuel cell stack without making the whole system large in size and simplifying the system structure by using a plurality of cooling means which correspond to each of a plurality of portions of the fuel cell stack and can adjust cooling capacity mutually independently and controlling the cooling capacity of the cooling means corresponding to the portions where the temperature of the fuel cell stack deviates partially. <P>SOLUTION: The fuel cell system comprises a fuel cell stack in which a fuel cell interposing an electrolyte layer by a fuel electrode and an oxygen electrode is laminated interposing a separator in which a fuel gas passage is formed along the fuel electrode and an air passage is formed along the oxygen electrode, a temperature detector which detects temperature of a plurality of portions of the fuel cell stack, a plurality of cooling means which correspond respectively to the plurality of portions of the fuel cell stack and can adjust cooling capacity mutually independently, and a control means which controls the cooling capacity of the cooling means corresponding to the portions where the temperature of the fuel cell stack deviates partially and uniformalizes the temperature of the fuel cell stack. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell system.

  Conventionally, since fuel cells have high power generation efficiency and do not emit harmful substances, they have been put into practical use as power generators for industrial and household use, or as power sources for artificial satellites and spacecrafts. Development is progressing as a power source for vehicles such as buses, trucks, passenger carts, and luggage carts. The fuel cell may be of an alkaline aqueous solution type (AFC), phosphoric acid type (PAFC), molten carbonate type (MCFC), solid oxide type (SOFC), direct methanol (DMFC), or the like. Although good, a polymer electrolyte fuel cell (PEMFC) is common.

  In this case, the solid polymer electrolyte membrane is sandwiched between two gas diffusion electrodes and integrated to join. When one of the gas diffusion electrodes is used as a fuel electrode (anode electrode) and hydrogen gas as fuel is supplied to the surface thereof, hydrogen is decomposed into hydrogen ions (protons) and electrons, and the hydrogen ions are converted into a solid polymer electrolyte. Permeates the membrane. Further, when the other of the gas diffusion electrodes is an oxygen electrode (cathode electrode) and air as an oxidant is supplied to the surface, oxygen in the air is combined with the hydrogen ions and electrons to generate water. The An electromotive force is generated by such an electrochemical reaction.

By the way, since the electrochemical reaction of the fuel cell is accompanied by heat generation, for example, when a fuel cell stack is configured by stacking a large number of fuel cells, temperature variations may occur in each part. When temperature variation occurs, the performance of the portion where the temperature has risen is degraded, and the performance of the entire fuel cell is degraded or the life is shortened. Therefore, in a fuel cell system in which the periphery of the fuel cell is covered with a case in order to ventilate the hydrogen gas leaked from the fuel cell, the flow rate of the ventilation air introduced into the case is set according to the temperature of the fuel cell. A technique for adjustment has been proposed (see, for example, Patent Document 1).
JP 2004-192889 A

  However, in the conventional fuel cell system, since it is necessary to cover the periphery of the fuel cell with a case and supply air for ventilation into the case, the entire system becomes large and complicated. In addition, since the flow rate of the ventilation air flowing through the entire area of the case is adjusted, it is difficult to quickly and appropriately respond to the local temperature change of the fuel cell.

  The present invention solves the problems of the conventional fuel cell system, uses a plurality of cooling means respectively corresponding to a plurality of portions of the fuel cell stack and independently adjusting the cooling capacity, and By adjusting the cooling capacity of the cooling means corresponding to the part where the temperature is unevenly distributed, the system structure can be simplified without increasing the size of the entire system, and the temperature of the fuel cell stack can be made uniform quickly. An object of the present invention is to provide a fuel cell system that can be used.

  Therefore, in the fuel cell system of the present invention, a fuel cell in which an electrolyte layer is sandwiched between a fuel electrode and an oxygen electrode has a fuel gas flow path formed along the fuel electrode, and an air flow along the oxygen electrode. A fuel cell stack that is stacked with a separator having a path formed therebetween, a temperature detector that detects temperatures of a plurality of portions of the fuel cell stack, and each of the plurality of portions of the fuel cell stack, each independently A plurality of cooling means capable of adjusting the cooling capacity and control means for adjusting the cooling capacity of the cooling means corresponding to the portion where the temperature of the fuel cell stack is unevenly distributed to equalize the temperature of the fuel cell stack. .

  In another fuel cell system of the present invention, the cooling means is a fan for supplying air to the air flow path.

  In still another fuel cell system of the present invention, the cooling means is a nozzle for supplying water to the air flow path, and the control means is a water supply for a nozzle corresponding to a portion where the temperature of the fuel cell stack is high. Increase the volume and decrease the water supply of the nozzle corresponding to the low temperature part.

  In still another fuel cell system of the present invention, a fuel cell having an electrolyte layer sandwiched between a fuel electrode and an oxygen electrode has a fuel gas flow path formed along the fuel electrode, and an air flow along the oxygen electrode. A fuel cell stack stacked with a separator having a path formed therein, a voltage detector for detecting a terminal voltage of a plurality of portions of the fuel cell stack, and each of the plurality of portions of the fuel cell stack, and independent of each other A plurality of cooling means capable of adjusting the cooling capacity, and a control means for adjusting the cooling capacity of the cooling means corresponding to the portion where the output of the fuel cell stack is unevenly distributed.

  In still another fuel cell system of the present invention, the control means further adjusts the cooling capacity of the cooling means in accordance with a history of changes in the output of the fuel cell stack.

  In still another fuel cell system of the present invention, the fuel cell system further includes a temperature detector that detects temperatures of a plurality of portions of the fuel cell stack, and the control means includes: From the above, the cause of the output decrease in the low output portion is specified, and the cooling capacity of the cooling means is adjusted.

  According to the present invention, in the fuel cell system, the fuel cell in which the electrolyte layer is sandwiched between the fuel electrode and the oxygen electrode has a fuel gas flow path formed along the fuel electrode, and an air flow along the oxygen electrode. A fuel cell stack that is stacked with a separator having a path formed therebetween, a temperature detector that detects temperatures of a plurality of portions of the fuel cell stack, and each of the plurality of portions of the fuel cell stack, each independently A plurality of cooling means capable of adjusting the cooling capacity and control means for adjusting the cooling capacity of the cooling means corresponding to the portion where the temperature of the fuel cell stack is unevenly distributed to equalize the temperature of the fuel cell stack. .

  In this case, the temperature of the fuel cell stack can be made uniform quickly, occurrence of water clogging can be prevented, and the output of the entire fuel cell stack can be increased.

  In another fuel cell system, the cooling means is a fan for supplying air to the air flow path.

  In this case, since a large amount of air is supplied to the high temperature portion of the fuel cell stack, the amount of heat taken away by the air increases, and the temperature of the portion decreases. In addition, the humidity increases and the output of the portion increases.

  In still another fuel cell system, the cooling means is a nozzle for supplying water to the air flow path, and the control means increases the amount of water supplied to the nozzle corresponding to a portion where the temperature of the fuel cell stack is high. To reduce the amount of water supplied to the nozzle corresponding to the low temperature portion.

  In this case, since a large amount of water is supplied to the high temperature portion of the fuel cell stack, the amount of heat taken away by the water increases, and the temperature of the portion decreases. Also, the humidity rises quickly and the output of the part increases.

  In still another fuel cell system, a fuel cell in which an electrolyte layer is sandwiched between a fuel electrode and an oxygen electrode has a fuel gas flow path formed along the fuel electrode and an air flow path formed along the oxygen electrode. The fuel cell stacks stacked with the separators interposed therebetween, the voltage detector for detecting the terminal voltage of the plurality of portions of the fuel cell stack, and the plurality of portions of the fuel cell stack, respectively, are cooled independently of each other A plurality of cooling means capable of adjusting the capacity, and a control means for adjusting the cooling capacity of the cooling means corresponding to the portion where the output of the fuel cell stack is unevenly distributed.

  In this case, the uneven distribution of the temperature of the fuel cell stack can be grasped without using a temperature detector. And the temperature of a fuel cell stack can be equalized rapidly, generation | occurrence | production of water clogging can be prevented, and the output of the whole fuel cell stack can be increased.

  In still another fuel cell system, the control means further adjusts the cooling capacity of the cooling means in accordance with the history of changes in the output of the fuel cell stack.

  In this case, it is possible to accurately grasp a portion where the temperature is high and dry in the fuel cell stack, lower the temperature of the portion, increase the humidity, and increase the output of the portion.

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

  FIG. 1 is a three-side view showing the configuration of a fuel cell system in an embodiment of the present invention. 1A is a side view, FIG. 1B is a top view, and FIG. 1C is a front view.

  In the figure, reference numeral 11 denotes a fuel cell stack composed of a plurality of fuel battery cells (FC), which is used as a power source for vehicles such as passenger cars, buses, trucks, passenger carts, and luggage carts. Here, the vehicle is equipped with a large number of auxiliary devices that consume electricity, such as lighting devices, radios, and power windows, which are used even when the vehicle is stopped. Since the output range is extremely wide, it is desirable to use the fuel cell stack 11 as a power source in combination with the power storage means including a battery, a capacitor and the like.

  The fuel cell stack 11 may be of an alkaline aqueous solution type, a phosphoric acid type, a molten carbonate type, a solid oxide type, a direct type methanol or the like, but is preferably a solid polymer type fuel cell. .

  More preferably, PEMFC (Proton Exchange Membrane Fuel Cell) type fuel cell or PEM (Proton Exchange Membrane) using hydrogen gas as fuel gas, that is, anode gas, and oxygen or air as oxidant, that is, cathode gas. ) Type fuel cell. Here, the PEM fuel cell is generally a fuel cell in which a catalyst, an electrode, and a separator are combined on both sides of a solid polymer electrolyte membrane as an electrolyte layer that transmits ions such as protons. Are composed of a plurality of stacks connected in series.

  In the present embodiment, the fuel cell stack 11 is a unit cell (MEA: MEMBRANE ELECTRODE ASSEMBLY) as a fuel cell and the unit cells are electrically connected to each other and introduced into the unit cell as an anode gas. The separator for separating the hydrogen gas flow path and the air flow path as the cathode gas is set as one set, and a plurality of sets are stacked in the thickness direction.

  The unit cell includes an air electrode as an oxygen electrode provided on one side of the solid polymer electrolyte membrane as an electrolyte layer and a fuel electrode provided on the other side. The air electrode and the fuel electrode include an electrode diffusion layer made of a conductive material that permeates while diffusing the reaction gas, and a catalyst layer formed on the electrode diffusion layer and supported in contact with the solid polymer electrolyte membrane. Consists of. In addition, the current collector in contact with the electrode diffusion layer on the air electrode side of the unit cell and the air electrode side collector as a net-like current collector formed with a large number of openings through which a mixed flow of air and water is transmitted; And a current collector in contact with the electrode diffusion layer on the fuel electrode side of the unit cell, and a fuel electrode side collector as a net-like current collector having a large number of openings through which hydrogen gas permeates.

  In the unit cell, water moves. In this case, when fuel gas, that is, hydrogen gas as anode gas, is supplied into a fuel chamber as a hydrogen gas flow path formed on the fuel electrode side of the separator, hydrogen is decomposed into hydrogen ions and electrons, Permeates the solid polymer electrolyte membrane with proton-entrained water. Further, when the air electrode is used as a cathode electrode and an oxidant, that is, air as a cathode gas, is supplied into an oxygen chamber as an air flow path, oxygen in the air is combined with the hydrogen ions and electrons to form water. Is generated. Moisture permeates through the solid polymer electrolyte membrane as reverse diffusion water and moves into the fuel chamber. Here, the reverse diffusion water means that water generated in the oxygen chamber diffuses into the solid polymer electrolyte membrane and permeates into the fuel chamber through the solid polymer electrolyte membrane in the direction opposite to the hydrogen ions. It is a thing.

  The fuel cell stack 11 is supplied with hydrogen gas as a fuel gas by a fuel supply system (not shown). Although hydrogen gas, which is fuel taken out by reforming methanol, gasoline, or the like by the reformer, can be directly supplied to the fuel cell stack 11, a sufficient amount can be stably provided even during high-load operation of the vehicle. In order to be able to supply hydrogen gas, it is desirable to supply hydrogen gas stored in the fuel storage means. Thereby, the hydrogen gas is always sufficiently supplied at a substantially constant pressure, so that the fuel cell stack 11 can follow the fluctuation of the load of the vehicle and supply a necessary current. .

  Hydrogen gas is supplied from a fuel storage means such as a container containing a hydrogen storage alloy, a container containing a hydrogen storage liquid such as decalin, a hydrogen gas cylinder, etc., through a fuel supply line, and a fuel gas flow path of the fuel cell stack 11. Supplied to the entrance. In this case, the fuel storage means has a sufficiently large capacity and always has a capability of supplying hydrogen gas at a sufficiently high pressure. A fuel supply on / off valve, a pressure sensor, a fuel pressure adjustment valve, and the like are disposed in the fuel supply line.

  Further, hydrogen gas discharged as an unreacted component from the outlet of the fuel gas flow path of the fuel cell stack 11 is discharged out of the fuel cell stack 11 through the fuel discharge pipe. A water recovery drain tank as a recovery container is disposed in the fuel discharge pipe. The water recovery drain tank is connected to a fuel discharge pipe for discharging hydrogen gas separated from water, and the end of the fuel discharge pipe opposite to the water recovery drain tank is connected to the fuel supply pipe. It is desirable that Thereby, the hydrogen gas discharged out of the fuel cell stack 11 can be recovered, supplied to the fuel gas flow path of the fuel cell stack 11 and reused.

  The water recovery drain tank is connected to a starting fuel discharge pipe, and hydrogen gas discharged from the fuel gas flow path when the fuel cell stack 11 is started can be discharged into the atmosphere. Yes. In addition, an electromagnetic on-off valve or the like is provided in the fuel discharge line and the start fuel discharge line so that the flow of hydrogen gas discharged out of the fuel cell stack 11 can be controlled. In addition, a suction circulation pump or the like is provided in the middle of the fuel discharge pipe, and the hydrogen gas discharged from the outlet of the fuel gas flow path of the fuel cell stack 11 is forcibly sucked into the fuel. The inside of the gas flow path may be in a negative pressure state or the discharged hydrogen gas may be circulated.

  On the other hand, the air as the oxidant passes through an air filter (not shown) and is sucked into the fan 22 as the oxidant supply source, and is attached to the upper side of the fuel cell stack 11, that is, the air inlet side as the oxidant inlet side. The air is supplied into the air supply chamber 12. The air supply chamber 12 is a cylindrical body having a rectangular cross section in the illustrated example, but has a cross section having the same shape and area as the air inlet side surface of the fuel cell stack 11. Any shape can be used.

  In the present embodiment, there are a plurality of the fans 22, which are arranged so as to face the air inlet side surface of the fuel cell stack 11, and each fan 22 supplies air to each part of the opposed fuel cell stack 11. It is like that. In the illustrated example, there are fifteen fans 22, which are arranged at equal intervals, and supply air to portions corresponding to each fan 22 in the fuel cell stack 11, respectively. The air supplied by the fan 22 is supplied to the oxygen chamber of the fuel cell stack 11, that is, the air flow path, and functions as an oxidant. The air supplied by the fan 22 also has a function of cooling the fuel cell stack 11. That is, each of the fans 22 also functions as a cooling unit that cools a corresponding portion of the fuel cell stack 11 by supplying air.

  A plurality of nozzles 23 are disposed in the air supply chamber 12 so as to face the air inlet side surface of the fuel cell stack 11, and each nozzle 23 supplies water to each part of the opposed fuel cell stack 11. It is supposed to be. The nozzle 23 is supplied with water stored in a water tank by a water supply pump (not shown). By spraying and supplying water from the nozzle 23 into the air supplied to the air flow path of the fuel cell stack 11, the air electrode as the oxygen electrode of the fuel cell stack 11 can be maintained in a wet state. . In the illustrated example, eight nozzles 23 are arranged at equal intervals between the fans 22, and water is supplied to portions corresponding to the respective nozzles 23 in the fuel cell stack 11. The water supplied by the nozzle 23 also has a function of cooling the fuel cell stack 11. That is, each of the nozzles 23 also functions as a cooling unit that cools a corresponding portion of the fuel cell stack 11 by supplying water.

  The air discharged from the air flow path of the fuel cell stack 11 is discharged into the air discharge chamber 13 attached to the lower side of the fuel cell stack 11, that is, the air outlet side as the oxidant outlet side. The air is discharged into the atmosphere through the connection duct 14 and the exhaust duct 15 connected to the air discharge chamber 13. It is desirable that a condenser is provided in the exhaust duct 15 to cool and separate the recovered moisture by cooling the air discharged from the fuel cell stack 11. The recovered water is returned to the water tank, and the water can be effectively reused by spraying water from the nozzle 23 again through the water supply pipe connected to the water tank. Can be miniaturized.

  The air discharge chamber 13 is a cylindrical body having a rectangular cross-sectional shape in the illustrated example, but is preferably provided with a cross-section having the same shape and area as the air outlet side surface of the fuel cell stack 11. Better. In the air discharge chamber 13, a plurality of temperature detectors 21 are disposed so as to face the air outlet side surface of the fuel cell stack 11, and each temperature detector 21 has an air flow of the opposed fuel cell stack 11. The temperature of the air exhausted from the road is detected. In the illustrated example, there are 15 temperature detectors 21 arranged at equal intervals in the same manner as the fans 22, and detect the temperature of the air discharged from the portion corresponding to each fan 22 in the fuel cell stack 11. To do. Thereby, each temperature detector 21 can detect the temperature of each corresponding part of the fuel cell stack 11.

  In addition, the number of the said fan 22, the nozzle 23, and the temperature detector 21 and the aspect of arrangement | positioning can be set arbitrarily.

  In the present embodiment, the operation of each fan 22 can be controlled independently, the air volume of each fan 22 can be adjusted independently, and the ability to cool the corresponding part of the fuel cell stack 11 can be adjusted. Can do. Thereby, the temperature of the desired part of the fuel cell stack 11 can be adjusted. Similarly, the operation of each nozzle 23 can also be controlled independently, the water supply amount of each nozzle 23 can be adjusted independently, and the ability to cool the corresponding part of the fuel cell stack 11 can be adjusted. . Thereby, the temperature of the desired part of the fuel cell stack 11 can be adjusted. Furthermore, the ability to cool the fuel cell stack 11 can be adjusted by adjusting the amount of hydrogen gas supplied to the fuel gas flow path of the fuel cell stack 11. In this case, a fuel gas supply / opening valve, a fuel pressure regulating valve, an electromagnetic on / off valve, a suction circulation pump, etc. provided in the fuel discharge line and the starting fuel discharge line are supplied with the fuel gas. It functions as a quantity adjusting means.

  Further, by attaching a voltage detector (not shown) to a plurality of unit cells of the fuel cell stack 11, a terminal voltage in each part of the fuel cell stack 11, that is, a single cell voltage that is an electromotive force of the unit cell is detected. Can do. Usually, when the temperature of the unit cell rises, the cell voltage decreases. Therefore, the temperature change in each part of the fuel cell stack 11 can be grasped by the voltage detected by the voltage detector.

  In the present embodiment, the fuel cell system has control means (not shown). The control means includes arithmetic means such as a CPU and MPU, storage means such as a semiconductor memory, an input / output interface, and the like, and is supplied to the fuel cell stack 11 from a temperature detector 21, a pressure sensor, a voltage detector, and other sensors. Detecting the flow rate, temperature, output voltage, etc. of hydrogen, air, water, etc., such as the fan 22, nozzle 23, fuel supply on / off valve, fuel pressure regulating valve, electromagnetic on / off valve, suction circulation pump, water supply pump, etc. Control the behavior. Furthermore, the control means controls the operation of the fuel cell system in an integrated manner in cooperation with other sensors and other control means.

  Next, the operation of the fuel cell system having the above configuration will be described.

  FIG. 2 is a graph showing the relationship between fuel cell performance and temperature and humidity in the embodiment of the present invention, and FIG. 3 is a single cell voltage when the performance of a part of the fuel cell stack in the embodiment of the present invention is degraded. It is a graph which shows the change of.

  The output of the polymer electrolyte fuel cell is affected by temperature and humidity. FIG. 2 is a graph obtained by plotting the relationship between fuel cell performance and temperature and humidity through experiments conducted by the inventor of the present invention. Curved surface A shows the performance of the fuel cell varying with temperature and humidity. It shows how to do. In FIG. 2, the vertical axis represents the voltage [V] when the current per unit area is 1.0 [A], and the horizontal axis represents the temperature [° C.] and the humidity [% RH]. It is.

  FIG. 2 shows that the performance of the fuel cell is most deteriorated when the temperature rises and the humidity decreases. In general fuel cell operating conditions, when the temperature rises, the moisture in the air electrode and the fuel electrode of the solid polymer electrolyte membrane evaporates and the humidity decreases. Therefore, in the present embodiment, only the case where the decrease in the performance of the fuel cell is grasped by focusing only on the temperature of the fuel cell detected by the temperature detector 21 will be described.

  Also, when viewed in detail, the temperature may be different between the air electrode side and the fuel electrode side of the solid polymer electrolyte membrane, but since the cell reaction in the fuel cell occurs on the air electrode side, It is desirable to adjust the temperature on the air electrode side by paying attention to the temperature. Therefore, in the present embodiment, each temperature of the fuel cell stack 11 is detected by detecting the temperature of the air discharged from the air flow path formed on the air electrode side of the solid polymer electrolyte membrane with the temperature detector 21. Grasp as the temperature of the part. Further, by adjusting the air volume of each fan 22 and the water supply amount of each nozzle 23, the temperature on the air electrode side of the solid polymer electrolyte membrane in each part of the fuel cell stack 11 is mainly adjusted.

  First, at the time of steady operation in the fuel cell system, the control means monitors the detected temperature of each part of the fuel cell stack 11 based on the output signal from each temperature detector 21. Then, when grasping that the temperature is unevenly distributed, that is, grasping that the temperature of any part of the fuel cell stack 11 is higher or lower than the other part, the relevant part The operation of the fan 22 and / or the nozzle 23 corresponding to the above is controlled to adjust the cooling capacity, and the temperature of the part is made equal to the temperature of the other part. That is, the temperature of the fuel cell stack 11 is made uniform.

  As described above, since the performance degradation when the temperature is high is larger than the performance degradation when the temperature of the fuel cell is low, the temperature of any part of the fuel cell stack 11 is the other part here. Only the operation in the case of higher than that will be described.

  When the temperature of any part of the fuel cell stack 11 is higher than the other part, the control means increases the air volume of the fan 22 corresponding to the part. Thereby, since more air is supplied to the air flow path in the high temperature part of the fuel cell stack 11, the amount of heat taken away by the air increases, and the temperature of the part decreases. Further, the humidity of the solid polymer electrolyte membrane also increases, and the output of the portion increases. When the temperature detected by the temperature detector 21 corresponding to the part becomes equal to the temperature of the other part, the air volume of the fan 22 is returned to normal. In this way, the temperature of the fuel cell stack 11 can be made uniform, and the output of the entire fuel cell stack 11 can be increased.

  Similarly, when the temperature of any part of the fuel cell stack 11 is higher than the other part, the control means can also increase the amount of water supplied to the nozzle 23 corresponding to that part. As a result, a large amount of water is supplied to the air flow path in the portion where the temperature of the fuel cell stack 11 is high, so that the amount of heat taken away by the water increases and the temperature of the portion decreases. In addition, the humidity of the solid polymer electrolyte membrane also rises quickly, and the output of the portion increases. And if the temperature detected by the temperature detector 21 corresponding to the said part becomes equivalent to the temperature of another part, the water supply amount of the said nozzle 23 will be returned to normal. In this way, the temperature of the fuel cell stack 11 can be made uniform, and the output of the entire fuel cell stack 11 can be increased.

  Furthermore, when the temperature of any part of the fuel cell stack 11 is higher than the other parts, the control unit increases the air volume of the fan 22 corresponding to the part and also increases the water supply amount of the nozzle 23. It can also be made. Thereby, since more air and water are supplied to the air flow path in the high temperature part of the fuel cell stack 11, the amount of heat taken away by the air and water increases, and the temperature of the part rapidly decreases. In addition, the humidity of the solid polymer electrolyte membrane also rises quickly, and the output of the portion increases. When the temperature detected by the temperature detector 21 corresponding to the part becomes equal to the temperature of the other part, the air volume of the fan 22 and the water supply amount of the nozzle 23 are returned to normal. In this way, the temperature of the fuel cell stack 11 can be made uniform quickly, and the output of the entire fuel cell stack 11 can be increased.

  In addition, in the part with the low temperature of the fuel cell stack 11, it is possible that the water produced | generated in the air flow path, ie, produced water, has condensed. Therefore, when the water supply amount of the nozzle 23 is adjusted to make the temperature of the fuel cell stack 11 uniform, the water supply amount of the nozzle 23 corresponding to the portion where the temperature is lower than the other portions may be reduced. desirable. Thereby, the occurrence of water clogging at a low temperature portion can be prevented.

  As described above, when the temperature rises, the performance of the fuel cell deteriorates. Therefore, the output is unevenly distributed due to the uneven distribution of the temperature of the fuel cell stack 11 due to the voltage detected by the voltage detector. I can grasp that. In this case, the cost can be reduced by omitting the temperature detector 21.

  FIG. 3 is a graph obtained by plotting the change of each single cell voltage when the inventor of the present invention conducts an experiment and the temperature of a part of the fuel cell rises. It can be seen that the single cell voltage at the portion where the temperature has increased is lower than the single cell voltage at the other portion. In addition, it is considered that the output of the fuel cell is decreased because the temperature is increased and the electrolyte membrane is dried, or the generated water blocks the gas dew. Only the operation in the case where the output is reduced due to the temperature rise in the part will be described.

  In this case, when the terminal voltage of any part of the fuel cell stack 11 decreases, the control means increases the air volume of the fan 22 corresponding to the part. Thereby, since more air is supplied to the air flow path in the high temperature part of the fuel cell stack 11, the amount of heat taken away by the air increases, and the temperature of the part decreases. In addition, the humidity of the solid polymer electrolyte membrane also increases, the output of the portion increases, and the terminal voltage increases. When the terminal voltage becomes equal to the terminal voltage of the other part by the voltage detector corresponding to the part, the air volume of the fan 22 is returned to normal. In this way, the temperature of the fuel cell stack 11 can be made uniform, and the output of the entire fuel cell stack 11 can be increased.

  Similarly, when the terminal voltage of any part of the fuel cell stack 11 is low, the control means can also increase the water supply amount of the nozzle 23 corresponding to the part. As a result, a large amount of water is supplied to the air flow path in the portion where the temperature of the fuel cell stack 11 is high, so the amount of heat taken away by the water increases and the temperature of the portion decreases. In addition, the humidity of the solid polymer electrolyte membrane also increases, the output of the portion increases, and the terminal voltage increases. And if the terminal voltage becomes equivalent to the terminal voltage of another part by the voltage detector corresponding to the said part, the water supply amount of the said nozzle 23 will be returned to normal. In this way, the temperature of the fuel cell stack 11 can be made uniform, and the output of the entire fuel cell stack 11 can be increased.

  Furthermore, when the terminal voltage of any part of the fuel cell stack 11 is low, the control unit can increase the air volume of the fan 22 corresponding to the part and also increase the water supply amount of the nozzle 23. . Thereby, since more air and water are supplied to the air flow path in the high temperature part of the fuel cell stack 11, the amount of heat taken away by the air and water increases, and the temperature of the part rapidly decreases. In addition, the humidity of the solid polymer electrolyte membrane also increases, the output of the portion increases, and the terminal voltage rises quickly. Then, when the terminal voltage becomes equal to the terminal voltage of the other part by the voltage detector corresponding to the part, the air volume of the fan 22 and the water supply amount of the nozzle 23 are returned to normal. In this way, the temperature of the fuel cell stack 11 can be made uniform quickly, and the output of the entire fuel cell stack 11 can be increased.

  In addition, the ability to cool the fuel cell stack 11 can be adjusted by adjusting the amount of hydrogen gas supplied to the fuel gas flow path of the fuel cell stack 11. In a general fuel cell operation situation, the hydrogen gas in the fuel gas channel hardly flows and is substantially stagnant in the fuel gas channel. Therefore, the amount of hydrogen gas supplied to the fuel gas flow path is increased by operating a fuel supply on / off valve, a fuel pressure adjusting valve, an electromagnetic on / off valve, a suction circulation pump, etc. that function as fuel gas supply amount adjusting means, When the hydrogen gas in the fuel gas channel is caused to flow, the amount of heat taken away by the hydrogen gas increases and the temperature in the fuel gas channel decreases.

  In this case, if it is determined that the terminal voltage is decreased and the output of the fuel cell stack 11 is decreased, the control means operates the fuel supply on / off valve, the fuel pressure adjusting valve, the electromagnetic on / off valve, the suction circulation pump, and the like. Thus, the amount of hydrogen gas supplied to the fuel gas passage is increased. As a result, a large amount of hydrogen gas is supplied to the fuel gas flow path of the fuel cell stack 11, so that the amount of heat taken away by the hydrogen gas increases, the temperature of the fuel cell stack 11 decreases, and the output of the fuel cell stack 11 decreases. Increases and the terminal voltage rises. When it is determined that the output of the fuel cell stack 11 has been restored based on the terminal voltage detected by the voltage detector, the amount of hydrogen gas is returned to normal.

  In addition, it is possible to specify the cause of the output decrease in the low output part from the output change history of the fuel cell stack 11 and adjust the temperature of the fuel cell stack 11. The history is a record of changes in terminal voltage in each part of the fuel cell stack 11 over a predetermined period from the past to the present time, and is stored in a storage means provided in the control means.

  When the terminal voltage of any part of the fuel cell stack 11 is low, the control unit checks the recording of the terminal voltage of the part, and when the terminal voltage is gradually decreasing, that is, the output is moderately When it is lowered, it is determined that the temperature of the portion is high and the solid polymer electrolyte membrane is dry. And the air volume of the fan 22 corresponding to the said part is increased, and / or the water supply amount of the nozzle 23 is also increased. Thereby, since the temperature of the said part falls rapidly and the humidity of a solid polymer electrolyte membrane rises, the output of the said part increases and a terminal voltage rises.

  When the terminal voltage fluctuates at a low position, the control means determines that the temperature of the portion is low and the generated water is condensed, and reduces the air volume of the fan 22 corresponding to the portion. And / or the water supply amount of the nozzle 23 is also reduced. As a result, the condensed product water evaporates and the clogging is eliminated, so that the output of the portion increases and the terminal voltage rises. When it is determined that the temperature of the portion is low and the generated water is condensed, the air volume of the fan 22 is increased and / or the water supply amount of the nozzle 23 is increased, or ON / OFF is repeated. The condensed product water can be eliminated by giving an impact to the part. As a result, water clogging is eliminated, so that the output of the part increases and the terminal voltage rises.

  As described above, in the present embodiment, a plurality of fans 22 and nozzles 23 are used as cooling means that respectively correspond to a plurality of portions of the fuel cell stack 11 and whose cooling capacity can be adjusted independently of each other. The cooling capacity of the fan 22 and / or the nozzle 23 corresponding to the portion where the temperature of the stack 11 is unevenly distributed is adjusted. Thereby, the temperature of the fuel cell stack 11 can be quickly made uniform, and the output can be increased. Further, the entire system is not enlarged and the system structure is not complicated.

  In addition, this invention is not limited to the said embodiment, It can change variously based on the meaning of this invention, and does not exclude them from the scope of the present invention.

It is a three-plane figure which shows the structure of the fuel cell system in embodiment of this invention. It is a graph which shows the relationship between the performance of a fuel cell in embodiment of this invention, temperature, and humidity. It is a graph which shows the change of the single cell voltage when the performance of the part of fuel cell stack in embodiment of this invention falls.

Explanation of symbols

11 Fuel Cell Stack 21 Temperature Detector 22 Fan 23 Nozzle

Claims (6)

A fuel cell in which an electrolyte layer is sandwiched between a fuel electrode and an oxygen electrode is laminated with a separator having a fuel gas flow path formed along the fuel electrode and an air flow path formed along the oxygen electrode. A fuel cell stack,
A temperature detector for detecting temperatures of a plurality of portions of the fuel cell stack;
A plurality of cooling means respectively corresponding to a plurality of portions of the fuel cell stack and capable of adjusting the cooling capacity independently of each other;
A fuel cell system comprising: control means for adjusting the cooling capacity of the cooling means corresponding to a portion where the temperature of the fuel cell stack is unevenly distributed to equalize the temperature of the fuel cell stack.   The fuel cell system according to claim 1, wherein the cooling means is a fan that supplies air to the air flow path. The cooling means is a nozzle for supplying water to the air flow path;
2. The fuel cell system according to claim 1, wherein the control unit increases a water supply amount of a nozzle corresponding to a portion where the temperature of the fuel cell stack is high, and decreases a water supply amount of a nozzle corresponding to a portion where the temperature is low. A fuel cell in which an electrolyte layer is sandwiched between a fuel electrode and an oxygen electrode is laminated with a separator having a fuel gas flow path formed along the fuel electrode and an air flow path formed along the oxygen electrode. A fuel cell stack,
A voltage detector for detecting terminal voltages of a plurality of portions of the fuel cell stack;
A plurality of cooling means respectively corresponding to a plurality of portions of the fuel cell stack and capable of adjusting the cooling capacity independently of each other;
And a control means for adjusting the cooling capacity of the cooling means corresponding to the portion where the output of the fuel cell stack is unevenly distributed.   5. The fuel cell system according to claim 4, wherein the control unit adjusts a cooling capacity of the cooling unit according to a history of an output change of the fuel cell stack. A temperature detector for detecting the temperature of a plurality of portions of the fuel cell stack;
6. The fuel cell system according to claim 5, wherein the control unit specifies a cause of output decrease in a portion where the output is low from the history of change in output of the fuel cell stack and the temperature, and adjusts the cooling capacity of the cooling unit.

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