JP2005183040A - Method for measuring current distribution of stacked fuel cell, stacked fuel cell, and operation method of stacked fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To observe a power generating state in a fuel cell in order to operate the fuel cell in the optimum state. <P>SOLUTION: The current distribution measuring method of a stacked fuel cell is that a cell stack 1 of the fuel cell is formed by joining an air electrode to one side of an electrolyte and a fuel electrode to the other side, interposing them between separators each having a gas passage to form a cell, stacking the cells, and installing current collecting members 2 taking out electric power in the vertical direction to the stacking thickness direction at the end part, a magnetic sensor 3 is arranged at the end part in the thickness direction the fuel cell cell stack, a magnetic field generating when current flows in the current collecting member 2 is measured with the magnetic sensor 3, and the current distribution of the fuel cell cell stack 1 is measured based on the measured magnetic field. The cause of a drop in power generation capacity is determined from a part where power generation capacity is dropped in the fuel cell cell, and operation restoring the drop in power generation capacity can be conducted. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a stacked fuel cell in which fuel cells that generate electrical energy by an electrochemical reaction between hydrogen and oxygen are stacked.

  Development of fuel cells, particularly polymer electrolyte fuel cells, is being promoted as a power generation system for vehicles or stationary.

  In a fuel cell, the following electrochemical reaction between hydrogen and oxygen occurs, and electric energy is generated.

(Fuel electrode side) H ₂ → 2H ⁺ + 2e ⁻
(Air electrode side) 2H ⁺ + 1 / 2O ₂ + 2e ⁻ → H ₂ O
(Overall) H ₂ + 1 / 2O ₂ → H ₂ O
In a fuel cell, normally, an air electrode is joined to one surface of an electrolyte, and a fuel electrode is joined to the other surface. A fuel cell is formed by sandwiching the electrode with a separator having a gas flow path. Electric power is generated by supplying hydrogen to the fuel electrode. Since a single fuel battery cell cannot provide enough power for practical use, a stacked fuel cell in which a large number of fuel battery cells are stacked provides a high power generation amount. In the stacked fuel cell, many fuel cells are electrically connected in series.

  In the fuel cell, one of the purposes of operation is to obtain the maximum power generation amount by reducing the supply amount of the fuel gas (hydrogen) and air (oxygen) to the fuel cell as much as possible. Further, in the polymer electrolyte fuel cell, since water is used as a proton medium, the fuel gas (hydrogen) supplied to the fuel cell is humidified.

  However, the fuel cell generates water as a result of its reaction. When the moisture is excessive in the fuel cell, there is a problem that an excessive amount of moisture inhibits power generation and power generation is reduced. For this reason, it is required to maintain a proper range of moisture in the fuel cell.

  And the request | requirement of keeping the inside of this fuel cell with the water | moisture content of an appropriate range is also requested | required also in each fuel cell of a laminated | stacked fuel cell. Specifically, even if the temperature, pressure, or humidity of the gas supplied to the fuel cell is adjusted to keep the fuel cell in an appropriate state, each fuel cell constituting the fuel cell is partially appropriate. It may become out of condition. If it deviates from an appropriate condition, the portion cannot perform sufficient power generation, and the portion of the fuel cell that performs power generation is biased. If the portion where power generation is performed is biased, the deterioration of the portion is accelerated, and the life of the entire fuel cell is shortened. Moreover, the voltage which can be taken out will become low. For this reason, it is requested | required also to hold | maintain with the water | moisture content of an appropriate range also in a fuel cell.

  On the other hand, in the stacked fuel cell, the temperature of the cell at the end tends to be lower than that at the central portion, so that moisture generally tends to accumulate, and as a result, the generated power tends to decrease.

As a means for monitoring the state of the fuel cell, a method of measuring the generated voltage of each fuel cell is used. Specifically, this is a method of diagnosing an abnormal state from a decrease in the cell voltage of the fuel cell. In addition, there has been proposed one that diagnoses the excess or deficiency of the reaction gas from the current distribution in the fuel cell and controls the reaction gas flow rate or load current to prevent the destruction of the fuel cell (for example, Patent Document 1). reference). However, with this method, the power generation capability of each fuel cell can be monitored, but it has not been possible to discriminate until a portion where the fuel cell cannot partially generate power is generated.
JP-A-9-259913

  This invention is made | formed in view of the said actual condition, and makes it a subject to provide the method of observing the electric power generation condition in a battery in order to drive | operate a fuel cell in the optimal state.

  As a result of repeated studies by the present inventors to solve the above-mentioned problems, the method for measuring the current distribution of the stacked fuel cell of the present invention, the stacked fuel cell having the current distribution measuring method, and the operation of the stacked fuel cell I found a way.

  The method of measuring the current distribution of the stacked fuel cell according to the present invention comprises a fuel cell comprising an air electrode joined to one surface of an electrolyte and a fuel electrode joined to the other surface and sandwiched by a separator having a gas flow path. A method for measuring the current distribution of a stacked fuel cell having a fuel cell stack in which a current collecting member for stacking and collecting power in a direction perpendicular to the thickness direction stacked at an end thereof is provided, A magnetic sensor is arranged at the end of the cell stack in the thickness direction, the magnetic field generated when electricity flows through the current collector is measured by the magnetic sensor, and the current distribution of the fuel cell stack is measured from the measured magnetic field. Is measured.

  The current distribution measuring method of the present invention measures the current distribution of the fuel cell stack by measuring the magnetic field generated by the current flowing through the end of the fuel cell with a magnetic sensor.

  The laminated fuel cell according to the present invention comprises a fuel cell unit in which an air electrode is joined to one surface of an electrolyte and a fuel electrode is joined to the other surface, and sandwiched by a separator having a gas flow path. A fuel cell stack having a current collecting member for extracting power in a direction perpendicular to the thickness direction stacked on the fuel cell, and a magnetic sensor disposed at an end of the fuel cell stack. And

  In the stacked fuel cell of the present invention, the magnetic sensor disposed at the end of the fuel cell stack can measure the current distribution of the current generated by the power generation in the fuel cell stack. And it becomes possible to adjust an operating condition so that it may become an optimal electric power generation state from the measured electric current distribution.

  The operation method of the current distribution of the stacked fuel cell according to the present invention includes a fuel cell in which an air electrode is joined to one surface of an electrolyte and a fuel electrode is joined to the other surface and sandwiched by a separator having a gas flow path. A fuel cell stack in which a current collecting member for stacking and collecting power in a direction perpendicular to the thickness direction stacked on the end of the stack is disposed; and a magnetic sensor disposed on an end of the fuel cell stack; A method for operating a stacked fuel cell, wherein a current distribution in a fuel cell is calculated from a magnetic field generated by a current flowing through a current collecting member measured by a magnetic sensor. Control of the gas supplied to the cell stack is performed.

  In the operation method of the present invention, the magnetic sensor disposed at the end of the fuel cell stack measures the current distribution of the current generated by the power generation in the fuel cell stack, and the optimum current is measured from the measured current distribution. By controlling the gas supplied to the fuel cell stack so as to be in a power generation state, the stacked fuel cell can be operated in an optimal operating condition.

  The method for measuring the current distribution of a stacked fuel cell according to the present invention measures a magnetic field generated by a current flowing through a current collecting member disposed at an end of a fuel cell stack, and the fuel cell from the measured magnetic field. Obtain the current distribution of the laminate. Then, from the current distribution of the fuel cell stack, it is possible to determine a portion where the power generation capability is reduced in the fuel cell, and to determine the cause of the decrease in the power generation capability.

  The stacked fuel cell of the present invention is a fuel cell that can carry out the above current distribution measurement method, and can determine the cause of the decrease in the power generation capability, thereby addressing the cause of the decrease in the power generation capability. This is a fuel cell capable of suppressing a decrease in power generation capacity.

  The operation method of the stacked fuel cell according to the present invention is the above-described operation method of the fuel cell, wherein a current distribution flowing through the fuel cell stack is obtained by a magnetic sensor, and the fuel cell stack is generated when the current distribution is affected. It is an operation method that keeps the inside of the fuel cell cell under optimum conditions by adjusting the gas supplied to the body and suppresses the decrease in power generation capacity.

(Measurement method of current distribution of stacked fuel cell)
The current distribution measuring method according to the present invention comprises stacking fuel cells in which an air electrode is joined to one surface of an electrolyte and a fuel electrode is joined to the other surface and sandwiched by a separator having a gas flow path. This is a method for measuring the current distribution of a stacked fuel cell having a fuel cell stack in which a current collecting member for taking out electric power in a direction perpendicular to the thickness direction stacked on the part is disposed.

  In the current distribution measuring method of the present invention, a magnetic sensor is disposed at the end of the fuel cell stack in the thickness direction, and the magnetic field generated when electricity flows through the current collector is measured by the magnetic sensor. The current distribution of the fuel cell stack is measured from the applied magnetic field.

In general, when a current i (A) flows through a lead wire having an infinite length, a magnetic flux density B (Wb / m) having a magnitude expressed by the formula 1 is obtained at a point where the distance from the lead wire is r (m). ² ) is known to occur (right-hand rule).

  The current distribution measuring method of the present invention measures the magnetic field of the fuel cell stack, with the current collecting member disposed at the end of the fuel cell stack being regarded as this conducting wire. The fuel cell stack takes out the electric power generated in each fuel cell through the current collecting member to the outside of the battery. The electric power generated in the power generation region of the fuel cell flows in the thickness direction in the fuel cell stack. Then, electricity is collected by the current collecting member, and a current flows in the direction in which the current collecting member extends (direction perpendicular to the thickness direction of the fuel cell stack). The current flowing through the current collecting member at a position corresponding to the power generation region of the fuel battery cell increases as it proceeds to the downstream portion in the current flowing direction. When the direction in which the current collected in the current collecting member flows is considered as the length direction of the conducting wire, a magnetic field is generated in the circumferential direction in the cross section perpendicular to the direction in which the current collecting member extends. At this time, the current distribution measuring method of the present invention obtains the current distribution of the fuel cell stack from the change of the magnetic field.

  The magnetic permeability of the stacked fuel cell (and fuel cell) and the objects around the stacked fuel cell is the same as that of air, and the current distribution measuring method of the present invention will be specifically described with reference to FIGS. To do.

  It is assumed that the fuel cell and its power generation possible region are formed in a rectangular shape. Here, the power generation possible region indicates a region where an electrochemical reaction proceeds in a fuel cell, and in an actual fuel cell, gas is supplied in a state where an air electrode, an electrolyte, and a fuel electrode are stacked. It is an area.

  The current collector plate 2 of the fuel cell stack 1 in which such fuel cells are stacked is integrally provided on the current collector main body 20 and the current collector main body 20 that substantially match the outer peripheral shape of the fuel cell. And a terminal portion 21 protruding from the outer periphery of the short side of the fuel cell stack 1.

  When power generation is performed in the fuel cell stack 1, a current flows in the thickness direction of the fuel cell stack 1 (FIG. 1). The current flowing in the thickness direction reaches the current collector body 20 of the current collector plate 2. In the current collector body 20 of the current collector plate 2, a current flows toward the terminal portion 21. The current flowing through the current collector main body 20 increases as it approaches the terminal portion 21 (FIG. 2). 2 (~ 5), the magnitude of the current flowing through the current collector plate 2 is indicated by the thickness of the arrow. In the region farthest from the terminal portion 21 of the current collecting main body portion 20, a current generated in a portion corresponding to the position of the fuel cell flows, and this current flows (indicated by an arrow aligned at the right end in FIG. 2). Indicated current).

  And in the area | region which approached the terminal part 21 slightly from the position most distant from the terminal part 21 of the current collection main body part 20, in the fuel cell corresponding to the position furthest from the terminal part 21 of the current collection main body part 20 A current (current indicated by an arrow at the right end in FIG. 2) that is generated and flows through the current collector main body 20 toward the terminal portion 21 and generated in the portion of the fuel cell corresponding to this region (fuel cell) A current that is the sum of the current flowing from the laminate 1 and the current (current indicated by an arrow in the second column from the right in FIG. 2) flows. As described above, the closer to the terminal portion 21, the larger the current flowing in the current collector body portion 20.

  Here, assuming that each fuel cell of the fuel cell stack 1 performs uniform power generation in the power generation possible region, the magnitude of the current flowing through the current collector body 20 of the current collector plate 2 is as shown in FIG. As shown, if the distance from the terminal portion 21 is the same position, the distance is almost the same. As shown in FIG. 2, since the terminal portion 21 is narrower than the current collecting main body portion 20 (the vertical width in FIG. 2), the current flowing in the vicinity of the terminal portion 21 of the current collecting main body portion 20 is The direction is toward the terminal portion 21.

  At this time, when the current shown in FIG. 2 flows through the current collector plate 2, a magnetic field is generated around the current collector plate 2 as shown in FIG. Specifically, a magnetic field having a circumferential magnetic field line is generated in a cross section perpendicular to the protruding direction of the terminal portion 21 of the current collector plate 2. When each fuel cell of the fuel cell 1 performs uniform power generation in the power generation possible region, the magnetic flux density of the magnetic field generated around the current collector plate 2 decreases in proportion to the distance from the terminal portion 21. The current density measuring method of the present invention measures this magnetic field with a magnetic sensor.

  In the fuel cell stack 1, it is assumed that power generation is stopped in a part of the power generation possible region of the fuel cell (a position corresponding to the region A in FIG. 4). When the power generation is stopped, no current flows into the area A of the current collecting main body. When the current stops flowing into the region A, in the region adjacent to the region A and closer to the terminal portion 21 than the region A (region B in FIG. 4), the fuel cell is connected to the current collector main body 20 in the region B. Only the current flowing from the cell stack 1 will flow. When power generation does not stop in a part of the fuel cell, the sum of the current collected in the current collector body in the region A and the current collected in the current collector plate body from the fuel cell in the region B Current flows in the region B.

  That is, when a region where power generation is stopped occurs in a part of the fuel battery cell, the current flowing through the current collector body 20 corresponding to this region changes. Furthermore, the current flowing through the region on the terminal part 21 side of the current collector main body 20 corresponding to the region where power generation is stopped changes. When the current flowing through the current collector body 20 changes, the magnetic field generated in the current collector plate 2 also changes. Specifically, in the current collector plate 2 shown in FIG. 4, a magnetic field is generated by a current flowing in a region except the region A as shown in FIG. Further, the magnetic flux density of the magnetic field in the cross section including the region B in FIG. 5 is smaller than the magnetic flux density of the magnetic field in the same cross section in FIG. This is because the current in the region B in FIG. 5 is lower than that in the same region in FIG.

  And the electric power generation condition of the fuel cell laminated body 1 can be judged by measuring the magnetic field which generate | occur | produced in each current collecting plate 2 of FIG. 3 and FIG. 5 with a magnetic sensor. Moreover, the area | region where the power generation capability stopped in the fuel cell laminated body 1 can be determined depending on the measurement position of the magnetic field. That is, by measuring the magnetic field generated in the current collecting member of the fuel cell stack 1, it is possible to determine the region where the current density of the fuel cell stack is reduced.

  The current distribution measuring method of the present invention measures a magnetic field generated in a current collecting member with a magnetic sensor, and by this measurement, it is possible to determine a region where power generation is stopped or power generation capacity is reduced. Thereby, the current distribution of the fuel cell stack can be obtained.

  The current distribution measuring method of the present invention measures the magnetic field generated in the circumferential direction of the cross section perpendicular to the direction in which the current flows in the current collecting member, so that the magnetic sensor is in the thickness direction of the fuel cell stack. Arranged at the end.

  The current collecting member is preferably formed of a current collecting plate, and the magnetic sensor preferably measures the magnetic field of the current collecting plate. When the current collecting member is made of a plate-shaped current collecting plate, the current collecting member can be laminated in the same manner as the fuel battery cell, and the formation of the fuel battery cell laminate is facilitated. The current collector plate has a uniform thickness (in the thickness direction of the fuel cell stack), and the current flowing through the current collector plate is uniform in a cross section perpendicular to the current flow direction.

  A plurality of magnetic sensors are preferably provided. Normally, an error of about ± 0.3 G occurs due to geomagnetism, but by providing a plurality of magnetic sensors, the geomagnetism can be corrected, and more accurate measurement can be performed. That is, by providing a plurality of magnetic sensors, a more accurate current distribution can be obtained from data obtained by each magnetic sensor.

(Stacked fuel cell)
The stacked fuel cell of the present invention includes a fuel cell stack and a magnetic sensor.

  A fuel cell stack is formed by stacking fuel cells in which an air electrode is joined to one surface of an electrolyte and a fuel electrode is joined to the other surface, and sandwiched by a separator having a gas flow path. A current collecting member for taking out electric power in a direction perpendicular to the thickness direction is provided. The magnetic sensor is disposed at the end of the fuel cell stack. The stacked fuel cell of the present invention is a fuel cell to which the current distribution measuring method can be applied.

  The current collecting member is preferably formed of a current collecting plate, and the magnetic sensor preferably measures the magnetic field of the current collecting plate. When the current collecting member is made of a plate-shaped current collecting plate, the current collecting member can be laminated in the same manner as the fuel battery cell, and the formation of the fuel battery cell laminate is facilitated. The current collector plate has a uniform thickness (in the thickness direction of the fuel cell stack), and the current flowing through the current collector plate is uniform in a cross section perpendicular to the current flow direction.

  The place where the magnetic sensor is disposed is not particularly limited as long as it is a position where the magnetic field generated in the current collecting member can be measured. For example, you may arrange | position in the state contact | abutted to the surface facing the fuel cell of the current collection member, or the current collection member. More preferably, the magnetic sensor is disposed in contact with the current collecting member.

A plurality of magnetic sensors are preferably provided. Normally, an error of about ± 0.3 × 10 ⁻⁴ T (0.3 G) occurs due to geomagnetism, but the geomagnetism can be corrected by providing a plurality of magnetic sensors, and the accuracy is higher. Measurements can be made. That is, by providing a plurality of magnetic sensors, a more accurate current distribution can be obtained from data obtained by each magnetic sensor.

  The larger the number of magnetic sensors, the more effective the identification of the region where the power generation capacity is reduced.

A magnetic sensor will not be specifically limited if it is a sensor which can measure the magnetic field in the place arrange | positioned. Here, a fuel cell of a general polymer electrolyte, in the fuel cell of the current density of the area of the power generation area is 400cm ^2, 1A / cm ^2, the maximum value of the magnetic flux density is ± 6 × 10 ^-4 T Since it is about (6G), a magnetic sensor such as a Hall element, a magnetoresistive element, or a fluxgate sensor can be used. Of these elements, an element capable of measuring the magnetic flux density in a plane perpendicular to the thickness direction is more preferable as a magnetic sensor.

  The stacked fuel cell of the present invention preferably has a calculation means for calculating the current distribution from the measured value of the magnetic sensor. By having the computing means, it is possible to calculate the current distribution from the measured value of the magnetic sensor. Moreover, it is preferable that this calculating means determines the optimal operating condition of a laminated | stacked fuel cell from the electric current distribution of a fuel cell laminated body.

  The stacked fuel cell of the present invention preferably has gas control means for controlling the gas flow rate and / or humidity of the gas supplied to the air electrode and / or the fuel electrode. By having the gas control means, the gas supplied to the air electrode and / or the fuel electrode is adjusted, and a decrease in power generation performance in the fuel cell can be suppressed.

  Furthermore, the gas control means is preferably connected to the calculation means. By connecting the gas control means and the calculation means, it is possible to determine the operating conditions of the stacked fuel cell from the current distribution, and it is possible to perform power generation according to the operating conditions.

  The stacked fuel cell of the present invention can have the same configuration as a conventionally known stacked fuel cell except that a magnetic sensor is disposed at the end of the fuel cell stack. The type of the stacked fuel cell of the present invention is not limited as long as the fuel cells are stacked, but is preferably a solid polymer fuel cell.

  One embodiment of the stacked fuel cell of the present invention is shown in FIG. 1 and FIGS. The laminated fuel cell shown below shows one form of the fuel cell of the present invention, and does not limit the present invention.

  FIG. 6 is a cross-sectional view of the fuel cell 6. The fuel cell 6 includes an MEA (Membrane Electrode Assembly) in which electrodes 61 and 62 are disposed on both side surfaces of the electrolyte membrane 60, and an air-side separator 63 and a fuel-side separator 64 that sandwich the MEA. Here, the air-side separator 63 and the fuel-side separator 64 are made of a conductive material and also serve as current collector plates for the respective electrodes. In this fuel cell, the fuel side separator 64 also serves as a negative electrode current collector plate, and the air side separator 63 also serves as a positive electrode current collector plate. FIG. 6 is a diagram schematically showing the configuration of the fuel battery cell 6, and the air-side separator 63 and the fuel-side separator 64 are actually much thicker than the electrolyte membrane 60. Specifically, the separators 63 and 64 have a thickness of about 1 to 2 mm, and the MEA has a total of about 0.5 mm of the electrolyte membrane, the diffusion layer, and the catalyst. The electrodes 61 and 62 also indicate diffusion layers. This diffusion layer usually has a thickness of about 0.2 mm.

  FIG. 7 is a view showing the air-side separator 63, and the air-side separator 63 is connected to the air circulation hole 630 that forms an air introduction passage for introducing air into the power generation region when stacked. An air inlet portion 631, an air outlet hole 634 that forms an air outlet passage for discharging air from the power generation region when stacked, an air outlet portion 633 connected to the air outlet hole 634, and an air outlet portion 633. And an air flow path groove 632 for flowing air from the air inlet portion 631 toward the air outlet portion 633. Further, the air-side separator 63 is formed with a hydrogen circulation hole 635 that forms a hydrogen introduction channel when stacked and a hydrogen discharge hole 636 that forms a hydrogen discharge channel.

  FIG. 8 is a view showing the fuel-side separator 64, and the fuel-side separator 64 is connected to the hydrogen circulation hole 640 that forms a hydrogen introduction channel for introducing hydrogen into the power generation region when stacked, and the hydrogen circulation hole 640. A hydrogen inlet port 641, a hydrogen outlet hole 644 forming a hydrogen outlet channel for discharging hydrogen from the power generation region when stacked, a hydrogen outlet portion 643 connected to the hydrogen outlet hole 644, and a hydrogen outlet portion 643 And a hydrogen channel groove 642 for flowing hydrogen from the hydrogen inlet portion 641 toward the hydrogen outlet portion 643. In addition, the fuel separator 64 is formed with an air circulation hole 645 that forms an air introduction passage when stacked, and an air discharge hole 646 that forms an air discharge passage.

  The air-side separator 63 and the fuel-side separator 64 are provided with cooling flow path holes 637 and 647 that define a coolant flow path through which the coolant flows when stacked.

  Then, the fuel cell stack 1 is formed by laminating about 50 layers of the fuel cell 6 with the air-side separator 63 and the fuel-side separator 64 facing away from each other. At this time, an air introduction channel, an air discharge channel, a hydrogen introduction channel, a hydrogen discharge channel, and a coolant channel are provided in the thickness direction of the fuel cell stack 1. Note that the air-side separator 63 and the fuel-side separator 64 are preferably integrated.

  At both ends of the fuel cell stack 1, current collector plates 2 are formed by cutting a metal plate into a predetermined shape. The current collector plate 2 includes a current collector body 20 having an outer peripheral shape that substantially matches the outer peripheral shape of the fuel cell 6, and a terminal that is provided integrally with the current collector body 20 and protrudes from the outer periphery of the fuel cell stack 1. Part 21.

  In addition, the fuel cell stack 1 is pressurized in the thickness direction in order to ensure airtightness and improve the adhesion of the fuel cells 3. This pressurization was performed by pressing in the thickness direction of the fuel cell stack 1 with the pressurizing plate 5 through the insulating plate 4.

  The insulating plate 4 is made of a glass epoxy resin having the same shape as that of the current collector body 20, and a plurality of magnetic sensors 3 are embedded therein. Further, the magnetic sensor 3 was in contact with the current collector plate 2 when the insulating plate 4 was disposed.

  Then, each of the air introduction flow path, the air discharge flow path, the hydrogen introduction flow path, the hydrogen discharge flow path, and the coolant flow path of the fuel cell stack 1 in which the magnetic sensor 3 is disposed is connected to the air introduction means 7A. , Air discharge means 7B, hydrogen introduction means 8A, hydrogen discharge means 8B, coolant introduction means (not shown) and coolant discharge means (not shown). Each of these means has a flow rate adjusting means for adjusting the flow rate and a moisture content adjusting means for adjusting the moisture content in the gas.

  Then, the magnetic sensor 3 was connected to the calculation means 9. The arithmetic means 9 is connected to the flow rate adjusting means and the moisture amount adjusting means of each means 7A, 7B, 8A, 8B, and instructs to adjust the flow rate in the flow rate adjusting means and the moisture content of the gas in the moisture amount adjusting means. To do. That is, the calculation means 9 obtains the current distribution of the fuel cell stack 1 from the magnetic field measured by the magnetic sensor 2, and determines the cause when the current distribution is caused by a decrease in power generation capacity or the like, The gas to the fuel cell stack is adjusted so as to eliminate the current distribution.

  The structure of this stacked fuel cell is shown in FIG.

  Since the stacked fuel cell of the present invention measures the magnetic field of the fuel cell stack with a magnetic sensor, the structural material for constituting the entire fuel cell has a low magnetic field (magnetic flux density distribution). It is preferable to use a material having magnetic permeability. As such a material, it is preferable to use austenitic stainless steel. When using austenitic stainless steel, it is preferable to suppress an increase in magnetic permeability due to cold working by a process such as magnetic annealing.

(Operation method of stacked fuel cell)
The operation method of the current distribution of the stacked fuel cell according to the present invention includes a fuel cell in which an air electrode is joined to one surface of an electrolyte and a fuel electrode is joined to the other surface and sandwiched by a separator having a gas flow path. A fuel cell stack in which a current collecting member for stacking and collecting power in a direction perpendicular to the thickness direction stacked on the end of the stack is disposed; and a magnetic sensor disposed on an end of the fuel cell stack; A method for operating a stacked fuel cell, wherein a current distribution in a fuel cell is calculated from a magnetic field generated by a current flowing through a current collecting member measured by a magnetic sensor. The gas supplied to the cell stack is controlled.

  The operation method of the present invention is an operation method capable of generating power without causing a partial decrease in power generation capacity of the fuel cell in the stacked fuel cell.

  In a fuel cell, an air electrode is joined to one surface of an electrolyte, and a fuel electrode is joined to the other surface, and this is sandwiched by a separator having a gas flow path. Hydrogen is supplied to the electrode, and electric energy is generated by an electrochemical reaction between hydrogen and oxygen. For this reason, the power generation capacity can be adjusted by adjusting the supply status of air and hydrogen supplied to the fuel cells.

  The operation method of the present invention obtains a portion where the power generation capacity of the fuel cell is reduced from the current distribution of the current collecting member of the fuel cell stack, determines the cause of the decrease in the power generation capacity, The gas to be supplied is controlled. By controlling this gas, it is possible to eliminate a decrease in power generation capacity.

  A fuel cell supplies air to the air electrode and hydrogen to the fuel electrode to extract electric power from the electrochemical reaction between oxygen and hydrogen. In solid polymer fuel cells, water is used as the proton medium. Therefore, the gas (hydrogen) supplied to the fuel cell is humidified. However, when the moisture is excessive in the fuel cell, an excessive amount of moisture inhibits power generation and the generated power is reduced.

  That is, it is considered that a partial decrease in power generation capacity in the fuel cell is caused by moisture. Further, this partial decrease in power generation capacity occurs at the hydrogen inlet where humidified hydrogen is introduced on the fuel electrode side, and at the air outlet where water generated by the power generation reaction collects on the air electrode side. It has become easier.

  For this reason, from the current distribution of the fuel cell stack, when a part of the power generation capacity is reduced, the lowered position is known. That is, the cause of the decrease in power generation capacity can be determined. And the fall of a power generation capability can be eliminated by adjusting the gas supplied to a fuel cell laminated body so that this fall of a power generation capability may be eliminated.

  In the operation method of the stacked fuel cell of the present invention, it is preferable that the magnetic sensor is disposed at a substantially central portion in the thickness direction of the fuel cell stack.

  In the operation method of the stacked fuel cell of the present invention, it is preferable that a plurality of magnetic sensors are provided.

  One embodiment of the operation method of the stacked fuel cell of the present invention will be described below. In addition, this description is demonstrated using the laminated | stacked fuel cell shown in the said FIG. 1 and FIGS.

  First, in the stacked fuel cell, power is generated by introducing air into the air electrode 61 of the fuel battery cell 6 and humidified hydrogen into the fuel electrode 62. When appropriate power generation is performed on the entire surface of the power generation region, the current distribution of the current flowing in the thickness direction of the fuel cell stack 1 is not affected.

  Humidified hydrogen (water-containing hydrogen gas) is introduced into the fuel electrode 62 through a hydrogen introduction channel. Since the moisture contained in the hydrogen acts as a proton medium, the moisture is consumed as the proton medium as the hydrogen travels through the hydrogen flow channel 642 partitioned by the fuel-side separator 64. For this reason, the moisture concentration in the hydrogen flowing through the hydrogen flow channel groove 642 decreases as the process proceeds from the vicinity of the hydrogen inlet 641 toward the hydrogen outlet 643.

  Here, it is assumed that the amount of water in the hydrogen introduced into the fuel electrode 62 has increased. The amount of water in the hydrogen in the vicinity of the hydrogen inlet 641 of the hydrogen flow channel 642 increases. If the amount of water in hydrogen becomes excessive, the water hinders the progress of the electrochemical reaction for power generation in the vicinity of the hydrogen inlet 641 of the hydrogen flow channel 642, and the power generation capacity in this portion decreases. This reduction in the power generation capacity is caused by the amount of power generated in the power generation region of the fuel cell 6. Then, the current flowing from the fuel cell stack 1 is reduced in the region corresponding to the portion where the power generation amount of the current collector main body 20 of the current collector plate 2 is reduced. The amount of current flowing in this region of the current collector main body 20 and the region between this region and the terminal portion 21 is also reduced. That is, there is a difference in the distribution of current flowing through the current collector plate 2. The magnetic field generated by this current distribution is measured by the magnetic sensor 3. Then, measurement data is sent from the magnetic sensor 2 to the calculation means 9, and the calculation means 9 calculates the generation and position of the current distribution. Then, the calculation means 9 determines that the power generation capacity has decreased due to the excessive amount of water in the hydrogen from the generation position based on the current distribution, and supplies the fuel to the hydrogen introduction means 8A and the hydrogen discharge means 8B. An instruction is given to reduce the amount of water in the hydrogen introduced into the battery cell 6 (set to an appropriate amount of water). In accordance with an instruction from the calculation means 9, the flow rate adjustment means and the water content adjustment means are adjusted so that the water content in hydrogen becomes an appropriate amount (reduced). As a result, the amount of water in the hydrogen in the vicinity of the hydrogen inlet 641 of the hydrogen channel groove 642 is reduced, and the water does not hinder the progress of the electrochemical reaction for power generation, and is uniform in the power generation region of the fuel cell 6. Power generation will be performed.

  Insufficient water content in hydrogen can be determined from the power generated by the stacked fuel cell and the water content in the hydrogen discharged to the hydrogen discharging means 8B.

Further, the water generated by the electrochemical reaction for power generation at the air electrode 61 is reversely diffused in the electrolyte 60 and reaches the fuel electrode 63 side, and H ⁺ ions are drawn to the air electrode 61 in a proton state. . That is, in the vicinity of the air outlet 633, a decrease in power generation capacity due to the back-diffused moisture is likely to occur.

  When the moisture permeated through the electrolyte 60 increases, the amount of moisture in the air flow channel groove 632 increases. When the amount of water in the air flow channel groove 632 becomes excessive, the water moves to the fuel electrode 64 side by reverse osmosis, and an electrochemical reaction for power generation near the air outlet 633 of the air flow channel groove 632 occurs. Moisture inhibits the progress, and the power generation capacity in this part decreases. This decrease in the power generation capacity causes the current distribution of the fuel cell stack 1 and further causes the current distribution flowing through the current collector plate 2. The magnetic field generated by this current distribution is measured by the magnetic sensor 3. Then, measurement data is sent from the magnetic sensor 2 to the calculation means 9, and the calculation means 9 calculates the current distribution and its generation position. Then, it is determined from the generation position based on the current distribution that the power generation capacity has decreased due to an excessive amount of water in the air flow channel groove 632, and the fuel cell is connected to the air introduction means 7 A and the air discharge means 7 B. 6 is instructed to reduce the amount of moisture in the air introduced to an appropriate amount of water, and the respective flow rate adjusting means and moisture amount adjusting means set the appropriate amount of water. At this time, the hydrogen insertion means 8A and the hydrogen discharge means 8B may be simultaneously instructed to adjust the amount of water in the hydrogen. As a result, a decrease in power generation capacity due to an excessive amount of moisture in the air can be suppressed, and an optimal power generation state of the stacked fuel cell can be maintained.

  As described above, the current distribution of the current collector plate 2 is measured by the magnetic sensor 2 disposed at the end portion of the fuel cell stack 1, and the gas supplied to the fuel cell stack 1 from the current distribution ( By adjusting the air or hydrogen), the stacked fuel cell was maintained in an optimal operating condition. When the stacked fuel cell is operated in an optimal operating condition, it was possible to generate power while maintaining high power generation.

It is the figure which showed the flow of the electric current of a fuel cell laminated body. It is the figure which showed the electric current which flows through the current collection slope. It is the figure which showed the state which the magnetic field generate | occur | produced on the current collecting plate. It is the figure which showed the electric current which flows into the collector plate of the fuel cell laminated body which has a power generation stop area | region in part. It is the figure which showed the state which the magnetic field generate | occur | produced in the current collection board of the fuel cell laminated body which has a power generation stop area | region in part. It is sectional drawing of a fuel battery cell. It is the figure which showed the air side separator. It is the figure which showed the fuel side separator. It is the figure which showed the structure of the laminated fuel cell.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel cell laminated body 2 ... Current collecting plate 3 ... Magnetic sensor 4 ... Insulating plate 5 ... Pressure plate 6 ... Fuel cell 60 ... Electrolyte 61 ... Air electrode 62 ... Fuel electrode 63 ... Air side separator 64 ... Fuel side separator 630 ... Air circulation hole 631 ... Air inlet part 632 ... Air channel groove 633 ... Air outlet part 634 ... Air outlet hole 635 ... Hydrogen outlet hole 636 ... Hydrogen outlet hole 637 ... Cooling channel hole 640 ... Hydrogen passage hole 641 ... Hydrogen Inlet part 642 ... Hydrogen flow path groove 643 ... Hydrogen outlet part 644 ... Hydrogen discharge hole 645 ... Air flow hole 646 ... Air discharge hole 647 ... Cooling flow path hole 7A ... Air introduction means 7B ... Air discharge means 8A ... Hydrogen introduction means 8B ... Hydrogen discharge means 9 ... Calculation means

Claims (11)

An air electrode is joined to one surface of the electrolyte, and a fuel electrode is joined to the other surface, and fuel cells sandwiched between them by a separator having a gas flow path are stacked, and perpendicular to the thickness direction stacked at the end. A method for measuring the current distribution of a stacked fuel cell having a fuel cell stack in which a current collecting member for extracting electric power in a direction is provided,
A magnetic sensor is disposed at the end of the fuel cell stack in the thickness direction, and a magnetic field generated when electricity flows through the current collecting member is measured by the magnetic sensor, and the fuel is measured from the measured magnetic field. A method for measuring a current distribution of a stacked fuel cell, comprising measuring a current distribution of a battery cell stack. The current collecting member is formed by a current collecting plate;
The method of measuring a current distribution of a stacked fuel cell according to claim 1, wherein the magnetic sensor measures a magnetic field of the current collector plate.   The method of measuring a current distribution of a stacked fuel cell according to claim 1, wherein a plurality of the magnetic sensors are provided. An air electrode is joined to one surface of the electrolyte, and a fuel electrode is joined to the other surface, and fuel cells sandwiched between them by a separator having a gas flow path are stacked, and perpendicular to the thickness direction stacked at the end. A fuel cell stack having a current collecting member for extracting electric power in the direction;
A magnetic sensor disposed at an end of the fuel cell stack;
A stacked fuel cell comprising: The current collecting member is formed by a current collecting plate;
The stacked fuel cell according to claim 4, wherein the magnetic sensor measures a magnetic field of the current collector plate.   The stacked fuel cell according to claim 4, wherein a plurality of the magnetic sensors are disposed.   The stacked fuel cell according to claim 4, further comprising calculation means for calculating a current distribution from a measurement value of the magnetic sensor. An air electrode is joined to one surface of the electrolyte, and a fuel electrode is joined to the other surface, and fuel cells sandwiched between them by a separator having a gas flow path are stacked, and perpendicular to the thickness direction stacked at the end. A stacked fuel cell for operating a stacked fuel cell having a fuel cell stack having a current collecting member for extracting electric power in a direction and a magnetic sensor disposed at an end of the fuel cell stack Driving method,
A current distribution in the fuel cell is calculated from a magnetic field generated by a current flowing through the current collecting member measured by the magnetic sensor, and a gas supplied to the fuel cell stack is controlled. Operation method of stacked fuel cell. The current collecting member is formed by a current collecting plate;
The method of operating a stacked fuel cell according to claim 8, wherein the magnetic sensor measures a magnetic field of the current collector plate.   The operation method of the stacked fuel cell according to claim 8, wherein a plurality of the magnetic sensors are provided.   The operation method of the stacked fuel cell according to claim 8, wherein the gas is controlled by controlling a gas flow rate and / or humidity of the gas supplied to the air electrode and / or the fuel electrode.

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