JP2010182488A - Fuel cell and fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell and a fuel cell system that efficiently discharge water adhered to a separator and also ice adhered to the separator due to freezing to the outside, and that improve the efficiency of power generation. <P>SOLUTION: The fuel cell 20 includes an MEA 220 and separators 230 and 240 which are arranged on both sides of the MEA 220, respectively. The separator 240 has a fluid passage part which has grooves 241, in which fluid flows and has inner walls of the grooves 241 which get a water repellent treatment applied, an air supply manifold 242, a cooling medium inlet manifold 243, a hydrogen gas outlet manifold 244, a hydrogen gas inlet manifold 245, a cooling medium outlet manifold 246, an air outlet manifold 247, an air introduction part 248, and an air exhaust part 249 formed. The air introduction part 248 and the air exhaust part 249 have higher water repellency than the inner walls of the grooves 241. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to improvements in fuel cells and fuel cell systems.

  Conventionally, in a fuel cell system, when the fuel cell is started in a low temperature environment, water remaining in the fuel cell and piping connected to the fuel cell is frozen, and gas flow in the fuel cell or in the piping is inhibited, It becomes difficult to start the fuel cell system, for example, power generation stops. In particular, it is known that the gas introduction part has a small cross-sectional area with respect to the gas flow path part, and thus is easily clogged with frozen water (ice).

  In view of this, a fuel cell has been introduced in which water repellent treatment is applied to the gas flow groove portion of the separator to prevent water from adhering to this portion. (For example, refer to Patent Document 1). In addition, a fuel cell having enhanced water repellency in the vicinity of the manifold of the separator (from the gas inlet to the inlet of the gas channel and from the outlet of the gas channel to the gas outlet) has been introduced. (For example, refer to Patent Document 2).

  In addition, when the fuel cell is started at a low temperature, a voltage application process for generating oxygen at the fuel electrode and hydrogen at the oxidant electrode by applying a voltage with the fuel electrode of each single cell as the positive electrode and the oxidant electrode as the negative electrode A fuel cell system is introduced in which the generated hydrogen and oxygen and the power generation process using the oxygen supplied to the oxidizer electrode and the hydrogen supplied to the fuel electrode are repeatedly performed to de-ice the fuel cell stack. ing. (For example, refer to Patent Document 3).

  In addition, the fuel that suppresses freezing in the fuel cell system at the low temperature start-up by continuously increasing the sweep current value until the temperature in the fuel cell system becomes equal to or higher than the predetermined temperature at the low temperature start-up of the fuel cell. Battery systems are also introduced. (For example, refer to Patent Document 4).

  Furthermore, provided in a conduit for discharging the anode gas of the fuel cell, and provided in the conduit, a first flow means for discharging the anode gas at a first flow rate that causes a pressure fluctuation inside the fuel cell, A second flow means for discharging the anode gas at a second flow rate lower than the flow rate of 1, and a switching means for switching between the first flow means and the second flow means, and is discharged from the first flow means. A fuel cell system has also been introduced in which the liquid impurities remaining inside the fuel cell are discharged by the anode gas and then switched to the second circulation means. (For example, refer to Patent Document 5).

  In addition, a fuel cell in which a composite plating layer containing a water repellent material and a metal is formed on a surface portion of a metal plate constituting a separator has been introduced. (For example, refer to Patent Document 6).

JP 2000-36309 A JP 2007-141695 A JP 2003-197241 A JP 2007-42566 A JP 2008-78101 A JP 2000-1000045 A

  However, the fuel cell described in Patent Document 1 has a structure in which only the groove for gas circulation of the separator is subjected to water repellent treatment, and water adheres to the gas introduction part, which is the part that most wants to exclude water. Could not be suppressed. Therefore, when the fuel cell is started in a low temperature environment, the water remaining in the gas introduction part may freeze and block this part, thereby hindering power generation. In addition, when the entire surface of the separator is subjected to water repellent treatment, water generally stays in the gas introduction part located at the lower part of the fuel cell.

  Moreover, since the fuel cell described in Patent Document 2 has no strong or weak water repellency in the vicinity of the manifold, there is a possibility that water may stay in the gas introduction part. In addition, since the water repellency in the power generation surface of the separator is strong and weak, the power generation is also strong and difficult to perform optimal power generation.

  In addition, the fuel cell system described in Patent Document 3 needs to apply a reverse voltage in order to perform electrolysis, but in a fuel cell having a structure in which a plurality of single cells are stacked, It is difficult to apply a voltage evenly across the cells.

  Patent Document 4 does not mention positively discharging generated water for the purpose of suppressing freezing. Furthermore, Patent Document 5 does not mention suppression of freezing that occurs when the fuel cell is started in a low temperature environment, and does not mention discharge of cathode gas.

  Further, the fuel cell described in Patent Document 6 uses a material obtained by mixing a water-repellent material having no electrical conductivity and a metal having hydrophilicity as the composite plating layer. The electrical conductivity at the contact point with the separator becomes insufficient. Moreover, the water repellency of the gas flow path part formed in the metal separator is insufficient.

  The present invention has been made in view of such circumstances, and not only water adhering to the separator but also ice adhering to the separator due to freezing can be efficiently discharged to the outside, and power generation efficiency is improved. An object of the present invention is to provide a fuel cell and a fuel cell system.

  To achieve this object, the present invention provides a fuel cell comprising a plurality of unit cells each including a membrane-electrode assembly and separators disposed on both sides of the membrane-electrode assembly, A fluid passage portion having a groove portion through which water repellent treatment is applied to the inner wall surface of the groove portion, a fluid supply manifold for supplying fluid to the fluid passage portion, and the fluid passage portion, A separator that is located between the fluid supply manifold and introduces the fluid supplied from the fluid supply manifold into the fluid flow path portion, the fluid introduction portion including the fluid flow It is an object of the present invention to provide a fuel cell that has been subjected to a water repellent treatment that exhibits higher water repellency than a road portion.

  The present invention also relates to a fuel cell comprising a plurality of unit cells each including a membrane-electrode assembly and separators disposed on both sides of the membrane-electrode assembly, and a groove portion through which a fluid flows. A fluid flow path portion in which the inner wall surface of the groove portion is subjected to water repellent treatment, a fluid discharge manifold into which the fluid discharged from the fluid flow path portion is introduced, and the fluid flow path portion, A separator that is located between the fluid discharge manifold and discharges the fluid discharged from the fluid flow path portion to the fluid discharge manifold, the fluid discharge portion including the fluid flow It is an object of the present invention to provide a fuel cell that has been subjected to a water repellent treatment that exhibits higher water repellency than a road portion.

  Since the fuel cell having these configurations has a higher water repellency in the fluid introduction part and / or the fluid discharge part than the water repellency in the inner wall surface of the fluid flow path part (groove part) of the separator, the fluid introduction part And / or it can suppress that water retains in a fluid discharge part. Therefore, even when the fuel cell is started in a low temperature environment, it is possible to suppress the ice from adhering to the fluid introduction part and / or the fluid discharge part as well as the fluid flow path part. For this reason, it becomes possible to prevent the fluid introduction part and / or the fluid discharge part from being narrowed or blocked by the adhesion of ice, so that the fluid can be reliably introduced in an appropriate amount. Further, since the heat capacity necessary for raising the temperature in the cell can be reduced, the temperature in the cell can be rapidly raised (warmed up).

  In addition to the fluid discharge manifold and the fluid discharge portion that discharges the fluid discharged from the fluid flow passage portion to the fluid discharge manifold, the present invention is for supplying fluid to the fluid flow passage portion. A fluid introduction section that is located between the fluid flow path section and the fluid supply manifold and introduces the fluid supplied from the fluid supply manifold to the fluid flow path section. Both the fluid introduction part and the fluid introduction part may be subjected to a water repellent treatment that exhibits higher water repellency than the fluid flow path part.

  Further, the region of the separator that contacts the membrane-electrode assembly can be a non-water repellent treatment region (that is, a region that has not been subjected to water repellent treatment). With this configuration, a water-repellent film that does not have electrical conductivity is not formed in a region related to direct power generation of the separator, so that power generation of the fuel cell can be performed efficiently.

  In the fuel cell according to the present invention, the contact angle of the fluid introduction part and / or the fluid discharge part can be set to 150 degrees or more. With this configuration, the water repellency of the fluid introduction part and / or the fluid discharge part can be further improved, and water can be more reliably suppressed from remaining in the fluid introduction part and / or the fluid discharge part. can do. If the contact angle on the surface of the fluid introduction part and / or the fluid discharge part is high, the water or ice adhering to the surface is in point contact with the surface. It can be easily removed (peeled) from the surface.

  Furthermore, in the fuel cell according to the present invention, the contact angle of the inner wall surface of the groove can be set to 70 degrees or more and 110 degrees or less. By doing in this way, while being able to suppress more efficiently that water retains in a fluid introduction part and a fluid discharge part, the difference with the water repellency of the fluid introduction part and / or fluid discharge part, It is possible to further reliably prevent water from staying in the fluid introduction part and / or the fluid discharge part.

  Although the contact angle of the fluid introduction part and / or the fluid discharge part and the contact angle of the inner wall surface of the groove part are not necessarily limited, the contact angle of the fluid introduction part and / or the fluid discharge part may be It is necessary to be larger than the contact angle of the inner wall surface of the groove. By imparting water repellency to the groove, water and ice can be prevented from staying in the groove, and the water repellency of the fluid introduction part and / or the fluid discharge part can be made higher than the water repellency of the groove part. In order to set a larger value, it is preferable that the contact angle is in the range.

  The “fluid” referred to in the present invention may be either fuel gas or oxidizing gas. As a matter of course, the fluid may contain a component contained in the fuel gas or the oxidizing gas in a normal fuel cell, or may contain a component contained in the fuel off-gas or the oxidizing off-gas.

  The present invention also provides a fuel cell comprising: the fuel cell according to the present invention described above; a fluid supply unit that supplies fluid to the fuel cell; and a fluid discharge unit that discharges fluid discharged from the fuel cell. A system is provided.

  In the fuel cell system having this configuration, the water repellency of the fluid introduction part and / or the fluid discharge part is higher than the water repellency of the inner wall surface of the fluid flow path part (groove part) of the separator disposed in the fuel cell. Therefore, it is possible to prevent water from staying in the fluid introduction part and / or the fluid discharge part. Therefore, even when the fuel cell is started in a low temperature environment, it is possible to suppress the ice from adhering to the fluid introduction part and / or the fluid discharge part as well as the fluid flow path part. For this reason, it becomes possible to prevent the fluid introduction part and / or the fluid discharge part from being narrowed or blocked by the adhesion of ice, so that the fluid can be reliably introduced in an appropriate amount. Further, since the heat capacity necessary for raising the temperature in the cell can be reduced, the temperature in the cell can be rapidly raised (warmed up).

  The fuel cell system according to the present invention further includes a fluid supply amount control unit that controls a supply amount of the fluid supplied from the fluid supply unit, and the fluid supply amount control unit is configured to generate power when the fuel cell generates power. The amount of fluid supplied to the fuel cell can be reduced, and the amount of fluid supplied to the fuel cell can be increased when the fuel cell is not generating electricity. By configuring in this way, even if ice adheres to the groove portion of the separator and the fluid introduction portion and / or the fluid discharge portion, the ice is removed (peeled) by the fluid flowing during non-power generation. It can be discharged to the outside. At this time, since the water repellent treatment is applied to the groove portion of the separator and the fluid introduction portion and / or the fluid discharge portion, even if ice is attached, it can be easily removed by the fluid. In addition, since the water repellency of the fluid introduction part and / or the fluid discharge part is higher than the water repellency of the groove part, the ice adhering to the fluid introduction part and / or the fluid discharge part can be more easily removed by the fluid. Can do. Further, at the time of power generation, an appropriate amount of fluid necessary for power generation by the fuel cell can be supplied. Thus, by removing the adhering ice with the fluid, there is almost no need to raise the temperature inside the fuel cell above the freezing point, so that warm-up can be performed rapidly.

  The fluid supply amount control unit can alternately increase and decrease the amount of fluid supplied to the fuel cell at predetermined intervals. Alternatively, the fluid supply amount control unit can switch increase / decrease of the fluid amount in accordance with the allowable water content in the fuel cell. In this way, by repeating power generation and non-power generation (ice discharge), in addition to the above-described advantages, it is possible to simultaneously realize the temperature rise performance and the ice discharge performance.

  ADVANTAGE OF THE INVENTION According to this invention, while adhering to the separator and the ice adhering to a separator by freezing can be discharged | emitted outside efficiently, the fuel cell and fuel cell system which improved electric power generation efficiency can be provided. .

It is a block diagram which shows the fuel cell system which concerns on the Example of this invention. It is a top view of the separator which is a component of the fuel cell shown in FIG. FIG. 3 is an enlarged sectional view showing a part of the fuel cell shown in FIG. 2. It is a flowchart which shows the control method of switching of electric power generation and discharge | emission (non-electric power generation) in the fuel cell system based on the Example of this invention. It is a figure which shows the relationship between the electric power generation and waste_water | drain in the fuel cell system which concerns on the Example of this invention, an air flow rate, the emitted-heat amount, and the amount of water in a cell.

  Next, embodiments for carrying out the present invention will be described with reference to the drawings. In addition, the Example described below is the illustration for demonstrating this invention, and this invention is not limited only to these Examples. Therefore, the present invention can be implemented in various forms without departing from the gist thereof.

  1 is a block diagram showing a fuel cell system according to an embodiment of the present invention, FIG. 2 is a plan view of a separator that is a component of the fuel cell shown in FIG. 1, and FIG. 3 is a diagram of the fuel cell shown in FIG. FIG. 4 is a partially enlarged cross-sectional view, FIG. 4 is a flowchart showing a control method for switching between power generation and discharge (non-power generation) in a fuel cell system according to an embodiment of the present invention, and FIG. 5 is an embodiment of the present invention. It is a figure which shows the relationship between the electric power generation and waste_water | drain in the fuel cell system which concerns on, an air flow rate, the emitted-heat amount, and the amount of water in a cell. In the drawings, for easy understanding, the thickness, size, enlargement / reduction ratio, etc. of each member are not matched with the actual ones.

  In this embodiment, the case where this fuel cell system is applied to an in-vehicle power generation system of a fuel cell vehicle will be described. However, the present invention is not limited to such an application example, and any movement such as a ship, an aircraft, a train, etc. In addition to being applicable to a body and a walking robot, for example, it is also possible to apply to a stationary power generation system in which a fuel cell is used as a power generation facility for a building (house, building, etc.).

  As shown in FIG. 1, in the fuel cell system according to the embodiment of the present invention, an oxidizing gas (fluid containing air as a main component: hereinafter simply referred to as “air”) is supplied to the fuel cell 20 via an air supply path 71. To the air supply port. The air supply path 71 is provided with an air filter A1 that removes particulates from the air, a compressor A3 that pressurizes the air, a pressure sensor P4 that detects the supply air pressure, and a humidifier A21 that adds required moisture to the air. The air off gas discharged from the fuel cell 20 is discharged to the outside through the exhaust path 72. The exhaust path 72 is provided with a pressure sensor P1 that detects the exhaust pressure, a pressure adjustment valve A4, and a heat exchanger for the humidifier A21.

  On the other hand, fuel gas (fluid containing hydrogen as a main component: hereinafter simply referred to as “hydrogen gas”) is supplied from the hydrogen supply source 30 to the hydrogen supply port of the fuel cell 20 through the fuel supply path 74. The fuel supply path 74 includes a shutoff valve H100 that supplies or stops supplying hydrogen from the hydrogen supply source 30, a pressure sensor P6 that detects the supply pressure of hydrogen gas from the hydrogen supply source 30, and hydrogen gas to the fuel cell 20. The pressure regulating valve H9 for reducing and adjusting the supply pressure of the fuel, the pressure sensor P9 for detecting the hydrogen gas pressure downstream of the hydrogen pressure regulating valve H9, and the shutoff valve H21 for opening and closing between the hydrogen supply port of the fuel cell 20 and the fuel supply path 74. , And a pressure sensor P5 for detecting the inlet pressure of the hydrogen gas fuel cell 20 is provided.

  The hydrogen gas that has not been consumed in the fuel cell 20 is discharged to the hydrogen circulation path 75 as a hydrogen off-gas and returned to the downstream side of the hydrogen pressure regulating valve H9 in the fuel supply path 74. The hydrogen circulation path 75 includes a temperature sensor T31 that detects the temperature of the hydrogen off-gas, a shutoff valve H22 that communicates / blocks the fuel cell 20 and the hydrogen circulation path 75, a gas-liquid separator H42 that collects moisture from the hydrogen off-gas, and a hydrogen A drain valve H41 that collects the generated water in a tank (not shown) outside the hydrogen circulation path 75, a hydrogen pump H50 that pressurizes the hydrogen off-gas, and a backflow prevention valve H52 are provided. Further, the hydrogen circulation path 75 is connected to the exhaust path 72 by the purge flow path 76 via the discharge control valve H51.

  Further, a cooling passage 73 for circulating the cooling water is provided at the cooling water inlet / outlet of the fuel cell 20. The cooling path 73 includes a temperature sensor T1 that detects the temperature of the cooling water drained from the fuel cell 20, a radiator C2 that dissipates the heat of the cooling water to the outside, a pump C1 that pressurizes and circulates the cooling water, and a fuel cell. A temperature sensor T <b> 2 for detecting the temperature of the cooling water supplied to 20 is provided. The radiator C2 is provided with a cooling fan C13 that is rotationally driven by a motor.

  A part of the DC power generated by the fuel cell 20 is stepped down by the DC / DC converter 53 and charged to the secondary battery (power supply destination) 54. The traction inverter 51 and the auxiliary inverter 52 convert the DC power supplied from either or both of the fuel cell 20 and the secondary battery 54 into AC power and supply AC power to each of the traction motor M3 and the auxiliary motor M4. Supply.

  The control unit 50 is configured by a control computer system (not shown), and includes a required load such as an accelerator signal of a vehicle (not shown) and sensors (pressure sensor, temperature sensor, flow sensor, output ammeter, output voltmeter, etc.) of each part of the fuel cell system. ) To control the operation of valves and motors in each part of the system. Further, as will be described in detail later, the control unit 50 controls switching between power generation and discharge (non-power generation) in the fuel cell 20 according to the flowchart shown in FIG. That is, the control unit 50 also serves as a fluid supply amount control unit in the present invention.

  As shown in FIG. 3, the fuel cell 20 has a single cell 250 having a membrane-electrode assembly (hereinafter referred to as “MEA”) 220 and separators 230 and 240 disposed on both sides of the MEA 220. is doing. Then, a stack is formed by arranging terminals, insulators, and end plates (not shown) at both ends of the module group in which a plurality of single cells 250 are stacked in the cell stacking direction, and the stack is fastened and fixed in the cell stacking direction. ing.

  The MEA 220 includes an electrolyte membrane 211 made of an ion exchange membrane, and a fuel electrode 215 (anode) made up of a catalyst layer 212, a microporous layer 213, and a diffusion layer 214 is disposed on one surface of the electrolyte membrane 211, On the other surface of the electrolyte membrane 211, an oxidant electrode 219 (cathode) composed of a catalyst layer 216, a microporous layer 217, and a diffusion layer 218 is provided.

  As shown in FIGS. 2 and 3, the separator 240 disposed on the oxidant electrode 219 (cathode) side is a fluid flow path through which air flows in a region facing the MEA 220 and facing the power generation unit. A groove portion 241 is formed as a portion.

  At one end edge of the separator 240, an air supply manifold 242 for supplying air in the stacking direction of the single cells, a cooling medium inlet manifold 243 for supplying a cooling medium, and hydrogen gas are discharged. For this purpose, a hydrogen gas outlet manifold 244 is provided. Further, the other end edge of the separator 240 communicates in the stacking direction of the single cells, a hydrogen gas inlet manifold 245 for supplying hydrogen gas, a cooling medium outlet manifold 246 for discharging the cooling medium, And an air outlet manifold 247 for exhausting air.

  In addition, an air introduction portion 248 that introduces air supplied from the air supply manifold 242 into the groove portion 241 is provided between the air supply manifold 242 and the groove portion 241. On the other hand, an air discharge part 249 for discharging the air discharged from the groove part 241 to the air outlet manifold 247 is provided between the groove part 241 and the air outlet manifold 247.

  A water repellent layer 270 is formed on the inner wall surface of the groove 241 (portion not in contact with the diffusion layer 218) by performing a water repellent treatment. Examples of the water repellent treatment include a method of forming a film made of a fluorine resin such as Teflon (registered trademark) or PTFE, a silicone resin, or the like on the inner wall surface of the groove 241. In addition, it is preferable that the contact angle of the inner wall surface of the groove part 241 becomes 70 degrees or more and 110 degrees or less by this water repellent treatment.

  Further, a water repellent layer (not shown) is formed on the surfaces of the air introduction part 248 and the air discharge part 249 by performing a water repellent treatment that provides a higher water repellency than the inner wall surface of the groove part 241. ing. As the water repellent treatment, for example, HIREC (registered trademark: manufactured by NTT Advanced Technology Co., Ltd.) or Adesso WR (registered trademark: manufactured by Nikka Chemical Co., Ltd.) is applied to the surfaces of the air introduction unit 248 and the air discharge unit 249. To form a coating film, to form a composite plating film of a plated metal film and PTFE particles, to form a substantially conical microstructure film, and the like. In addition, it is preferable that the contact angle of the surface of the air introduction part 248 and the air discharge part 249 becomes 150 degree | times or more by this water repellent process.

  In addition, the region in contact with the diffusion layer 218 of the separator 240 is not subjected to water repellent treatment, so that the electrical conductivity of the region in contact with the diffusion layer 218 of the separator 240 is not impaired. Therefore, power generation can be performed efficiently. Note that a hydrophilic treatment may be performed on the region of the separator 240 that contacts the diffusion layer 218 as desired.

  The separator 230 in which the fuel electrode 215 (anode) is disposed has a configuration similar to that of the separator 240, and hydrogen gas circulates in a region facing the MEA 220 and facing the power generation unit. A groove portion is formed as a fluid flow path portion, a hydrogen gas introduction portion is provided between the groove portion and the hydrogen gas supply manifold, and a hydrogen gas discharge portion is provided between the groove portion and the hydrogen gas outlet manifold 244. In addition, the water repellency of the groove, the water repellency of the hydrogen gas introduction part and the hydrogen gas discharge part, and the effects obtained by this water repellency are the same as those of the separator 240, and thus detailed description thereof is omitted.

  Next, a method for controlling switching between power generation and discharge (non-power generation) in the fuel cell system according to the present embodiment will be described with reference to FIGS. 4 and 5.

  When the fuel cell system is activated, as shown in FIG. 4, the control unit 50 detects the stack temperature of the fuel cell 20 with the temperature sensor T1 (step S1), and the detected stack temperature is a predetermined freezing temperature ( For example, when the temperature exceeds 0 ° C. (step S2: YES), the process proceeds to step S3, and normal power generation (from the fuel cell 20 to the secondary battery 54, the auxiliary machine inverter 52, and the auxiliary machine motor M4) is performed. Power supply to the other). Thereafter, this flow is terminated.

  On the other hand, when the detected stack temperature is lower than a predetermined freezing temperature (for example, 0 ° C.), the process proceeds to step S4, the water content (A) in the cell is calculated, and the process proceeds to step S5. Here, the amount of generated water is an integral value of the generated current of the fuel cell 20, and the generated water is discharged as saturated water vapor, so the amount of discharged water is determined by the relationship between the gas flow rate and the temperature. Therefore, the water content (A) in the cell is calculated by (power generation current of the fuel cell 20) − (air flow rate, air temperature).

  Next, when the water content (A) in the cell is equal to or greater than the amount of water that is concerned that the air introduction part 248 and the air discharge part 249 are blocked (step S5: YES), step In S6, the control unit 50 stops power generation and controls the compressor A3 to increase the flow rate of air supplied to the fuel cell 20. By this operation, the ice adhering to the groove part 241, the air introduction part 248 and the air discharge part 249 of the separator 240 is removed, and the ice is efficiently discharged outside the system (outside the system). Thus, by removing the adhering ice with air, there is almost no need to raise the temperature above the freezing point in the stack, so that warm-up can be performed rapidly. Next, in step S7, the water content (A) in the cell is calculated again, and the process proceeds to step S8.

  In step S8, when the water content (A) in the cell is equal to or less than the amount of water (blocking avoidance water amount) that does not cause the air introduction unit 248 and the air discharge unit 249 to be blocked (step S8: YES), this flow is performed. Exit. On the other hand, when the water content (A) in the cell exceeds the amount of water (blocking avoidance water amount) at which the air introduction unit 248 and the air discharge unit 249 are not likely to be blocked, the process returns to step S6.

  On the other hand, when the water content (A) in the cell is less than the amount of water that is concerned that the air introduction part 248 and the air discharge part 249 are blocked (step S5: NO), step S9 The control unit 50 starts power generation and controls the compressor A3 to reduce the flow rate of the air supplied to the fuel cell 20 and stop the removal of the ice. Thereafter, this flow is terminated.

  Here, the relationship among the air flow rate by switching between power generation and discharge (non-power generation), the calorific value, and the moisture content in the cell changes as shown in FIG. That is, during power generation, the air flow rate decreases and the heat generation amount increases. Further, the water content in the cell gradually increases from the start of power generation. On the other hand, at the time of discharge (non-power generation), the air flow rate increases and the heat generation amount decreases. Further, the water content in the cell gradually decreases from the start of discharge.

  For example, if the amount of generated water required to raise the temperature of a single cell from −30 ° C. to 0 ° C. is 3 g / cell, in the case of a fuel cell in which 300 single cells are stacked, the amount of heat required is 357 kJ. Assuming that the calorific value of the fuel cell whose temperature is being raised is 30 kW, 357/30 = 12 seconds. In the fuel cell system according to the present embodiment, it is not necessary to thaw the ice due to heat generation, so that the temperature inside the cell can be raised about 12 seconds faster than before.

  In this embodiment, the case where the flow rate of air supplied to the fuel cell 20 is increased or decreased has been described. However, the present invention is not limited to this, and the flow rate of hydrogen gas may be increased or decreased. Further, the air flow rate and the hydrogen gas flow rate may be increased or decreased.

  In this embodiment, the air introduction part 248 that introduces the air supplied from the air supply manifold 242 into the groove part 241 and the air discharge part 249 that exhausts the air discharged from the groove part 241 to the air outlet manifold 247. However, the present invention is not limited to this, and the water repellent treatment is applied to either the air introduction part 248 or the air discharge part 249 as desired. It may be. The same applies to the hydrogen gas introduction part and the hydrogen gas discharge part.

  DESCRIPTION OF SYMBOLS 20 ... Fuel cell, 50 ... Control part, 220 ... MEA, 230, 240 ... Separator, 241 ... Groove part, 248 ... Air introduction part, 249 ... Air discharge part, 250 ... Single cell, 270 ... Water-repellent layer

Claims (10)

A fuel cell comprising a plurality of unit cells each including a membrane-electrode assembly and separators disposed on both sides of the membrane-electrode assembly,
A fluid passage portion having a groove portion through which a fluid flows, and a water repellent treatment applied to an inner wall surface of the groove portion, a fluid supply manifold for supplying fluid to the fluid passage portion, and the fluid passage portion A separator having a fluid introduction part that is located between the fluid supply manifold and introduces the fluid supplied from the fluid supply manifold to the fluid flow path part,
The fuel introduction part is a fuel cell that is subjected to a water repellency treatment that exhibits higher water repellency than the fluid flow path part. A fuel cell comprising a plurality of unit cells each including a membrane-electrode assembly and separators disposed on both sides of the membrane-electrode assembly,
A fluid passage portion having a groove portion through which a fluid flows, a water repellent treatment applied to an inner wall surface of the groove portion, a fluid discharge manifold into which the fluid discharged from the fluid passage portion is introduced, and A separator having a fluid discharge portion located between the fluid flow passage portion and the fluid discharge manifold and discharging the fluid discharged from the fluid flow passage portion to the fluid discharge manifold;
The fluid discharge part is a fuel cell that is subjected to a water repellent treatment that exhibits higher water repellency than the fluid flow path part. The separator is located between a fluid supply manifold that supplies fluid to the fluid flow path section, and between the fluid flow path section and the fluid supply manifold, and the fluid supplied from the fluid supply manifold is the fluid A fluid introduction part to be introduced into the flow path part,
The fuel cell according to claim 2, wherein the fluid introduction part is subjected to water repellency treatment that exhibits higher water repellency than the fluid flow path part.   4. The fuel cell according to claim 1, wherein a region of the separator that is in contact with the membrane-electrode assembly is a non-water-repellent treatment region. 5.   The fuel cell according to any one of claims 1 to 4, wherein a contact angle of at least one of the fluid introduction part and the fluid discharge part is 150 degrees or more.   The fuel cell according to any one of claims 1 to 5, wherein a contact angle of an inner wall surface of the groove is 70 degrees or more and 110 degrees or less. A fuel cell according to any one of claims 1 to 6,
A fluid supply unit for supplying fluid to the fuel cell;
A fluid discharge unit for discharging the fluid discharged from the fuel cell;
A fuel cell system comprising: A fluid supply amount control unit for controlling a supply amount of fluid supplied from the fluid supply unit;
The fluid supply amount control unit decreases the amount of fluid supplied to the fuel cell during power generation of the fuel cell, and increases the amount of fluid supplied to the fuel cell during non-power generation of the fuel cell. Fuel cell system.   The fuel cell system according to claim 8, wherein the fluid supply amount control unit alternately repeats increase / decrease in the amount of fluid supplied to the fuel cell at predetermined intervals.   The fuel cell system according to claim 8, wherein the fluid supply amount control unit switches increase / decrease of the fluid amount in accordance with an allowable water content in the fuel cell.

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