JP2012151062A - Fuel cell device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell device which prevents humidification performance of a membrane-type humidifier from being damaged and furthermore prevents a layout from being largely restricted.SOLUTION: The fuel cell device includes: a fuel cell 10; a humidifier 32 which obtains moisture from cathode off-gas exhausted from the fuel cell 10 and gives the obtained moisture to supply gas supplied to the fuel cell 10; a cooler 33 which is disposed between the fuel cell 10 and the humidifier 32, has a steam permeable membrane in the inside thereof, and lowers the temperature of the cathode off-gas by bringing the cathode off-gas into contact with one of one surface and the other surface of the steam permeable membrane and liquid water into contact with the other, and then by taking heat from the cathode off-gas; a recovery unit 35 which is disposed on an off-gas flow passage through which the cathode off-gas flows; and a recovered water introduction piping b9 which supplies the recovered water recovered by the recovery unit 35 to the cooler 33 as the liquid water.

Description

  The present invention relates to a fuel cell device provided with a membrane humidifier.

  In solid polymer membrane type fuel cells, if the membrane (electrolyte membrane) of the fuel cell is too dry, the power generation performance will deteriorate. Therefore, a membrane-type humidifier that provides moisture to the supply gas will be provided to moderately humidify the membrane. Various provisions have been proposed. This type of humidifier uses, for example, off gas discharged from the fuel cell to exchange moisture between the supply gas supplied to the fuel cell and the off gas. However, when the operating temperature of the fuel cell becomes high, the relative humidity of the off gas discharged from the fuel cell is less than 100%, so that the humidifying performance of the humidifier may not be fully exhibited. Thus, a technology has been proposed in which a cooler having an air-cooled or water-cooled heat exchanger is provided on an off-gas flow path between a fuel cell and a humidifier, and the humidity is increased by lowering the temperature of the off-gas (for example, Patent Document 1).

Japanese Patent Laying-Open No. 2009-152013 (FIG. 1)

  However, when the air-cooled cooler described in Patent Document 1 is mounted on a vehicle, it needs to be installed in a bumper opening or the like, and there is a problem that the layout is restricted. Even when a water-cooled cooler is mounted, there is a problem that the layout is restricted by the addition of a radiator.

  An object of the present invention is to solve the above-described conventional problems, and to provide a fuel cell device that does not impair the humidification performance of the membrane humidifier and that does not greatly restrict the layout.

  The present invention relates to a fuel cell, a membrane humidifier that obtains moisture from off-gas discharged from the fuel cell and supplies moisture to a supply gas supplied to the fuel cell, the fuel cell, and the membrane humidifier. Between which the off-gas is brought into contact with one of the one surface and the other surface of the water-vapor permeable membrane, and liquid water is brought into contact with the other, thereby removing heat from the off-gas. And a cooler for lowering the temperature of the off gas.

  According to this, it is possible to reduce the temperature of the offgas by utilizing the latent heat (vaporization heat) when the liquid water evaporates by bringing the water vapor into contact with one surface of the water vapor permeable membrane. . As a result, the temperature of the off gas supplied to the membrane humidifier can be optimized.

  That is, when the operating temperature of the fuel cell becomes high, the relative humidity of the off gas falls below 100%, and the membrane humidifier dries up (the humidification efficiency is excessively lowered in the membrane humidifier). There is a possibility that the humidification performance cannot be exhibited. Therefore, by disposing a cooler using a water vapor permeable membrane between the fuel cell and the membrane humidifier, the relative humidity of the off gas can be increased by cooling the off gas. In this way, the relative humidity of the off gas can be prevented from falling below 100%, and the membrane humidifier can be prevented from drying up.

  In addition, by including a water vapor permeable membrane as a cooler, it is possible to reduce the size of the cooler itself compared to a cooler equipped with a water-cooled or air-cooled heat exchanger, and the layout Can be prevented from being greatly restricted. In addition, when the cooler is mounted on a vehicle, it is not necessary to arrange it in a bumper opening or the like or to add a large heat exchanger such as a radiator, so that it is possible to prevent the layout from being greatly restricted. In addition, when the off-gas humidity is 100% or more, the moisture that has permeated through the water vapor permeable membrane does not evaporate, so the cooling function does not work, and there is no possibility of reducing the humidification performance due to extra cooling. On the other hand, when it is set as the cooler provided with heat exchangers, such as an air cooling type, although the structure which bypasses a heat exchanger is needed, the addition of such a structure part can be avoided.

  A condensed water recovery unit disposed on an off-gas channel through which the off-gas flows; a recovered water supply channel for supplying the recovered water recovered by the condensed water recovery unit to the cooler as the liquid water; It is characterized by providing.

  According to this, the liquid water discharged from the fuel cell (condensed water, generated water) is stored in the condensed water recovery device, so that the liquid water discharged from the fuel cell is effectively used to cool off-gas. Can do. Further, it is not necessary to separately provide a device for supplying liquid water to the cooler.

  The cooler includes a plurality of hollow fiber-shaped water vapor permeable membranes extending vertically in the vertical direction.

  According to this, even if the liquid water (water level) in the cooler fluctuates up and down, the liquid water can be brought into uniform contact with the respective water vapor permeable membranes, so that the off-gas introduced into the cooler The heat of the heat is evenly deprived and the cooling effect can be enhanced.

  Further, the temperature sensor for determining the temperature of the off gas introduced into the membrane humidifier, and the relationship between the preset generated power and the allowable temperature value of the off gas introduced into the membrane humidifier, A control unit that obtains the allowable temperature value from the generated electric power and adjusts the generated electric power by comparing the allowable temperature value and a temperature value of the temperature sensor.

  According to this, when the generated power is high and the temperature value (actual temperature) of the temperature sensor is higher than the allowable temperature value, the generated power is controlled to decrease. By reducing the generated power in this way, the allowable temperature value increases, so that the limit (suppression control) of the generated power is relaxed. On the other hand, when the generated power is low and the temperature value (actual temperature) of the temperature sensor is higher than the allowable temperature value, the generated power is controlled to increase. Since the allowable temperature value is increased by increasing the generated power in this way, the limit (increased control) of the generated power is relaxed.

  In addition, the cooler includes a water level sensor that detects a water level of the recovered water and a discharge valve that discharges the recovered water.

  According to this, the capability as a cooler can be appropriately maintained by managing the water level of the liquid water in the cooler.

  Moreover, the control part which restrict | limits the said generated electric power based on the water level of the said water level sensor using the relationship between the preset water level of the said cooler and generated electric power is provided.

  According to this, when the water level of the cooler is low, the generated power is limited (suppressed), the fuel cell is easily oversaturated, and liquid water (condensed water) is secured as much as possible. It can prevent water shortage.

  Further, when stopping the operation of the fuel cell device, at least one output value of a second temperature sensor that detects the temperature of the cooler and a timer that measures an elapsed time from the stop of the operation of the fuel cell device is used. And a control unit that opens the discharge valve when the output value satisfies a predetermined condition.

  According to this, it is possible to prevent the startability from being deteriorated due to the breakage of the water vapor permeable membrane due to freezing or the supply of the low-temperature off-gas to the membrane humidifier when the fuel cell device is started. The predetermined condition is when the temperature detected by the second temperature sensor is lower than the predetermined temperature, or when the elapsed time from the stop of the operation of the fuel cell device measured by the timer has passed a predetermined time. is there.

  According to the present invention, it is possible to provide a fuel cell device without impairing the humidification performance of the membrane humidifier and without greatly restricting the layout.

It is a whole lineblock diagram showing the fuel cell device concerning this embodiment. (A) is schematic which shows the structure of a cooler, (b) is sectional drawing explaining the flow path of the offgas and liquid water of a cooler. It is a flowchart which shows control of generated electric power. It is a map which shows the relationship between the allowable temperature of the offgas of a cooler exit, and generated electric power. It is a flowchart which shows another control of generated electric power. It is a map which shows the relationship between the water level of a cooler, and the restriction | limiting ratio of generated electric power. It is a flowchart which shows control of the discharge valve at the time of an operation stop. It is a flowchart which shows another control of the discharge valve at the time of an operation stop. It is a whole block diagram which shows the modification of the fuel cell apparatus which concerns on this embodiment. It is a whole block diagram which shows the other modification of the fuel cell apparatus which concerns on this embodiment. It is a whole block diagram which shows the other modification of the fuel cell apparatus which concerns on this embodiment.

  Hereinafter, a fuel cell device according to an embodiment of the present invention will be described with reference to the drawings. The fuel cell devices 1A to 1D of the present embodiment require electricity such as fuel cell vehicles such as four-wheels and two-wheels, mobile devices such as ships and airplanes, or stationary devices for home use and business use. Applicable to everything. Hereinafter, a fuel cell vehicle will be described as an example.

  As shown in FIG. 1, the fuel cell device 1A according to the present embodiment includes a fuel cell 10, an anode system 20, a cathode system 30, a cooling system 40, and a control system 50.

The fuel cell 10 is, for example, a polymer electrolyte fuel cell (Polymer Electrolyte Fuel Cell).
PEFC), stacking multiple unit cells in the thickness direction with MEA (Membrane Electrode Assembly) sandwiched between a pair of separators (not shown), and connecting each unit cell electrically in series The fuel cell stack.

  The MEA is configured by sandwiching a solid polymer electrolyte membrane (hereinafter abbreviated as an electrolyte membrane) made of a cation exchange membrane between an anode and a cathode. The anode and the cathode are composed of, for example, a gas diffusion layer made of carbon paper or the like, and an electrode catalyst layer formed by applying porous carbon particles having a platinum alloy supported on the surface to the surface of the gas diffusion layer. The

  The separator is made of a conductive metal material such as carbon, and has an anode channel 11 through which hydrogen (fuel gas) flows, a cathode channel 12 through which air (oxidant) flows, and a refrigerant that cools the fuel cell 10. Refrigerant flow paths 13 through which are circulated are respectively formed.

  In the fuel cell 10 configured as described above, hydrogen is supplied to the anode and oxygen in the air is supplied to the cathode, so that the fuel cell 10 can generate power by the action of the catalyst contained in the anode and the cathode. It becomes. Further, when the fuel cell 10 generates electric power, water is generated on the cathode side, and this generated water is discharged from the outlet of the cathode channel 12 as condensed water or water vapor, and passes through the electrolyte membrane and passes through the electrolyte channel. It is discharged from the exit.

  The fuel cell 10 is electrically connected to an external load, and the fuel cell 10 generates power when a current is taken out by the external load. The external load includes an air pump 31, a refrigerant pump 43, a high-voltage battery (not shown), a travel motor (not shown), and the like which will be described later.

  The anode system 20 supplies and discharges hydrogen to and from the anode of the fuel cell 10 and includes a gas-liquid separator 21, a drain valve 22, and a purge valve 23. The anode system 20 is configured such that hydrogen supplied from a high-pressure hydrogen tank (not shown) via a shutoff valve and a pressure reducing valve is supplied to the inlet of the anode flow path 11 via a pipe a1. The unreacted hydrogen discharged from the outlet of the anode channel 11 is circulated so as to return to the pipe a1 through the pipe a2, the gas-liquid separator 21, and the pipe a3. Although not shown, means for circulating hydrogen include an ejector and a rotary pump.

  The gas-liquid separator 21 has a function of separating moisture and unreacted hydrogen contained in the anode off-gas discharged from the outlet of the anode flow path 11, and stores a moisture (liquid water) (non-reacting water). (Shown).

  The gas-liquid separator 21 is configured so that, for example, when the anode off gas collides with the wall surface in the gas-liquid separator 21, the moisture contained therein is dropped in the space by the action of gravity and stored in the bottom. Yes. The moisture here is not only condensed water discharged from the outlet of the anode channel 11 but also water vapor discharged from the outlet of the anode channel 11 hits the wall surface in the gas-liquid separator 21 and the like. Is included.

  The drain valve 22 is, for example, a normally closed type, and is configured to be connected to the storage portion of the gas-liquid separator 21 via a pipe a4 and to be connected to a diluter 36, which will be described later, and a pipe a5. ing. Further, the drain valve 22 is opened by the control unit 51 described later, so that the liquid water (condensed water and condensed water) stored in the storage unit is discharged to the diluter 36 through the pipes a4 and a5. The The timing for opening the drain valve 22 may be determined by a water level sensor (not shown) that detects the water level in the gas-liquid separator 21, or may be opened periodically, or The amount of water generated by the amount of power generation may be integrated, and the valve may be opened when the integrated value reaches a predetermined value.

  The purge valve 23 is, for example, a normally closed type, and the impurities accumulated in the hydrogen circulation flow path (the anode flow path 11 and the flow paths of the pipes a1 to a3) during power generation by opening the valve are outside the vehicle (fuel cell). Discharged to the outside of the apparatus 1A). The purge valve 23 is connected to the pipe a3 through the pipe a6 and is connected to the pipe a5 through the pipe a7. Note that the purge valve 23 is controlled to be opened and closed by the control unit 51 according to a decrease in the hydrogen concentration in the hydrogen circulation passage (a decrease in power generation performance) and / or periodically.

  The cathode system 30 supplies and discharges air (oxygen) to and from the cathode of the fuel cell 10, and includes an air pump (oxidant pump) 31, a humidifier (membrane humidifier) 32, a cooler 33, and a back pressure valve 34. , A recovery unit (condensate recovery unit) 35 and a diluter 36 are included. The air pump 31 is connected to the inlet of the cathode channel 12 via the pipe b1, the humidifier 32, and the pipe b2. The outlet of the cathode channel 12 is connected to the outside of the vehicle via a pipe b3, a cooler 33, a pipe b4, a humidifier 32, a pipe b5, a back pressure valve 34, a pipe b6, a recovery unit 35, a pipe b7, a diluter 36, and a pipe b8. Communicate. In the present embodiment, the pipes b3 to b8 correspond to off gas passages.

  The air pump 31 is, for example, a mechanical supercharger (such as a supercharger) driven by a motor (not shown), and compresses air taken from the outside of the vehicle and supplies the compressed air to the cathode of the fuel cell 10.

  The humidifier 32 is of a membrane type that humidifies dry air (supply gas, oxidant gas) supplied from the air pump 31. For example, a hollow fiber membrane in which a plurality of hollow fiber membranes that are moisture exchange membranes are bundled It has a case (not shown) in which a bundle is accommodated, and is formed with an inlet 32a and an outlet 32b for dry air from the air pump 31, and an inlet 32c and an outlet 32d for cathode offgas (offgas), respectively.

  In such a humidifier 32, for example, the dry air from the air pump 31 passes through the inside of the hollow fiber membrane in the case, and the cathode off gas containing moist air passes through the outside of the hollow fiber membrane. The water vapor contained in the cathode off-gas enters into the formed pores, and the water vapor moves from the outside of the membrane to the inside through the pores of the hollow fiber membrane, so that the water vapor is passed to the dry air (supply gas) and dried. Air is humidified. The dry air may pass outside the hollow fiber membrane and the cathode offgas may pass inside the hollow fiber membrane. The humidifier 32 is not limited to a hollow fiber membrane, and may be formed of other types of moisture permeable membranes such as a flat membrane.

  The cooler 33 has a function of cooling the cathode offgas (offgas) discharged from the outlet of the cathode channel 12 of the fuel cell 10, and the offgas channel (pipe b3, pipe 3) between the fuel cell 10 and the humidifier 32. b4).

  The cooler 33 is formed with an inlet 33a through which the cathode offgas is introduced and an outlet 33b through which the cathode offgas is led out, and liquid water (recovered water, condensed water) is introduced as a coolant for cooling the cathode offgas. An inlet 33c to be discharged and an outlet 33d to which liquid water is led out are formed. The inlet 33c of the cooler 33 is connected to a recovery unit 35 which will be described later via a recovered water introduction pipe (recovered water supply flow path) b9, and the outlet 33d of the cooler 33 will be described later via a recovered water outlet pipe b10. A diluter 36 is connected. The cooler 33 is connected to a pipe 33e for discharging liquid water stored in the cooler 33, and a normally closed discharge valve 33f is provided on the pipe 33e. The specific configuration of the cooler 33 will be described later.

  The back pressure valve 34 is configured by a valve whose opening degree can be adjusted, such as a butterfly valve, and has a function of adjusting the pressure of the air (cathode pressure) supplied to the cathode of the fuel cell 10.

  The recovery device (condensate water recovery device) 35 is a recovery space (storage space) for recovering liquid water (condensate water) discharged from the outlet of the cathode channel 12 through the cooler 33, the humidifier 32 and the back pressure valve 34. have. The bottom of the recovery space is connected to the upstream end of the recovered water introduction pipe b9. The liquid water recovered by the recovery device 35 is not only the water discharged as condensed water from the outlet of the cathode flow channel 12 but also the water vapor radiates heat from the cathode flow channel 12 to the recovery device 35. As the cathode offgas temperature decreases, the water contained in the cathode offgas is condensed (condensed), and heat is dissipated by colliding with and contacting the wall surface in the collector 35, and the cathode offgas temperature is reduced. By being reduced, moisture formed by condensation (condensation) of water vapor contained in the cathode off-gas is also included.

  In addition, an orifice 35 a is provided in the recovered water introduction pipe b <b> 9 that connects the recoverer 35 and the cooler 33. The orifice 35a can make the flow rate of the liquid water supplied from the recovery device 35 to the cooler 33 constant, and the cathode off-gas via the water vapor permeable membrane 33j (see FIG. 2A) of the cooler 33. Is prevented from flowing back into the recovery device 35. The liquid water recovered (stored) by the recovery device 35 is pushed out toward the cooler 33 by being pushed out to the recovery water introduction pipe b <b> 9 by the pressure of the cathode off gas introduced into the recovery device 35. If the pressure when supplying liquid water from the collector 35 to the cooler 33 via the recovered water introduction pipe b9 is insufficient, a pump for pumping may be arranged on the recovered water introduction pipe b9. Good.

  The diluter 36 mixes the hydrogen contained in the anode off-gas discharged from the outlet of the anode flow path 11 and the cathode off-gas (mainly air) discharged from the outlet of the cathode flow path 12, and falls below a prescribed hydrogen concentration. It has a function of diluting. The diluted gas is discharged outside the vehicle through the pipe b8, a silencer (not shown), and the like.

  The cooling system 40 has a function of circulating the refrigerant in the fuel cell 10 to cool the fuel cell 10. The outlet of the refrigerant flow path 13 is connected to the inlet of the radiator 41 through the pipe c 1, and the outlet of the radiator 41 is It is connected to the inlet of the refrigerant flow path 13 via a pipe c2, a thermostat valve 42, a pipe c3, a refrigerant pump 43, and a pipe c4. The cooling system 40 has a bypass pipe c5 that bypasses the radiator 41, and one end on the upstream side of the bypass pipe c5 is connected to the pipe c1, and the other end on the downstream side is connected to the thermostat valve 42.

  In such a cooling system 40, when the fuel cell device 1A is started, the thermostat valve 42 is switched to the bypass pipe c5 side to promote warming up of the fuel cell 10, and when the operating temperature of the fuel cell 10 exceeds a predetermined temperature. In addition, the thermostat valve 42 is switched so that the flow path passing through the radiator 41 is enlarged.

  The control system 50 includes a control unit 51, an IG 52, a timer 53, a voltage controller 54, a cooler inlet temperature sensor S1, a cooler outlet temperature sensor S2, a refrigerant temperature sensor S3, a cooler temperature sensor S4, a water level sensor S5, and the like. It is configured.

  The control unit 51 includes a CPU (Central Processing Unit), a ROM (Read Only Memory) in which a program is recorded, a RAM (Random Access Memory), various interfaces, an electronic circuit, and the like, and includes an air pump 31 and a refrigerant pump 43. The rotation speed of each motor (not shown) is controlled, the start signal from the IG 52, the time (output value) measured by the timer 53, the cooler inlet temperature sensor S1, the cooler outlet temperature sensor S2, and the refrigerant temperature sensor S3. , The temperature (output value) from the cooler temperature sensor S4, and the water level from the water level sensor S5 are acquired, and the drain valve 22, purge valve 23, and discharge valve 33f are controlled to open and close.

  Further, the control unit 51 limits (suppresses or increases) the generated power of the fuel cell 10 according to the allowable temperature of the cathode offgas at the outlet 33b of the cooler 33 (allowable temperature of the cathode offgas introduced into the humidifier 32). . Moreover, the control part 51 controls generated electric power according to the water level by water level sensor S5, ie, raises the restriction | limiting ratio of generated electric power as water level becomes low, and makes generated electric power small.

  By the way, if water remains in the cooler 33, the water vapor permeable membrane 33j is damaged due to freezing, or the cathode cooled by the cooler 33 when the fuel cell device 1A is started next time (IG-ON). Off-gas (off-gas) is supplied to the humidifier 32. For this reason, the supply gas (dry air) supplied from the air pump 31 to the fuel cell 10 is cooled, and the warm-up of the fuel cell device 1A is impaired.

  Therefore, when the operation of the fuel cell device 1A is stopped (IG-OFF), the control unit 51 determines whether or not to open the discharge valve 33f according to the temperature in the cooler 33 detected by the cooler temperature sensor S4. The liquid water stored in the cooler 33 may be discharged as necessary.

  In addition, when the operation of the fuel cell device 1A is stopped (IG-OFF), the control unit 51 determines whether or not to discharge the liquid water stored in the cooler 33 after a predetermined time has elapsed since the operation stop. Also good. The predetermined time here can be changed based on the temperature value detected by the cooler temperature sensor S4, for example. That is, when the cooler temperature is low, the predetermined time (time until the discharge valve 33f is opened) is set short, and when the cooler temperature is high, the predetermined time (time until the discharge valve 33f is opened). ) Is set longer.

  The voltage controller 54 includes a buck-boost converter and the like, and generates power output from the fuel cell 10 based on a voltage (current) command value output from the control unit 51, that is, a power generation command for the fuel cell 10. It has a function to control. When the voltage controller 54 is controlled by the control unit 51, the generated power taken out from the fuel cell 10 can be raised or lowered. In the present embodiment, the voltage control unit 54 and the control unit 51 constitute the control unit described in the claims.

  As shown in FIG. 2, the cooler 33 includes, for example, a cylindrical case 33g, and a lower cover 33h having a space into which cathode offgas (offgas) is introduced is formed in the lower part of the case 33g in the vertical vertical direction. An upper cover 33i having a space from which the cathode off gas is led out is formed in the upper part in the vertical vertical direction. Further, in the case 33g, a plurality of hollow fiber-shaped water vapor permeable membranes 33j made of polyimide or the like are bundled and accommodated as a hollow fiber membrane bundle 33k. The hollow fiber membrane bundle 33k is arranged so as to extend in the vertical vertical direction, and the case 33g is inserted through potting members 33l and 33m (sealing portions) whose both ends in the vertical vertical direction are formed of epoxy resin or the like. It is fixed to the inner wall. As a result, the space between the outer peripheral surfaces of the respective water vapor permeable membranes 33j and the space between the outer peripheral surface of the water vapor permeable membrane 33j and the inner wall surface of the case 33g are blocked.

  By the way, when the hollow fiber membrane bundle 33k is arranged so as to extend in the horizontal direction in the cooler 33, when the liquid water level (water surface) in the cooler 33 fluctuates up and down, it is above the water surface. In the disposed water vapor permeable membrane 33j, there is no portion in contact with the liquid water, and the liquid water cannot be uniformly contacted with each water vapor permeable membrane 33j. However, in this embodiment, the hollow fiber membrane bundle 33k is arranged so as to extend in the vertical vertical direction, so that the liquid water recovered in the cooler 33 (recovered water) as indicated by dots in FIG. Even when the water level fluctuates up and down, liquid water can be evenly contacted with the respective water vapor permeable membranes 33j.

  In the cooler 33, the pipe b3 is connected to the lower cover 33h, and the pipe b4 is connected to the upper cover 33i. Thereby, the cathode off gas introduced into the lower cover 33 through the pipe b3 flows upward inside the water vapor permeable membrane 33j, and is discharged to the outside of the cooler 33 through the upper cover 33i and the pipe b4. The

  The cooler 33 is connected to the peripheral surface of the case 33g with a recovered water introduction pipe b9 into which liquid water (recovered water) is introduced and a recovered water outlet pipe b10 from which liquid water (recovered water) is derived. ing. The recovered water introduction pipe b9 and the recovered water outlet pipe b10 communicate with the recovery space P (see FIG. 2B) between the potting members 33l and 33m of the case 33g and are positioned above the recovery space P. So connected. Thereby, the liquid water introduced from the recovered water introduction pipe b9 is accumulated in the recovery space P, and is discharged to the diluter 36 through the recovered water outlet pipe b10 when the recovery space P becomes full. It is configured.

  In the cooler 33 configured as described above, the cathode off-gas contacts the inside (one surface) of the hollow fiber of the water vapor permeable membrane 33j, and the liquid water contacts the outside (other surface) of the hollow fiber of the water vapor permeable membrane 33j. Thus, the cathode offgas is cooled by taking the heat from the cathode offgas by the liquid water using the latent heat when the liquid water evaporates.

  Next, power generation control in the fuel cell apparatus 1A according to the present embodiment will be described with reference to FIGS. FIG. 3 is a flowchart showing the control of the generated power, and FIG. 4 is a map showing the relationship between the allowable off-gas temperature at the cooler outlet and the generated power.

  As shown in FIG. 3, when the fuel cell 10 is started, the control unit 51 determines the allowable cathode off-gas temperature at the outlet of the cooler 33, which is obtained from the generated power of the fuel cell 10 based on the map shown in FIG. It is determined whether or not the temperature is lower than the cathode off-gas temperature at the outlet 33b of the actual (current) cooler 33. The actual cathode off-gas temperature at the outlet 33b of the cooler 33 is detected by the cooler outlet temperature sensor S2.

  The map shown in FIG. 4 shows the relationship between the generated power and the allowable temperature at the outlet 33b of the cooler 33, and is determined in advance by experiments, simulations, and the like. That is, the region R1 lower than a certain generated power has a region where the allowable temperature decreases as the generated power decreases, and the region R2 prioritizes the state of the fuel cell 10, while the region R2 higher than the certain generated power. Then, it has an area | region where allowable temperature falls as generated electric power becomes high, and is an area | region which gives priority to the state of the humidifier 32. FIG. Note that the allowable temperature increases as the generated power increases in the region R1 because more liquid water is generated as the generated power of the fuel cell 10 increases, so that the liquid water in the fuel cell 10 is excessive. This is to prevent flooding from occurring. In addition, the allowable temperature decreases as the generated power increases in the region R2, because the temperature of the fuel cell becomes too high and the relative humidity of the cathode offgas falls below 100%, and the humidifier 32 is dried up. It is for preventing.

  In step S101, when the control unit 51 determines that the allowable temperature is not lower than the actual cathode offgas temperature of the outlet of the cooler 33 (No), the actual cathode offgas temperature is shown in the map of FIG. Since the allowable temperature is not exceeded, the process of step S101 is repeated. If the control unit 51 determines that the allowable temperature is lower than the actual cathode off gas temperature (Yes), the control unit 51 proceeds to step S102 and controls the voltage controller 54 according to the map of FIG. Control is performed so as to increase or decrease the generated electric power extracted from 10.

  For example, as indicated by reference numeral Q1 in the region R2 in FIG. 4, when the generated power is high and the actual cathode offgas temperature Ts in the generated power W1 exceeds the allowable temperature Ta based on this map, the generated power Is reduced from W1 to W2. By reducing the generated power in this way, the temperature of the fuel cell 10 is lowered and the temperature of the cathode offgas is lowered, so that the humidity of the cathode offgas discharged from the fuel cell 10 is increased, and the cathode offgas having a relative humidity of 100% is produced. Will be generated. Since the allowable temperature Ta increases due to the limitation (decrease) of the generated power, the actual cathode offgas temperature Ts falls within the allowable temperature range (No in S101), and the limitation (suppression control) of the generated power is eliminated.

  In addition, as indicated by reference numeral Q2 in the region R1 of FIG. 4, when the generated power is low and the actual cathode offgas temperature Ts in the generated power W3 exceeds the allowable temperature Tb based on the map, the generated power is reduced. Raise from W3 to W4. By increasing the generated power in this way, the temperature of the fuel cell 10 is increased, the humidity of the cathode offgas that was flooded due to oversaturation is reduced, and the outlet gas (cathode offgas) of the stable cooler 33 with a relative humidity of 100% is reduced. ) Is generated. Since the allowable temperature Tb increases as the generated power increases, the actual cathode offgas temperature Ts falls within the allowable temperature range (No in S101), and the generated power limit (rising control) is removed.

  In step S101 described above, the case of the cooler outlet temperature sensor S2 has been described as an example of the temperature sensor. However, the present invention is not limited to this, and the cooler inlet temperature sensor S1 and the refrigerant temperature sensor S3 are not limited thereto. You may judge using. Alternatively, although not shown, the determination may be made based on the temperature at which the anode offgas (offgas) of the pipe a2 at the outlet of the anode channel 11 and the temperature of the fuel cell 10 are directly detected. In addition, about the temperature by cooler inlet temperature sensor S1, refrigerant | coolant temperature sensor S3, etc., the detected temperature may be correct | amended and you may make it compare the corrected temperature value and allowable temperature value.

  Further, another power generation control in the fuel cell device 1A according to the present embodiment will be described with reference to FIGS. FIG. 5 is a flowchart showing another control of generated power, and FIG. 6 is a map showing the relationship between the water level of the cooler and the limit ratio of generated power.

  As shown in FIG. 5, in step S201, the control unit 51 detects the water level of the cooler 33 by the water level sensor S5.

  And it progresses to step S202 and the control part 51 judges whether the electric power generation of the fuel cell 10 needs to be restrict | limited based on the detected water level. When the control unit 51 determines that the generated power limit is not necessary (S202, No), the process returns to step S201. When the control unit 51 determines that the generated power limit is required (S202, Yes), the step S203 is performed. Proceed to

  In step S203, the control unit 51 limits the generated power based on the map shown in FIG. The map shown in FIG. 6 shows the relationship between the water level of the cooler 33 and the generated power limit ratio, and starts limiting the generated power when the water level of the cooler 33 is lower than the predetermined water level L1. Then, as the water level of the cooler 33 is lowered, the limit ratio of the generated power is increased. That is, by suppressing the generated power, the temperature of the fuel cell decreases, the temperature of the cathode offgas decreases, and the humidity of the cathode offgas increases, so that condensation easily occurs, and liquid water (condensed water) is supplied to the cooler 33. Will begin to accumulate. For example, the predetermined water level L1 is set to a water level that can exhibit cooling performance when necessary and does not limit the generated power wastefully.

  Next, control when the operation of the fuel cell device 1A according to the present embodiment is stopped will be described with reference to FIGS. FIG. 7 is a flowchart showing control of the discharge valve based on the temperature of the cooler, and FIG. 8 is a flowchart showing control of the discharge valve based on the timer. Note that the processing in steps S401 and S403 shown in FIG. 8 is the same as steps S301 and S303 shown in FIG.

  As shown in FIG. 7, in step S301, the control unit 51 determines whether or not an ignition off signal (IG-OFF signal), that is, a signal for stopping the operation of the fuel cell device 1A has been acquired, and IG− When the OFF signal is not acquired (No), the process returns to Step S301, and when the IG-OFF signal is acquired (Yes), the process proceeds to Step S302.

  In step S302, the control unit 51 detects the temperature inside the cooler 33 (cooler internal temperature) by the cooler internal temperature sensor S4, and determines whether or not the cooler internal temperature is less than a predetermined temperature. The predetermined temperature is a temperature at which the recovered water (reserved water) in the cooler 33 is determined to be frozen, and is set to 3 ° C., for example.

  In step S302, when the control unit 51 determines that the cooler internal temperature is not lower than the predetermined temperature (No), it repeats the process of step S302 and determines that the cooler internal temperature is lower than the predetermined temperature. If the output value satisfies the predetermined condition (Yes), the process proceeds to step S303.

  In step S303, the control unit 51 opens (opens) the discharge valve 33f. Thereby, the liquid water stored in the cooler 33 is discharged to the outside (outside the vehicle) through the pipe 33e.

  Further, as shown in FIG. 8, in step S402, the control unit 51 starts the operation of the timer 53 at the time of IG-OFF, and determines whether or not a predetermined time has elapsed. The predetermined time can be set according to the temperature by the cooler temperature sensor S4. For example, the lower the temperature by the cooler temperature sensor S4, the shorter the predetermined time.

  In step S402, when it is determined that the predetermined time has not elapsed (No), the control unit 51 repeats the process of step S402, and when it is determined that the predetermined time has elapsed (the output value satisfies the predetermined condition). If yes) (Yes), the discharge valve 33f is opened (opened) (S403). Instead of the cooler temperature sensor S4, determination may be made based on an outside temperature sensor that detects the outside temperature around the fuel cell device 1A.

  As described above, the fuel cell device 1 </ b> A according to the first embodiment converts the fuel cell 10 and the supply gas (air) supplied to the fuel cell 10 from the cathode offgas (offgas) discharged from the fuel cell 10. A humidifier 32 that provides moisture, and is disposed between the fuel cell 10 and the humidifier 32, and includes a water vapor permeable membrane 33j inside, and the cathode off-gas is disposed inside (one surface) of the water vapor permeable membrane 33j, and the outer (other surface). ) And a cooler 33 that lowers the temperature of the cathode offgas by removing heat from the cathode offgas by bringing liquid water (recovered water) into contact with each other. According to this, the temperature of the cathode offgas can be lowered using latent heat (vaporization heat) when the liquid water evaporates, and as a result, the relative humidity of the cathode offgas supplied to the humidifier 32 can be raised. become.

  That is, when the operating temperature of the fuel cell 10 becomes high, the relative humidity of the cathode offgas becomes less than 100%, the water vapor in the pores formed in the hollow fiber membrane evaporates, and the water vapor is transferred in the pores. Damaged. As a result, the humidifier 32 may dry up and may not be able to exhibit sufficient humidification performance. Accordingly, the cooler 33 provided with the water vapor permeable membrane 33j is disposed on the off gas flow path between the fuel cell 10 and the humidifier 32, thereby cooling the cathode off gas and increasing the relative humidity, thereby increasing the humidifier 32. It is possible to prevent the relative humidity of the cathode off gas supplied to 1 from being less than 100%, and to prevent the humidifier 32 from drying up.

  By the way, in the cooler 33 according to the present embodiment, for the cathode offgas having a relative humidity of less than 100%, the moisture passes through the water vapor permeable membrane 33j and comes into contact with the cathode offgas to evaporate, so that the relative humidity increases to 100%. Thus, when the cooling function is exhibited and the relative humidity is already 100%, the water vapor does not pass through the water vapor permeable membrane 33j and contact the cathode offgas to evaporate. ) Does not occur, and the cooling function is not exhibited.

  Since the humidifier 32 can be prevented from drying up in this manner, the humidifier 32 can be operated for a long time. Further, since the humidifier 32 can be prevented from being dried up, the fuel cell is prevented from being insufficiently humidified, and the fuel cell apparatus 1A to 1D can maintain the optimum system humidity and ensure the long-term operation of the fuel cell 10. .

  Further, according to the first embodiment, by adopting the water vapor permeable membrane 33j as the cooler 33, the cooler 33 itself can be made smaller, compared with a cooler having a water-cooled or air-cooled heat exchanger. Thus, the layout can be prevented from being greatly restricted. Further, when the cooler 33 is mounted on a vehicle, it is not necessary to dispose the cooler 33 in a bumper opening or the like, or to add a heat exchanger such as a radiator.

  Further, according to the first embodiment, the recovery unit 35 disposed on the off-gas flow path through which the cathode off-gas flows, and the recovery water introduction for supplying the recovery water recovered by the recovery unit 35 to the cooler 33 as liquid water By providing the pipe b9, the liquid water (condensed water, generated water) discharged from the fuel cell 10 is recovered by the recovery device 35, whereby the cathode offgas is obtained using the liquid water discharged from the fuel cell 10. Can be cooled. As a result, liquid water can be used effectively, and it is not necessary to provide a separate device for supplying liquid water to the cooler 33.

  Further, according to the first embodiment, by providing the cooler 33 in which the hollow fiber-shaped water vapor permeable membrane 33j extends in the vertical vertical direction, liquid water is evenly distributed to the respective hollow fiber water vapor permeable membranes 33j. Can be contacted. Therefore, the heat of the cathode off gas introduced into the cooler 33 is evenly deprived, and the cooling effect can be enhanced.

  Moreover, according to 1st Embodiment, the water level sensor S5 which detects the water level of recovered water, and the discharge valve 33f which discharges | emits recovered water are provided, and the water level of the liquid water in the cooler 33 can be managed. And the cooling function can be maintained properly.

  Further, in the first embodiment, a cooler outlet temperature sensor S2 for detecting the temperature of the cathode off gas derived from the cooler 33 is provided, and as shown in the map of FIG. The allowable temperature value is obtained from the generated power using the relationship with the allowable temperature value of the cathode off-gas at the outlet of 33, and the generated power is limited by comparing the allowable temperature value and the temperature value of the cooler outlet temperature sensor S2 ( Judgment whether to suppress or increase).

  According to this, when the generated power is high and the temperature (actual temperature) of the cooler outlet temperature sensor S2 is higher than the allowable temperature value, the control is performed so as to suppress the generated power. It can be adjusted within the range, and the humidifier 32 can be prevented from drying up. Further, when the generated power is low and the temperature (actual temperature) of the cooler outlet temperature sensor S2 is higher than the allowable temperature value, the low temperature state of the fuel cell 10 is controlled by controlling the generated power to increase. It is relaxed and can suppress flooding and generate a stable cathode off gas with a relative humidity of 100%.

  Moreover, according to 1st Embodiment, since the control part which restrict | limits generated electric power based on the water level of the water level sensor S5 using the relationship between the preset water level of the cooler 33 and generated electric power is provided, the cooler When the water level of 33 is low, the generated power is limited (suppressed) to be easily oversaturated, and liquid water (condensed water) is secured as much as possible to prevent shortage of liquid water. .

  According to the first embodiment, when the operation of the fuel cell device 1A is stopped, the temperature value (output value) of the cooler temperature sensor S4 that detects the temperature of the cooler 33 becomes less than a predetermined temperature. (When a predetermined condition is satisfied), by opening the discharge valve 33f and discharging the liquid water (recovered water) in the cooler 33, the water vapor permeable membrane 33j in the cooler 33 due to freezing of the liquid water Can be prevented from being damaged. Further, according to the first embodiment, when the fuel cell device 1A is started next time, the supply gas (dry gas) supplied to the humidifier 32 is cooled, and the cooled supply gas is supplied to the fuel cell 10, It is possible to prevent the warm-up of the fuel cell 10 from being impaired.

  Further, according to the first embodiment, when the operation of the fuel cell device 1A is stopped, when the time (output value) measured by the timer 53 exceeds a predetermined time (when a predetermined condition is satisfied), By opening the discharge valve 33f and discharging the liquid water (recovered water) in the cooler 33, the water vapor permeable membrane 33j can be prevented from being damaged due to the freezing of the liquid water, and the fuel cell device 1A is started next time. It is possible to prevent the warm-up of the fuel cell 10 from being impaired.

(Modification according to this embodiment)
FIG. 9 is an overall configuration diagram showing a modification of the fuel cell device according to the present embodiment. This fuel cell device 1B is obtained by replacing the collector 35 and the diluter 36 of the fuel cell device 1A according to the first embodiment, and has a configuration in which the collector 35 is arranged on the downstream side of the diluter 36. In addition, the other structure attaches | subjects the same code | symbol and a duplicate description is abbreviate | omitted (same also about other embodiment).

  This fuel cell device 1B causes the gas-liquid separator 21 of the anode system 20 to function as a condensed water recovery device that recovers liquid water (condensed water), and the liquid recovered (stored) by the gas-liquid separator 21. Water is introduced into the diluter 36 through the pipe a5. Thereby, not only the liquid water discharged from the cathode flow path 12 of the fuel cell 10 but also the liquid water discharged from the anode flow path 11 of the fuel cell 10 can be recovered by the recovery device 35, and the fuel cell device 1B The liquid water produced inside can be used more effectively. Moreover, since the gas-liquid separator 21 already provided in the fuel cell device 1B can be used, it is not necessary to provide a separate device. Other effects are the same as those in the first embodiment.

(Other variations according to this embodiment)
FIG. 10 is an overall configuration diagram showing another modification of the fuel cell device according to the present embodiment. This fuel cell device 1 </ b> C has a configuration in which the recovery device 35 is provided on the off-gas flow path between the fuel cell 10 and the cooler 33. In FIG. 10, the recovered water lead-out pipe b10 connected to the cooler 33 is connected so as to merge with the pipe b7 of the off-gas flow path. However, as in the first embodiment and the second embodiment, dilution is performed. It may be connected to the device 36.

  According to this fuel cell device 1C, since the cathode offgas having a high pressure just discharged from the fuel cell 10 is introduced into the recovery device 35, the liquid water (condensed water, recovered water) recovered by the recovery device 35 is cooled. The pump 33 can be easily pumped without using a pump for pumping.

(Still another modification according to this embodiment)
FIG. 11 is an overall configuration diagram showing still another modification of the fuel cell device according to the present embodiment. This fuel cell device 1D has a configuration in which the cooler 33 and the recovery device 35 of the third embodiment are replaced, and the cooler 33 is disposed between the fuel cell 10 and the recovery device 35.

  According to the fuel cell device 1D, the cathode offgas having a relatively high pressure discharged from the cooler 33 is introduced into the recovery device 35, and thus liquid water (condensed water, recovered water) recovered by the recovery device 35 is used. It becomes easy to pump without using the pump for pumping to the cooler 33.

  The present invention is not limited to the above-described embodiments, and in any of the embodiments, the condensate is recovered by the recovery device 35. However, the present invention is not limited to such a configuration, and dilution is performed. Liquid water (condensed water) may be collected in the vessel 36 and supplied from the diluter 36 to the cooler 33 via the collected water introduction pipe b9. Thereby, it is not necessary to newly provide the recovery device 35.

1A, 1B, 1C, 1D Fuel cell device 10 Fuel cell 32 Humidifier (membrane humidifier)
33 Cooler 33j Water vapor permeable membrane 33f Discharge valve 35 Recovery unit (Condensate recovery unit)
51 control unit 53 timer 54 voltage controller b3, b4, b5, b6, b7, b8 piping (off-gas flow path)
b9 Recovered water introduction pipe (recovered water supply flow path)
b10 Recovery water discharge piping S1 Cooler inlet temperature sensor (temperature sensor)
S2 Cooler outlet temperature sensor (temperature sensor)
S3 Refrigerant temperature sensor (temperature sensor)
S4 Cooler temperature sensor (second temperature sensor)
S5 Water level sensor

Claims (7)

A fuel cell;
A membrane humidifier that obtains moisture from off-gas discharged from the fuel cell and supplies moisture to the supply gas supplied to the fuel cell;
It is arranged between the fuel cell and the membrane humidifier, and has a water vapor permeable membrane inside, and the off gas is brought into contact with one of the one surface and the other surface of the water vapor permeable membrane, and liquid water is brought into contact with the other. And a cooler that lowers the temperature of the off gas by removing heat from the off gas. A condensate collector disposed on an off-gas passage through which the off-gas flows;
The fuel cell device according to claim 1, further comprising: a recovered water supply channel that supplies the recovered water recovered by the condensed water recovery device as the liquid water to the cooler.   3. The fuel cell device according to claim 1, wherein the cooler includes a hollow fiber-shaped water vapor permeable membrane extending in a vertical vertical direction. A temperature sensor for determining the temperature of off-gas introduced into the membrane humidifier;
Using the relationship between the power generation power of the fuel cell set in advance and the allowable temperature value of the off-gas introduced into the membrane humidifier, the allowable temperature value is determined from the determined generated power, and the allowable temperature value The fuel cell device according to any one of claims 1 to 3, further comprising a control unit that adjusts the generated power by comparing with a temperature value of the temperature sensor.   5. The fuel cell device according to claim 1, wherein the cooler includes a water level sensor that detects a water level of the recovered water, and a discharge valve that discharges the recovered water. 6.   The fuel cell according to claim 5, further comprising a control unit that limits the generated power based on a water level of the water level sensor using a preset relationship between the water level of the cooler and the generated power. apparatus.   When stopping the operation of the fuel cell device, the second temperature sensor that detects the temperature of the cooler, and at least one output value of a timer that measures the elapsed time from the stop of the operation of the fuel cell device, The fuel cell device according to claim 5, further comprising a control unit that opens the discharge valve when an output value satisfies a predetermined condition.

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