JP2005158430A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system suitable to perform sufficient water elimination. <P>SOLUTION: A reactive gas passage 6 for supplying a reactive gas to the gas diffusion electrode of a fuel cell is formed on a surface side of a separator 4. The system comprises a reactive gas supplying means 2 for distributing the reactive gas to the passage 6. An area of the separator 4 facing at least the downstream side of the reactive gas passage 6 is formed of a porous body. The system further comprises a recovered gas passage 7 formed so as to distribute recovered gas to the reverse side of the separator 4 in at least the downstream area of the reactive gas passage 6, and a recovered gas supplying means 3 for distributing the recovered gas to the recovered gas passage 7. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fuel cell system, and more particularly, to a fuel cell system suitable for conditioning a reaction gas.

In order to prevent the “flooding phenomenon” in which water generated by the battery reaction has blocked the gas diffusion layer and gas flow path, the separator that forms the reaction gas flow path is formed of a porous body and generated using the capillary phenomenon. A fuel cell that moves water from a naturally wet to a dry one has been proposed (see Patent Document 1).
JP-A-8-138691

  However, in the above-mentioned conventional example, water is moved and uniformized in the porous due to the capillary phenomenon, so that sufficient removal is required when the water generation rate is faster than the water moving rate in the porous. There was a problem that water was not used.

  Accordingly, the present invention has been made in view of the above problems, and an object thereof is to provide a fuel cell system suitable for performing sufficient water removal.

  The present invention comprises a reaction gas flow path for supplying a reaction gas to a gas diffusion electrode of a fuel cell on the surface side of the separator, and a reaction gas supply means for circulating the reaction gas in the reaction gas flow path. A region that faces at least the downstream side of the channel is formed of a porous body, and a recovery gas channel that is formed so as to distribute the recovery gas to the back side of the separator in at least the downstream region of the reaction gas channel, and the recovery gas in the recovery gas channel And a recovered gas supply means for circulating the gas.

  Therefore, the present invention comprises a reaction gas channel for supplying a reaction gas to the gas diffusion electrode of the fuel cell on the surface side of the separator, and a reaction gas supply means for circulating the reaction gas in the reaction gas channel. A recovery gas channel formed so that a region facing at least the downstream side of the gas channel is formed of a porous body, and a recovery gas is circulated to the back side of the separator in at least the downstream region of the reaction gas channel, and a recovery gas channel Since the recovery gas supply means for circulating the recovery gas is provided, the water condensed in the reaction gas channel and absorbed in the porous body of the separator evaporates into the recovery gas on the back side. Can be removed. In addition, since the downstream area of the reaction gas channel is cooled by the latent heat of vaporization when the water absorbed by the porous body evaporates into the recovered gas, the amount of water contained in the exhaust gas that has passed through the reaction gas channel is reduced. It is not necessary to recover water from the exhaust gas via a condenser or the like.

  Hereinafter, the fuel cell system of the present invention will be described based on each embodiment.

(First embodiment)
FIG. 1 is a schematic configuration diagram showing a fuel cell system according to a first embodiment to which the present invention is applied, and a separator for supplying a reaction gas (air) to a cathode side gas diffusion electrode laminated on one side of a solid polymer membrane. The reaction gas supply system containing is shown.

  In FIG. 1, a fuel cell system 1 includes a reaction gas supply system 2 (reaction) provided with a reaction gas channel 6 for supplying a reaction gas to a cathode side gas diffusion electrode laminated on one side of a polymer membrane on the surface side of a separator 4. Gas supply means) and a water recovery gas system 3 (recovered gas supply means) provided with a recovery gas flow path 7 partially along the reaction gas flow path 6 of the reaction gas supply system 2 on the back side of the separator 4. .

  The reaction gas supply system 2 is supplied from a blower 10 or a compressor to a reaction gas channel 6 provided on the surface side of the separator 4, that is, on the surface side in contact with the cathode side gas diffusion electrode laminated on one side of the polymer film. The reaction gas is supplied via the inlet manifold 12 and discharged from the reaction gas flow path 6 via the reaction gas outlet manifold 14 and the reaction gas pressure adjusting valve 16. The flow rate of the reaction gas flowing through the reaction gas channel 6 is adjusted by the supply flow rate of the blower 10, and the pressure of the reaction gas is adjusted by the reaction gas pressure adjustment valve 16.

  The separator 4 includes a frame-shaped portion 4 </ b> A having manifolds, and a gas flow path portion 4 </ b> B that is in contact with the gas diffusion electrode and has a reaction gas flow path 6. In the illustrated example, the reaction gas flows into the reaction gas channel 6 from the inlet manifold 12 provided at the lower left corner of the separator 4 and flows from the upstream side to the downstream side along the bent reaction gas channel 6. The reaction gas that diffuses into the diffusion electrode and is consumed in the power generation reaction and reaches the downstream side is discharged from an outlet manifold 14 provided at the upper right corner of the separator 4.

  The water recovery gas system 3 includes a back side gas passage 7 (see the broken line illustration) provided on the back side of the separator 4, that is, the back side of the surface in contact with the gas diffusion electrode, and the back side gas passage 7. A blower 20 or a compressor for supplying the recovered gas via the backside gas inlet manifold 18 and a backside gas pressure adjusting valve 24 for discharging the gas from the backside gas flow path 7 via the backside outlet manifold 22 are provided. The flow rate of the gas in the back side gas flow path 7 is adjusted by the supply flow rate of the blower 20, and the pressure of the back side gas is adjusted by the back side gas pressure adjustment valve 24. The back side gas inlet manifold 18 and the outlet manifold 22 are arranged in a frame-like portion of the separator 4, and the back side gas flow path 7 is arranged on the back side of the separator 4 in a region where the downstream side of the reaction gas flow path 6 exists.

  The separator 4 is formed into a porous porous body in a region where at least the back side gas flow path 7 and the reaction gas flow path 6 of the gas flow path portion 4B are adjacent to each other with the separator 4 interposed therebetween. In the road region, it is formed in either a porous body or a dense body. For this reason, when water exists in the reaction gas flow path 6 on the downstream side, the water is absorbed and removed by the separator 4 which is a porous body.

  The operation of the fuel cell system configured as described above will be described below.

  During operation of the fuel cell system 1, in the reaction gas supply system 2, the reaction gas pressure is adjusted by the blower 10 through the inlet manifold 12 of the separator 4 to the reaction gas flow path 6 and through the outlet manifold 14. In the water recovery gas system 3, the gas is discharged from the valve 16, supplied to the backside gas passage 7 via the backside gas inlet manifold 18 of the separator 4 by the blower 20, and backside gas pressure adjusting valve 24 via the outlet manifold 22. Discharged from.

  The reaction gas supplied to the reaction gas channel 6 is diffused to the gas diffusion electrode while flowing toward the downstream side along the reaction gas channel 6 to be used for the power generation reaction. The water generated by the power generation reaction is converted into water vapor by reaction heat and mixed with the reaction gas, and flows through the reaction gas flow path 6 together with the reaction gas. The amount of water vapor contained in the reaction gas increases as it goes downstream of the reaction gas channel 6, and the reaction gas temperature also rises as it goes downstream, so that the amount of saturated water vapor also increases.

  If the amount of water vapor contained in the reaction gas exceeds the amount of saturated water vapor corresponding to the temperature rise of the reaction gas at that time point, water droplets are condensed on the wall surface of the reaction gas passage 6 on the downstream side of the reaction gas passage 6. . The condensed water droplets are absorbed by the porous body of the separator 4 and removed. The water absorbed by the porous body is evaporated to the recovered gas flowing through the backside gas passage 7 and is transported by the recovered gas, so that water droplets continuously condensed on the reaction gas channel 6 side are absorbed and removed. Can be watered.

  In addition, since the porous body is cooled by the heat of vaporization when the water absorbed and removed by the porous body is evaporated to the recovered gas, the temperature of the reaction gas on the downstream side of the reaction gas flow path 6 is lowered, and the reaction The saturated water vapor amount of the gas decreases, condenses as water droplets, is similarly absorbed and dehydrated by the porous body, and is recovered by the recovered gas as described above. For this reason, the amount of water vapor contained in the reaction gas discharged to the outlet manifold 14 can be reduced. That is, water necessary for humidifying the reaction gas can be recovered by the porous body and the recovery gas, and water taken out by the reaction gas can be reduced.

  FIG. 2 is a graph showing a change in gas temperature in the reaction gas channel 6 between this embodiment and a so-called “co-flow type” comparative example in which the flow direction of the cooling water is formed along the reaction gas channel. is there. In FIG. 2, in the comparative example shown by the broken line, the temperature rises simply as the reaction gas flow path proceeds from the inlet to the outlet, and reaches the highest temperature near the outlet. For this reason, in the comparative example, flooding in the downstream region of the reaction gas channel 6 can be suppressed to some extent, but a large amount of water (water vapor) is taken out of the fuel cell, and the water is used as the reaction gas. In order to use this for humidification, it is necessary to provide a condenser for condensing water by cooling the reaction gas at a high temperature.

  On the other hand, in the present embodiment, as shown by the solid line in FIG. 2, the temperature of the reaction gas rises up to the middle of the reaction gas flow path 6, but the porous body has the back gas flow path 7 disposed on the back side. When the reaction gas flow path 6 is reached, the porous body is cooled by the latent heat of vaporization when the water inside the porous body evaporates to the backside gas flow path 7, so that the reaction gas temperature is lowered and the water (water vapor) fuel cell It is possible to reduce taking out to the outside.

  In the above embodiment, the recovery gas inlet manifold 18 is provided so as to be adjacent to the outlet manifold 14 of the reaction gas flow path 6. It is good also as a structure arrange | positioned adjacent to the exit manifold of a reactive gas.

  In the present embodiment, the following effects can be achieved.

  (A) A reaction gas flow path 6 for supplying a reaction gas to the gas diffusion electrode of the fuel cell is formed on the surface side of the separator 4, and a reaction gas supply means 2 for flowing the reaction gas through the reaction gas flow path 6 is provided. A recovery gas channel formed so that a region facing at least the downstream side of the four reaction gas channels 6 is formed of a porous body and the recovery gas is circulated on the back side of the separator 4 in at least the downstream region of the reaction gas channel 6. 7 and the recovery gas supply means 3 for circulating the recovery gas in the recovery gas flow path 7, the water condensed in the reaction gas flow path 6 and absorbed in the porous body of the separator 4 is contained in the recovery gas on the back side. Since it evaporates, liquid water can be removed from the reaction gas channel 6. Further, since the downstream area of the reaction gas channel 6 is cooled by the latent heat of vaporization when the water absorbed by the porous body evaporates in the recovered gas, the amount of water contained in the exhaust gas that has passed through the reaction gas channel 6 It is not necessary to recover water from the exhaust gas via a condenser or the like.

(Second Embodiment)
3 to 9 show a second embodiment of a fuel cell system to which the present invention is applied, FIG. 3 is a system configuration diagram of a fuel cell system of a first example of the second embodiment, and FIG. 4 is a second embodiment. 5 is a system configuration diagram of a fuel cell system according to a second example of the embodiment, FIG. 5 is a system configuration diagram of a fuel cell system according to a third example of the second embodiment, and FIGS. 6 to 8 are fourth examples of the second embodiment. FIG. 9 is a system configuration diagram of a fuel cell system according to a fifth example of the second embodiment. In the present embodiment, a reactive gas is supplied as a recovered gas, and the reactive gas as a humidified recovered gas is caused to flow into the reactive gas flow path. The same devices as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted or simplified.

  In the first example of the second embodiment shown in FIG. 3, the downstream pipe 26 of the back side gas pressure regulating valve 24 of the water recovery gas system 3 is connected to the upstream side of the blower 10 of the reaction gas supply system 2 to recover the water. The reaction gas is supplied to the gas system 3. Other configurations are the same as in the first embodiment.

  In this first embodiment, the reaction gas discharged from the back side gas pressure adjustment valve 24 of the water recovery gas system 3 is mixed with the reaction gas newly supplied to the reaction gas supply system 2 and sucked by the blower 10 to react. The gas is supplied to the gas supply system 2. The reaction gas refluxed from the water recovery gas system 3 contains water condensed on the downstream side of the reaction gas channel 6 as water vapor, and reacts by mixing with the newly supplied reaction gas. The gas is humidified, and the humidified reaction gas can be supplied to the reaction gas channel 6.

  In the above-described embodiment, the case where the water recovery reaction gas and the newly supplied reaction gas are merged and supplied to the reaction gas supply system 2 has been described. The entire amount of the recovered reaction gas may be supplied to the reaction gas supply system 2 as it is.

  In the fuel cell system 1 of the second example of the second embodiment shown in FIG. 4, the water recovery reaction gas is mixed with the reaction gas of the reaction gas supply system 2 by the ejector 28 provided downstream of the blower 10. It is. By mixing using the ejector effect of the ejector 28, a compressor and a blower are unnecessary, the back side gas pressure adjustment valve 24 is omitted, and a flow rate for adjusting the flow rate of the water recovery reaction gas supplied to the back side gas flow path 7. A regulating valve 30 is disposed upstream of the backside gas inlet manifold 18. Other configurations are the same as those in the first embodiment.

  In this embodiment, the suction is performed by the ejector 28 and the flow rate is adjusted by the flow rate adjusting valve 30 on the inlet side. Therefore, the pressure of the water recovery reaction gas in the back side gas flow path 7 becomes negative, and positively Water evaporation from the porous body can be promoted, and the reaction gas in the reaction gas supply system 2 can be humidified.

  In the fuel cell system 1 of the third example of the second embodiment shown in FIG. 5, the mixing ratio of the water recovery reaction gas supplied to the reaction gas supply system 2 and the newly supplied reaction gas can be adjusted. is there. For this reason, the flow rate adjusting valves 32 and 34 are respectively arranged at the joining portion of the water recovery reaction gas and the new reaction gas, and the blower 10 of the reaction gas supply means 2 is arranged downstream thereof. Other configurations are the same as those of the second embodiment.

  In this embodiment, the ratio of the reaction gas discharged from the blower 10 to the suction reaction gas supply system 2 can be adjusted by adjusting the opening degree of each flow rate adjustment valve 32, 34. The recovered reaction gas can be supplied to the backside gas flow path 7. Also in this embodiment, the pressure of the water recovery reaction gas in the backside gas passage 7 is in a negative pressure state, and water evaporation from the porous body can be actively promoted, and the reaction gas in the reaction gas supply system 2 is humidified. can do.

  The fuel cell system 1 of the fourth example of the second embodiment shown in FIG. 6 is configured to increase the backside gas flow rate according to the load of the fuel cell. That is, the configuration of the reaction gas supply means 2 and the recovered gas supply means 3 is the same as that of the first embodiment shown in FIG. 3, and the supply flow rates of the blowers 10 and 20 and the gas pressure adjustment valves 14 and 24 of both systems are The pressure adjustment value is adjusted by the controller 9 in accordance with the input load of the fuel cell.

  FIG. 7 is a graph showing the control characteristic of the backside gas flow rate with respect to the load of the fuel cell, which is executed by the controller 9, and the backside gas supply means 3 increases the backside gas flow rate as the load of the fuel cell increases. The number of rotations of the blower 20 is increased. In reality, the setting of the backside gas flow rate is not simply determined only by the fuel cell load, but the temperature of the reaction gas, the temperature of the backside gas, the amount of generated water (power generation amount), the gas pressure, etc. are considered. The flow value obtained in this way is set as the target value for the backside gas flow rate.

  In this way, by increasing the backside gas flow rate according to the load of the fuel cell, even when the amount of condensed water generated on the downstream side of the reaction gas flow path 6 becomes large as the load increases, the total amount thereof The amount of water vapor evaporated in the backside gas passage 7 can be increased according to the backside gas flow rate so that the porous body absorbs and removes water.

  That is, since a large amount of generated water is generated when the fuel cell load is large, in order to remove more water from the reaction gas flow path 6, the flow rate of the backside gas is increased to promote evaporation. Conversely, since flooding is unlikely to occur when the load is small, the flow rate of the backside gas is reduced, and the amount of energy consumed by the backside gas supply compressor 20 is reduced. Further, since the amount of generated water is small when the load is small, the back side gas flow rate is reduced to prevent the porous body of the separator 4 from being dried out. Accordingly, it is possible to efficiently cope with a change in the amount of generated water in the stack due to an increase or decrease in the fuel cell load.

  FIG. 8 is another control mode executed by the controller 9, and is a graph showing a differential pressure characteristic between the pressure of the reaction gas and the pressure of the backside gas with respect to the load of the fuel cell, and as the load of the fuel cell increases. Thus, the opening degree of each pressure adjusting valve 16, 24 is adjusted so that the differential pressure between the reaction gas pressure and the backside gas pressure becomes large. Specifically, the opening degree of the back side gas pressure adjustment valve 24 for adjusting the back side gas pressure is set larger than the opening degree of the reaction gas pressure adjustment valve 16 so that the reaction gas pressure becomes higher than the back side gas pressure. The pressure difference is set so as to increase according to the load.

  By setting in this way, the driving force in which the water condensed in the reaction gas channel 6 moves inside the porous body is increased, and a larger amount of water can be removed from the reaction gas channel 6. That is, since a large amount of water is generated when the load is large, it is possible to move more water into the porous portion by increasing the pressure difference between the reaction gas flow path 6 and the back side gas flow path 7. Since the amount of generated water is small when the load is small, the pressure difference can be reduced and the front side gas can be prevented from escaping to the back side. Therefore, it is possible to efficiently cope with a change in the amount of generated water in the stack due to an increase or decrease in load.

  In the fuel cell system 1 of the fifth example of the second embodiment shown in FIG. 9, a liquid water separator 36 is disposed at the outlet of the back side gas flow path 7. That is, when the amount of water produced by the fuel cell is larger than the amount of water necessary for humidifying the reaction gas, the liquid water is separated and removed by the liquid water separator 36.

  For example, when the humidity of the outside air is high, or when the operating temperature of the fuel cell is low immediately after startup, a situation occurs in which the amount of water generated by the fuel cell is greater than the amount of water required for gas humidification. In such a case, by operating the liquid water separator 36, the reaction gas flow path 6 is closed by the liquid water component (mist) in the reaction gas when the backside gas is merged with the reaction gas, and the gas diffusion of the reaction gas. It is possible to prevent the diffusion to the layer from being deteriorated. Further, the liquid water separator 36 separates liquid water that is not evaporated to the back side gas flow path 7 in the stack and is discharged as liquid water when the amount of generated water is large due to high load operation. It can be removed.

  In the present embodiment, in addition to the effect (a) in the first embodiment, the following effects can be achieved.

  (A) A reaction gas channel 6 for supplying a reaction gas to the gas diffusion electrode of the fuel cell is formed on the surface side of the separator 4, and a reaction gas supply means 2 for circulating the reaction gas through the reaction gas channel 6 is provided. A recovery gas channel formed so that a region facing at least the downstream side of the four reaction gas channels 6 is formed of a porous body and the recovery gas is circulated on the back side of the separator 4 in at least the downstream region of the reaction gas channel 6. 7 and a recovery gas supply means 3 for circulating the recovery gas in the recovery gas flow path 7, the recovery gas supply means 3 supplies a reaction gas to the recovery gas flow path 7, and a recovery gas flow In order to make the reaction gas passing through the passage 7 part or all of the reaction gas supplied to the reaction gas channel 6 by the reaction gas supply means 2, the reaction gas humidified in the recovery gas channel 7 on the back side is used as the reaction gas. Flow path Can be supplied, it is possible to supply the humidified reaction gas into the reaction gas channel 6.

  (C) As in the fourth embodiment, when the flow rate of the recovery gas flowing through the recovery gas passage 7 is controlled to increase or decrease by the recovery gas supply means 3 in accordance with the load of the fuel cell, Efficiently respond to changes in the amount of water produced.

  (D) In FIG. 8 of the fourth embodiment, since the pressure of the recovered gas flowing through the recovered gas passage 7 is controlled to increase / decrease by the recovered gas supply means 3 according to the load of the fuel cell, It is possible to efficiently cope with the increase / decrease in the amount of generated water in the stack, and when the load with a small amount of generated water is small, the pressure difference can be reduced to prevent the front side gas from escaping to the back side.

  (E) In the fifth embodiment, the recovered gas supply means 3 includes a separator 36 for removing liquid water at the outlet of the recovered gas flow path 7, so that the amount of generated water is large for high load operation, and the back side in the stack Liquid water that does not evaporate into the gas flow path 7 and comes out as liquid water can be removed by the liquid water separator 36.

(Third embodiment)
FIG. 10 is a system configuration diagram showing a third embodiment of the fuel cell system to which the present invention is applied. In the present embodiment, a portion other than the region constituted by the porous body of the separator is formed into a water-impermeable dense material, and a cooling water passage for circulating cooling water is provided on the back side of the reaction gas passage. Is. In addition, the same code | symbol is attached | subjected to the same apparatus as 1st, 2 embodiment, and the description is abbreviate | omitted or simplified.

  In FIG. 10, the separator 4 faces the downstream side of the reaction gas flow path 6 and is formed as a porous region, and the separator 4 faces the upper middle stream side of the reaction gas flow path 6 and has a water impermeable denseness. And formed region B. A cooling water passage 41 (see the broken line illustration) is formed on the back surface side of the region B formed in a water impermeable and dense area, and the cooling water inlet manifold 42 and the cooling water outlet manifold of the cooling water passage 41 are formed in the frame-like portion 4A. 44 is formed. The cooling water is supplied from the cooling water tank 46 to the cooling water inlet manifold 42 by the pump 48 and is circulated and supplied by the cooling water circulation system 40 that returns from the cooling water outlet manifold 44 to the cooling water tank 46. Other configurations are the same as those of the second embodiment.

  Thus, by providing the dense region B of the separator 4 and forming the cooling water channel 41 on the back surface side of the reaction gas channel 6, cooling with a new cooling water channel for flowing cooling water is performed. There is no need to provide a plate, the back side gas passage 7 and the cooling water passage 41 can be formed on the same plane, the cell pitch of the fuel cell stack can be reduced, the degree of stacking can be increased, and the number of parts can also be increased. Can be reduced. In addition, the porous body A part in which the cooling water flow path 41 of the separator 4 is not disposed is cooled by the latent heat of vaporization as described above, and does not need to be cooled by the cooling water.

  As shown in FIG. 10, when the upstream portion of the cooling water flow channel 41 near the inlet manifold 42 is provided adjacent to the upstream portion of the reaction gas flow channel 6, the inlet (upstream portion) of the reaction gas flow channel 6 is provided. ) The temperature in the vicinity can be lowered, and as shown in FIG. 11, even if the amount of water is the same, the amount of saturated water vapor is decreased by the amount of the temperature decrease, the relative humidity is increased, and the drying of the polymer film can be prevented. it can. Therefore, the upstream part of the reaction gas channel 6 can be made the lowest temperature, and the polymer film can be prevented from being dried out due to a decrease in humidity near the inlet of the reaction gas channel 6.

  Further, as shown in FIG. 10, the cooling water channel 41 is configured to flow from upstream to downstream in parallel with the reaction gas channel 6 on the front and back of the separator 4. With this configuration, the reaction gas temperature rises as it goes downstream. As a result, the saturated vapor pressure rises as the reaction gas proceeds downstream, and the generated water evaporates into the gas, so that flooding in the dense region B can be prevented.

  In the present embodiment, in addition to the effects (a) in the first embodiment and the effects (a) to (d) in the second embodiment, the following effects can be achieved.

  (F) The separator 4 is formed in a water-impermeable dense structure excluding a region facing at least the downstream side of the reaction gas flow path 6, and is formed on the back side of the separator 4 on which the upper middle flow portion of the reaction gas flow path 6 is formed. In order to form the cooling water flow path 41 through which the cooling water flows and to allow the cooling water to flow through the cooling water flow path 41 by the cooling water supply means 40, the backside recovery gas flow path 7 and the cooling water flow path 41 are formed on the same plane. As a result, the cell pitch can be reduced. In addition, since the porous part is cooled by the evaporation latent heat of water, there is no need for cooling with cooling water.

  (G) Since the upstream part of the cooling water channel 41 is arranged adjacent to the upstream side of the reaction gas channel 6 from the back side of the separator 4, the upstream part of the reaction gas channel 6 can be at the lowest temperature, Drying out of the polymer film due to a decrease in humidity near the inlet can be prevented.

  (H) Since the cooling water channel 41 is arranged adjacent to the reaction gas channel 6 on the front and back of the separator 4 so as to flow in the same direction from upstream to downstream, the reaction gas temperature is increased from the upstream. It can be raised as it goes downstream, and flooding can be suppressed.

  In the above embodiment, the separator 4 having the reaction gas flow path 6 for supplying air to the gas diffusion electrode is assumed as the target separator 4. The present invention may be applied to a separator that includes a reaction gas flow path for supplying a gas.

1 is a schematic configuration diagram of a fuel cell system showing an embodiment of the present invention. The graph which shows the reaction gas temperature distribution of this embodiment and a comparative example. The schematic block diagram of the fuel cell system which shows the 1st Example of 2nd Embodiment of this invention. The schematic block diagram of the fuel cell system which shows the 2nd Example of 2nd Embodiment of this invention. The schematic block diagram of the fuel cell system which shows the 3rd Example of 2nd Embodiment of this invention. The schematic block diagram of the fuel cell system which shows the 4th Example of 2nd Embodiment of this invention. The characteristic view which similarly shows the control characteristic of 4th Example. The characteristic view which shows another control characteristic of 4th Example similarly to (A) and (B). The schematic block diagram of the fuel cell system which shows 5th Example of 2nd Embodiment of this invention. The schematic block diagram of the fuel cell system which shows 3rd Embodiment of this invention. The graph which shows the humidity distribution of the reaction gas of this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell system 2 Reaction gas supply system, reaction gas supply means 3 Collection | recovery gas supply system, collection | recovery gas supply means 4 Separator 6 Reaction gas flow path 7 Recovery gas flow path, back side gas flow path 9 Controller 10, 20 Blower, compressor 12 Reaction gas inlet manifold 14 Reaction gas outlet manifold 16, 24 Pressure adjustment valve 18 Recovery gas inlet manifold, backside gas inlet manifold 22 Recovery gas outlet manifold, backside gas outlet manifold 28 Ejector 30, 32, 34 Flow rate adjustment valve 36 Liquid water separator 40 Cooling water supply means 41 Cooling water flow path 42 Cooling water inlet manifold 44 Cooling water outlet manifold 46 Cooling water tank 48 Pump

Claims (8)

In the fuel cell system comprising a reaction gas flow path for supplying a reaction gas to the gas diffusion electrode of the fuel cell on the surface side of the separator, and a reaction gas supply means for flowing the reaction gas through the reaction gas flow path,
A region facing at least the downstream side of the reaction gas flow path of the separator is formed of a porous body,
A recovery gas channel formed to circulate the recovery gas on the separator back side of at least the downstream region of the reaction gas channel;
And a recovery gas supply means for circulating the recovery gas in the recovery gas flow path.   The recovery gas supply means supplies a reaction gas to the recovery gas flow path, and the reaction gas passing through the recovery gas flow path is part or all of the reaction gas supplied to the reaction gas flow path by the reaction gas supply means. The fuel cell system according to claim 1.   3. The fuel cell system according to claim 1, wherein the flow rate of the recovery gas flowing through the recovery gas passage is controlled to increase or decrease by a recovery gas supply unit according to a load of the fuel cell.   3. The fuel cell system according to claim 1, wherein the pressure of the recovery gas flowing through the recovery gas passage is controlled to increase or decrease by a recovery gas supply unit according to a load of the fuel cell.   The fuel cell system according to any one of claims 1 to 4, wherein the recovery gas supply means includes a separator that removes liquid water at an outlet of the recovery gas flow path. The separator is formed in a dense water-impermeable manner excluding a region facing at least the downstream side of the reaction gas flow path, and cooling water is circulated on the back side of the separator where the upper middle flow portion is formed. Forming a water channel,
The fuel cell system according to any one of claims 1 to 5, wherein the fuel cell system includes a cooling water supply means for circulating cooling water through the cooling water flow path.   The fuel cell system according to claim 6, wherein the upstream portion of the cooling water channel is disposed adjacent to the upstream side of the reaction gas channel from the back side of the separator.   8. The fuel cell system according to claim 6, wherein the cooling water flow path is disposed adjacent to the reaction gas flow path on the front and back sides of the separator so as to flow in the same direction from upstream to downstream. .

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