JP4940822B2 - Fuel cell system - Google Patents

Description

  The present invention relates to a fuel cell system, and more particularly to a fuel cell system having a system for collecting water discharged from the fuel cell.

  Conventionally, in a fuel cell using a polymer electrolyte membrane, there are a fuel chamber and an oxygen chamber on both sides of the electrolyte membrane, and the fuel gas in the fuel chamber passes through the fuel electrode or the oxidizing gas (mainly air) in the oxygen chamber. Oxygen inside) is ionized through the oxygen electrode, and the ions are taken out through the electrolyte membrane to obtain electric power. As described above, if ions are taken out through the electrolyte membrane and the electrolyte membrane is dried, the ionic conductivity is lowered, and the energy conversion efficiency is lowered. Therefore, it is necessary to supply moisture to the electrolyte membrane in order to maintain good ion conduction.

By the way, when a fuel cell is constituted by an electrolyte membrane having a thickness equal to or less than a predetermined value, when ions are extracted as described above, water generated by reacting with oxygen in the air at the oxygen electrode is the electrolyte membrane. Reverse osmosis from the oxygen electrode to the fuel electrode. The reversely osmotic water can maintain the electrolyte membrane in a suitable wet state, so that it is not necessary to humidify the fuel gas on the fuel electrode side. However, since the moisture on the oxygen electrode side of the electrolyte membrane evaporates due to the introduced oxidizing gas flow on the oxygen electrode side, the moisture on the oxygen electrode side of the electrolyte membrane is insufficient. Therefore, the oxidizing gas is humidified, and moisture is supplied to the oxygen electrode of the electrolyte membrane with the humidified oxidizing gas.
Thus, when it has the structure which supplies a water | moisture content, the structure which collect | recovers the water produced | generated with the fuel cell and reuses as water for humidification is taken.
JP 2000-12056 A

  However, as shown in Patent Document 1, in the configuration in which the oxidizing gas supply path is open, the oxidizing gas supplied by the heat generation of the fuel cell becomes a high humidity and the supply amount of the oxidizing gas is large. The water generated by the fuel cell cannot be recovered and the water is discharged outside the system. If the operation is continued under such circumstances, it becomes impossible to secure the amount of water necessary for the power generation of the solid polymer fuel cell, and it becomes impossible to construct an ideal fuel cell system that is maintenance-free.

In addition, the conventional water recovery structure uses a plate fin type heat exchanger, but a sufficient water recovery capability cannot be obtained in summer when the temperature is high. Furthermore, if a configuration in which a refrigerator unit is provided in order to increase water recovery efficiency, the energy consumption for driving the refrigerator unit increases, and the energy efficiency of the entire fuel cell system decreases.
An object of the present invention is to provide a fuel cell system that has been made in view of the above-described facts and that is energy efficient and sufficiently capable of recovering moisture.

The present invention for solving the above problems has the following configuration.
(1) A fuel chamber into which fuel gas is introduced and an oxidizing gas chamber having an inlet through which oxidizing gas flows in and an outlet through which oxidized gas after reaction is discharged are disposed adjacent to each other via an electrolyte layer. A fuel cell that generates electricity by reacting with oxidant gas;
A blowing means for sending oxidizing gas to the inlet of the fuel cell;
Cooling means for recovering water by cooling the oxidizing gas discharged from the outlet of the fuel cell;
Cooling control means for adjusting the cooling capacity of the cooling means;
A gas temperature detecting means for measuring the temperature of the oxidizing gas sent to the inlet,
Current detection means for detecting the output current value of the fuel cell;
A flow rate detecting means for detecting the blown amount of the blowing means,
The cooling control means adjusts the cooling capacity of the cooling means based on the gas temperature of the oxidizing gas sent to the inlet, the output current value of the fuel cell, the amount of air blown by the air blowing means and the saturated water vapor curve of the oxidizing gas. The fuel cell system is controlled so that the water content in the system is stored in an appropriate amount .

(2) The cooling control means is based on the sum of the amount of water vapor contained in the oxidizing gas at the inlet and the amount of water produced in the fuel cell among the water vapor contained in the oxidizing gas discharged from the outlet of the fuel cell. Means to determine the dew point; and
The fuel cell system according to (1), further including an adjusting unit that adjusts a cooling capacity of the cooling unit so that a temperature of the oxidizing gas discharged from the cooling unit becomes the dew point.

  (3) The cooling control means has a discharge temperature detection means for measuring the temperature of the oxidizing gas discharged from the cooling means, and the adjustment means has a cooling capacity based on the temperature detected by the discharge temperature detection means. The fuel cell system according to (2), wherein the fuel cell system is adjusted.

  According to the first aspect of the present invention, the amount of water vapor contained in the exhaust gas can be grasped based on the gas temperature of the oxidizing gas sent to the inlet, the output current value of the fuel cell, and the amount of air blown by the air blowing means. Therefore, the amount of water that can be recovered can be adjusted by adjusting the temperature at which the exhaust gas is cooled based on the saturated water vapor curve. As a result, a necessary amount of water can be recovered at all times, and a fuel cell system with high energy efficiency as a whole can be obtained.

According to the second aspect of the present invention, the amount of water in the system is made constant by determining the dew point from the sum of the amount of water vapor contained in the oxidizing gas at the inlet and the amount of generated water generated in the fuel cell. Can be adjusted.
According to the invention described in claim 3, since the temperature of the oxidizing gas finally discharged from the cooling means is detected and the cooling means is adjusted based on the detected value, the amount of water recovered by the cooling means can be more accurately determined. Can be set.

  Next, a preferred embodiment of the present invention will be described. This embodiment is a fuel cell system mounted on an electric vehicle. FIG. 1 is a block diagram showing a configuration of a fuel cell system 1 of the present invention. As shown in FIG. 1, the fuel cell system 1 is roughly configured by a fuel cell stack 100, a fuel supply system 10 including a hydrogen storage tank 11, an air supply system 12, a water supply system 50, and a load system 7. The

  The configuration of the fuel cell stack 100 will be described. The fuel cell stack 100 is configured by connecting fuel cells in series, such as by alternately stacking a plurality of fuel cell unit cells 15 and fuel cell separators 13. 2 is an overall front view showing the fuel cell separator 13, FIG. 3 is a partial cross-sectional plan view of the fuel cell stack 100 composed of the fuel cell separator 13 (AA cross-sectional view in FIG. 2), and FIG. FIG. 5 is a partially enlarged perspective view showing the positional relationship between the current collecting members 3, 4 and the partition wall 7.

  The separator 13 is in contact with the electrode of the unit cell 15 and collects current collecting members 3 and 4 for taking out current to the outside, and frame bodies 8 and 9 that are externally mounted on the peripheral ends of the current collecting members 3 and 4. And a partition wall 7 interposed between the current collecting members 3 and 4. The partition wall 7 prevents direct contact (mixing) of the fuel gas and the oxidizing gas. The current collecting members 3 and 4 and the partition 7 which are current collecting plates are made of metal. The constituent metals of the current collecting members 3 and 4 and the partition walls 7 are metals having electrical conductivity and corrosion resistance, and examples thereof include those obtained by subjecting stainless steel, nickel alloy, titanium alloy or the like to corrosion-resistant conductive treatment. Examples of the corrosion-resistant conductive treatment include gold plating. The current collecting member 3 is in contact with the fuel electrode of the unit cell 15, and the current collecting member 4 is in contact with the oxygen electrode. The current collecting member 3 is formed with a plurality of projecting convex portions 32 by pressing.

  The convex portions 32 are arranged at equal intervals along the long side of the plate material in the short side direction. Hydrogen channels 301 are formed between the convex portions 32 by grooves formed between the convex portions 32 arranged along the long side (lateral direction in FIG. 2), as shown in FIG. As shown, the hydrogen flow path 302 is formed by the groove 33 formed on the back side of the convex portion 32. The surface of the apex portion of the convex portion 32 is a contact portion 321 with which the fuel electrode contacts. Since the current collecting member 3 is a net, the fuel electrode can supply the fuel gas through the hole 320 even in the portion where the contact portion 321 contacts. Further, as shown in FIG. 5, hydrogen gas can also flow between the hydrogen channel 301 and the hydrogen channel 302 via the holes 320. Both ends of the current collecting member 3 extend to a hydrogen supply path (17a or 17b) formed when the separators 13 are stacked.

  The current collecting member 4 has a plurality of convex portions 42 formed by pressing. The convex portions 42 are continuously formed linearly in parallel (vertical direction) to the short sides of the plate material, and are arranged at equal intervals. A groove is formed between the convex portions 42 to form an air flow path 40 through which air flows. The surface of the apex portion of the convex portion 42 is an abutting portion 421 with which the oxygen electrode contacts. Since the current collecting member 4 is a net body, the oxidizing gas (oxygen in the air) can be supplied through the holes 420 even at the portion where the contact portion 421 contacts. The back side of the convex portion 42 is a groove-like hollow portion 41.

  The current collecting members 3 and 4 as described above are overlapped and fixed so that the convex portions 32 and the convex portions 42 are on the outside. At this time, the back side surface 34 of the current collecting member 3 and the back side surface 403 of the air flow path 40 are in contact with the front and back surfaces of the partition wall 7, respectively, and are in a state where they can be energized with each other. As shown in FIG. 3, the air flow path 40 is overlapped with the unit cell 15, and a tubular flow path is formed by closing the groove opening 400, and the inner wall of the air flow path 40 is formed. A part of is composed of an oxygen electrode. Oxygen and water are supplied from the air flow path 40 to the oxygen electrode of the unit cell 15. Further, oxygen and water are supplied from the hollow portion 41 to the oxygen electrode through the mesh of the current collecting member 4. The oxygen supplied to the oxygen electrode is oxygen contained in the air passing through the air flow path 40 and the hollow portion 41.

The opening on one end side of the air flow path 40 is an introduction port 43 through which air and water flow, and the opening at the other end is a discharge port 44 through which air and water flow out. Moreover, the opening part of the one end side of the hollow part 41 becomes the inflow opening port 45 into which air and water flow in, and the opening part of the other end becomes the outflow opening port 46 through which air and water flow out. In the above configuration, the air flow paths 40 and the hollow portions 41 are alternately arranged in parallel and are adjacent to each other with the side wall 47 interposed therebetween. The air flow path 40 from the inlet 43 to the outlet 44, the hollow portion 41 from the inflow opening 45 to the outflow opening 46, and an assembly of these, an oxygen chamber (oxidizing gas) for supplying oxygen to the solid electrolyte membrane Function as a room).
Vent holes 73 are formed at both ends of the partition wall 7, and the long sides of the vent holes 73 are formed to have the same length as the short sides of the current collecting member 3. (17a or 17b) is configured.

  Frame members 8 and 9 are overlaid on the current collecting members 3 and 4, respectively. As shown in FIG. 2, the frame 8 overlaid on the current collecting member 3 is configured to have the same size as the partition wall 7, and a window 81 for accommodating the current collecting member 3 is formed at the center. . Further, in the vicinity of both end portions, a hole 83 is formed at a position that matches the flow hole 73 of the partition wall 7. Between the holes 83 a and 83 b and the window 81, there is a recess for housing the current collecting member 3. The hydrogen flow path 84 is formed. In addition, a concave portion whose contour is formed along the window 81 is formed on the plane opposite to the surface that contacts the current collecting member 3, and a storage portion 82 for storing the unit cell 15 is provided. Yes. The fuel chamber 30 is defined by the surface of the fuel electrode of the unit cell 15 accommodated in the accommodating portion 82, a plurality of alternately arranged hydrogen flow paths 301 and 302, and the window 81. Thus, the fuel chamber is provided adjacent to the fuel electrode, and the oxygen chamber is provided adjacent to the oxygen electrode.

The frame body 9 overlaid on the current collecting member 4 is configured to have the same size as the frame body 8 and the partition wall 7, and a window 91 for accommodating the current collecting member 4 is formed at the center. In addition, holes 93 a and 93 b are formed in the vicinity of both ends at positions corresponding to the flow holes 73 of the partition wall 7.
Grooves 941 and 951 are respectively formed along a pair of opposing long sides of the frame body 9 on the surface of the frame body 9 on which the current collection member 4 is overlapped. The grooves 941 and 951 include the current collection member 4. Upper and lower ends are accommodated. A passage formed by the grooves 941 and 951 and the current collecting member 4 communicates with the oxygen chamber.

  In addition, a concave portion having a contour formed along the window 91 is formed on the plane opposite to the surface of the frame body 9 that contacts the current collecting member 4, and the storage unit in which the unit cell 15 is stored. 92 is provided. A rectangular opening 940 (introduction port covering region (cross section is rectangular)) is formed on the upper surface of the fuel cell stack 100 by the assembly of the openings at the upper end of the current collecting member 4 of the groove 941. Air flows from air manifold 54 to 940.

  FIG. 6 is an enlarged cross-sectional view of the unit cell 15. The unit cell 15 includes a solid polymer electrolyte membrane 15a, and an oxygen electrode 15b and a fuel electrode 15c that are oxidant electrodes stacked on both side surfaces of the solid polymer electrolyte membrane 15a, respectively. The membrane 15a is sandwiched between the oxygen electrode 15b and the fuel electrode 15c. The solid polymer electrolyte membrane 15 a is formed in a size that matches the storage portions 82 and 92, and the oxygen electrode 15 b and the fuel electrode 15 c are formed in a size that matches the windows 91 and 81. Since the thickness of the unit cell 15 is extremely thin compared to the thicknesses of the frame bodies 8 and 9 and the current collecting members 3 and 4, the unit cell 15 is shown as an integral member in the drawing. The inner wall of the air flow path 40 is subjected to hydrophilic treatment. The surface treatment may be performed so that the contact angle between the inner wall surface and water is 40 ° or less, preferably 30 ° or less. As the treatment method, a method of applying a hydrophilic treatment agent to the surface is taken. Examples of the treating agent to be applied include polyacrylamide, polyurethane resin, and titanium oxide (TiO2).

  The separators 13 are configured by holding the current collecting members 3 and 4 by the frames 8 and 9 configured as described above, and the fuel cell stack 100 is configured by alternately stacking the separators 13 and the unit cells 15. . FIG. 7 is a partial plan view of the fuel cell stack 100. A large number of inlets 43 are opened on the upper surface of the fuel cell stack 100. As will be described later, air flows into the inlet 43 from the air manifold 54. The water sprayed from the nozzles 55a and 55b flows in simultaneously. The first and second nozzles 55a and 55b supply water to the fuel cell stack 100 in the form of droplets (mist). The air and liquid water flowing from the inlet 43 cool the current collecting members 3 and 4 by latent heat cooling. Further, on the bottom surface of the fuel cell stack 100, a large number of outlets 44 are opened at positions opposed to the inlets 43 shown in FIG. 7, from which air and water supplied by injection are supplied. leak. That is, many inlets 43 are opened vertically and horizontally on the upper surface of the fuel cell stack 100, and similarly, many outlets 44 are opened vertically and horizontally on the bottom surface of the fuel cell stack 100.

  Next, the configuration of the fuel cell system shown in FIG. 1 will be described. The configuration of the fuel supply system 10 will be described. A hydrogen storage tank 11 that is a fuel gas cylinder is connected to a gas intake port of the fuel cell stack 100 via fuel gas supply channels 201A and 201B. A hydrogen storage tank 11 is connected to one end of the fuel gas supply channel 201A, and a hydrogen source valve 18, a primary pressure sensor S0, a regulator 19, a source electromagnetic valve 20, a pressure sensor S1, a hydrogen pressure regulating valve 21, and a supply electromagnetic valve 22 are provided. One end of the fuel gas supply channel 201B is connected to the other end of the fuel gas supply channel 201A. The other end of the fuel gas supply channel 201B is connected to the IN of the gas inlet 201B of the fuel cell stack 100. In addition to the other end of the fuel gas supply path 201A, one end of a gas discharge path 202 described later is connected to one end of the fuel gas supply path 201B. In the fuel gas supply path 201B, a pressure sensor S2 and a safety valve Vsf are sequentially arranged in the direction of gas fuel gas flow, and one end of an outside air flow path 205 is connected to the upstream side of the safety valve Vsf. . A filter is connected to the other end of the outside air flow path 205, and impurities are filtered from the outside air flowing in by this filter. The outside air flow path 205 is provided with an outside air electromagnetic valve 23.

  The gas discharge port OUT of the fuel cell stack 100 is connected to the other end of a gas discharge channel 202 that is an exhaust circuit. The fuel gas supply channel 201B and the gas discharge channel 202 constitute a circulation path that connects the gas inlet IN and the gas outlet OUT of the fuel cell stack 100. In the gas discharge channel 202, a trap 24, a circulation electromagnetic valve 26, and a circulation pump 25 as a circulation means are arranged in this order from the gas discharge port side of the fuel cell stack 100. A water level sensor S10 is attached to the trap 24, and one end of the gas outlet path 203 is connected to the trap 24. The other end of the gas outlet path 203 is connected to the air duct 124. An exhaust solenoid valve 27 is provided in the gas outlet passage 203.

  Next, the air supply system 12 will be described. The air supply system 12 includes an air introduction path 123, an air manifold 54, and an air duct 124 that is an air discharge path. In the air introduction path 123, a filter 121, an air fan 122, and an air manifold 54 are provided in this order along the inflow direction. From the number of revolutions of the air fan 122, the flow rate q of air (oxidizing gas) flowing into the inlet of the fuel cell stack 100 can be calculated. The air introduction path 123 is provided with a temperature sensor S5 that detects the outside air temperature. From the temperature Tair detected by the temperature sensor S5 and the atmospheric relative humidity Rh, the water amount Wair contained in the outside air can be calculated as will be described later.

On the downstream side of the air introduction path 123, nozzles 55 for injecting cooling water into the openings 940 in the form of mist are provided at positions immediately before the air manifold 54. The nozzle 55 may be provided in the air manifold 54. The air manifold 54 divides and flows the air into the inlet 43 of the fuel cell stack 100.
An exhaust manifold 53A1 is connected to the outlet 44 of the fuel cell stack 100, and the air discharged from the outlet 44 is merged by the exhaust manifold 53A1 and sent to the air duct 124.

  The air duct 124 guides the air flowing out from the outlet 44 to the outside via the condenser 51. At the end of the air duct 124, a condenser 51 to which a cooling device is attached is provided, and then a filter 125 is connected. The condenser 51 extracts moisture from the air. Further, the water evaporated in the fuel cell stack 100 in the water supplied from the nozzle 55 is also collected here. The air duct 124 is provided with an exhaust temperature sensor S9, and the temperature in the fuel cell stack 100 is indirectly detected. A temperature sensor S6 for detecting the exhaust temperature is provided at the exhaust port of the condenser 51. In the condenser 51, a plate fin type heat exchanger and an evaporator that cools using energy at the time of gas compression and expansion are provided in series in the gas flow direction. Is connected to a compressor 512 via a pipe 511 for sending refrigerant. Although not shown, the pipe 511 is provided with a cooling section for cooling the warmed refrigerant between the upstream side of the compressor 512 and the evaporator. The water recovery capability of the condenser 51 can be improved accordingly if the evaporator cooling temperature is lowered, and the evaporator cooling temperature can be controlled indirectly by controlling the rotation of the compressor 512 motor. it can.

  Next, the water supply system will be described. The water supply system 50 includes a water tank 531 as water storage means, a water conduit 57 that guides the water collected by the condenser 51 to the water tank 531, and a water supply passage 56 that guides the water in the water tank 531 to the nozzle 55. A collection pump 62 is provided in the water conduit 57. The recovery pump 62 sends the water extracted from the exhaust gas by the condenser 51 to the water tank 531. The water supply path 56 is provided with a filter 64 and a pump 61 for supplying water to the nozzle 55 as water supply means. The water tank 531 is provided with a water level sensor S5 and a tank water level sensor S7 which is a storage amount detection means.

  A load system 7 is connected to the fuel cell stack 100, and electric power output from the fuel cell stack 100 is supplied to the load system 7. The electrode of the fuel cell stack 100 is connected to an inverter 73 via a wiring 71, and electric power is supplied from the inverter 73 to a load such as a motor. An auxiliary power supply 76 is connected to the inverter 73 via an IGBT (Insulated Gate Bipolar Transistor) 75 which is a switch means. The auxiliary power source 76 can be constituted by, for example, a battery or a capacitor. The load system 7 is provided with a voltage sensor S4 for detecting the output voltage of the fuel cell stack 100 and a current sensor S3 for detecting the output current.

  The control system of the fuel cell system 1 includes a control device ECU as cooling control means. The detected values from the other sensors S0 to S6, S7, S9, and S10 are input to the control device ECU, and the solenoid valves 20, 22, 23, 26, and 27, the other pumps 25 and 62, and the air fan 122 are input. The fan of the condenser 51, the inverter 73, and the IGBT 75 are controlled. The air fan 122 can control the flow rate by controlling the rotation speed, and can calculate the flow rate from the rotation speed. This constitutes a flow rate detection means. Note that an ignition switch (not shown) is connected to this control device, and an instruction signal for driving or stopping a drive motor for driving the vehicle is input.

  In the fuel cell system 1 configured as described above, the water recovery control operation will be described. FIG. 8 is a graph showing a saturated water vapor curve of a gas. The exhaust gas temperature of the fuel cell stack 100 and the temperature at the inlet of the condenser 51 are assumed to be approximately equal and defined as Tin. If the amount of water Wtin relative to the relative humidity at the inlet of the condenser 51 is subtracted by the sum of the generated water Wfc and the amount of outside air brought in by supplying the oxidizing gas (ΔW), it must be recovered downstream of the fuel cell exhaust. In this case, the amount of water supplied in the system will be reduced. On the contrary, the amount of the moisture Wair brought into the outside air from the air supply fan and the amount of water generated in the fuel cell Wfc, which is the amount of water that increases inside the system, may be discarded. Therefore, if the total water amount of the external feeling amount Wair + the fuel cell generation amount Wfc is set as a saturated steam curve dew point, and the temperature of the exhaust gas is controlled and lowered to the dew point by the condenser 51, the condensed water amount ΔW can be obtained. The amount of water in the system is always stored theoretically.

  Control for satisfying the water balance is performed by the control unit ECU so that the control target temperature Td having the dew point of the total moisture content of the outside air brought-in moisture amount Wair and the fuel cell generated water amount Wfc becomes the temperature at the outlet of the condenser 51. , Repeat the compressor ON-OFF and operate the evaporator to control the temperature. Such control contents will be described based on the flowchart shown in FIG.

The output temperature I [A] of the fuel cell stack 100 is acquired from the outside temperature Tair taken in as the oxidant gas taken in by the temperature sensor S5 and the ammeter S3 (step S101). Next, the amount of water brought in outside air Wair and the amount of water generated Wfc in the fuel cell unit are calculated (step S103). The amount of water brought in by the air supply fan
Wair [g / m ³ ] = 5.03exp (0.061 x Tair) x Rh-Formula (1)
It is obtained by. Here, Tair is the outside air temperature [° C.], and Rh is the atmospheric relative humidity measured by a humidity sensor (not shown).
The amount of water generated by fuel cell power generation Wfc is
Wfc [mol / sec] = In / 2F-Formula (2)
Given in. Here, F is the Faraday constant 96500 [c / mol], I is the output current [A] during power generation, and n is the number of stacked layers.

Next, the dew point temperature Td is calculated (step S105). The dew point temperature Td is a control target temperature. For example, it is calculated as follows.
If the molar weight of the formulated water is 18.02 [g / mol] and the flow rate in the fuel cell system is q [m ³ / sec], the formula (2) is
Wfc [g / m ³ ] = 18.02 [g / mol] / (2 × 96500 [c / mol]) × I [c / sec] × n / q [m ³ / sec] Equation (3)
As obtained. Therefore, the total amount WTout of the amount of outside air brought in and the amount of water generated in the fuel cell is
WTout [g / m ³ ] = Wair + Wfc −Formula (4)
As obtained. The temperature at which WTout is the dew point is used, and the target temperature at the evaporator outlet of the heat exchanger is controlled by turning the compressor on and off.

Since the dew point amount WTout is derived from the equations (1)-(3), the control target temperature Td is Td [° C.] = 1 / 0.061 × ln (WTout / 5.03 · RH) = 1 / 0.0.061 × ln ( (Wair + Wfc) /5.03)
-Formula (5)
It is obtained by. Thus, the target temperature Td can be obtained by measuring the temperature Tair of the outside air intake port, the current amount I [A] of the fuel cell, and the flow rate q [m ³ / sec] of the fan in the system.

  Next, the outlet temperature Tout of the condenser 51 is detected by the temperature sensor S6 (step S107).

The compressor 512 is driven (step S109).
Thereafter, Tout and Td are compared to determine whether Td is greater than Tout (step S111). When Td is larger than Tout, it means that water has been sufficiently collected. (FIG. 8 shows a state in which Tout and Td are equal.) In other words, it means that a smaller amount of water than Wair + Wfc is released to the outside, and a water amount greater than the amount of water supplied from the nozzle 55 is recovered. Then, the compressor 512 is turned off (step S113). Next, the amount of water in the water tank 531 is checked (step S115). When the amount of water detected from the water level sensor S7 is an appropriate amount, the process returns to the main routine.

  When the amount of water is not an appropriate amount, the routine proceeds to step 117, where control for changing the contents of compressor control is performed. That is, when the amount of water is excessively larger than the appropriate amount, the target temperature Td is set higher than the value calculated in step S105, the compressor is turned on (step S109), and step S107 is executed. Alternatively, instead of changing the target temperature Td, in step S117, the control content is changed so that the time during which the operation of the compressor 512 is turned on becomes shorter. As a result, the temperature of the exhaust gas increases, and a larger amount of water is discharged outside as water vapor contained in the oxidizing gas.

On the other hand, when the amount of water in the water tank 531 is insufficient, in step S117, the target temperature Td is set lower than the value calculated in step S105, the compressor is turned on (step S109), and step S107 is performed. Execute. Alternatively, instead of changing the target temperature Td, in step S117, the control content is changed so that the time during which the operation of the compressor 512 is turned on becomes longer. As a result, the temperature of the exhaust gas is lowered, a larger amount of water can be recovered from the exhaust gas of the oxidizing gas, and the amount of water in the water tank 531 can be replenished.
By executing the control loop of steps S107, S109, S111, S113, S115, S117, and S109 as described above, the amount of water in the water tank is controlled.

When the amount of water in the water tank 531 is excessive, the outside air temperature detected by the outside air temperature sensor is low, and the water tank 531 is provided with the water tank 531 only when the water vapor contained in the oxidizing gas cannot be sufficiently discharged. You may open the drain valve and drain the water. This is an effective means in terms of intentionally improving the water quality in the system.
In step S111, when Tout is larger than Td, step S117 is executed and control is performed so that Tout decreases.
As described above, the amount of water can be adjusted by changing the control target temperature around the dew point obtained by Wair + Wfc, and an excessively large cooling device is not required. Will also improve.

1 is a block diagram showing a fuel cell system 1 of the present invention. It is a whole front view which shows the separator for fuel cells. It is a fragmentary sectional top view (AA sectional view) of the fuel cell stack comprised with the fuel cell separator. It is the whole fuel cell separator rear view. It is a partial expansion perspective view which shows the positional relationship of a current collection member and a partition. It is an expanded side sectional view which shows the structure of a unit cell. It is a fragmentary top view which shows the structure of the upper surface of a fuel cell stack. It is a graph which shows a saturated water vapor curve. It is an operation | movement flowchart of water collection | recovery control.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell system 100 Fuel cell stack 123 Air introduction path 51 Condenser 531 Water tank 53A1 Exhaust manifold 54 Air manifold 55 Nozzle 61 Supply pump 512 Compressor

Claims (3)

A fuel chamber into which the fuel gas is introduced and an oxidizing gas chamber having an inlet through which the oxidizing gas is introduced and an outlet through which the oxidized gas after the reaction is discharged are adjacent to each other via the electrolyte layer, and the fuel gas and the oxidizing gas A fuel cell that generates electricity by reacting with
A blowing means for sending oxidizing gas to the inlet of the fuel cell;
Cooling means for recovering water by cooling the oxidizing gas discharged from the outlet of the fuel cell;
Cooling control means for adjusting the cooling capacity of the cooling means;
A gas temperature detecting means for measuring the temperature of the oxidizing gas sent to the inlet,
Current detection means for detecting the output current value of the fuel cell;
A flow rate detecting means for detecting the blown amount of the blowing means,
The cooling control means adjusts the cooling capacity of the cooling means on the basis of the gas temperature of the oxidizing gas sent to the inlet, the output current value of the fuel cell, the blowing amount of the blowing means, and the saturated water vapor curve of the oxidizing gas. And controlling the water content in the system so as to store it in an appropriate amount . The cooling control means calculates a dew point from the sum of the amount of water vapor contained in the oxidizing gas at the inlet and the amount of water produced in the fuel cell among the water vapor contained in the oxidizing gas discharged from the outlet of the fuel cell. Means to determine,
The fuel cell system according to claim 1, further comprising an adjusting unit that adjusts a cooling capacity of the cooling unit such that a temperature of the oxidizing gas discharged from the cooling unit becomes the dew point. The cooling control means has discharge temperature detection means for measuring the temperature of the oxidizing gas discharged from the cooling means, and the adjustment means adjusts the cooling capacity based on the temperature detected by the discharge temperature detection means. The fuel cell system according to claim 2.

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